# Late Season / Winter Solar Kilns



## Coalescent (Sep 10, 2019)

Thanks to the great information provided here and on other firewood forums, I made an attempt at my own solar kilns based off @Woodsplitter67's excellent, @Poindexter-approved design. I will be running at least one into the winter.

*Background*

Last October I moved from my home in the Monadnock region of NH to north of Mount Kearsarge onto an 18 acre piece of land with about 16 acres very heavily wooded. Mostly 90' pine trees with a few hardwoods here and there. I left my 9 cords of hardwood cut and stacked with my old home as part of the sale, so I am starting fresh.

*Solar Kilns*

I have access to free pallets so I based my design off using those pallets and trying to adhere as closely as possible to @Woodsplitter67's design.

Each kiln holds 2.20 cords of wood, with 1.10 cords in each row.

I completed and fully wrapped my first kiln on August 7th. I completed and fully wrapped my second kiln on September 6th. The first kiln is behind the newer kiln. If my math is correct, I spaced the kilns far enough apart that the shadow of the second kiln shouldn't land on the first kiln even in winter.







*State of Wood*

My wood is not ideal. I hope to have a better baseline next year, but this year I am just trying to get everything in shape to survive the coming winter and have some decent wood to burn. All of my splits are 16" splits. Thickness varies.

First Kiln​
In my first kiln I have half hardwood (mostly red oak and birch, a little beech) and half softwood (eastern white pine, I believe).

Most of my red oak is from a tree I felled fresh and stacked it on the kiln for only a couple weeks before wrapping it. The birch trees are all freshly felled, as is the beech. Some of the red oak is from a huge dead tree out back that I hauled down the mountain. The upper half of the tree hadn't started to go punky yet so I bucked and split that.

The softwood in the first kiln is all from five huge pine trees that fell in a terrible storm last November that took out a huge number of trees in my town. I bucked and split that wood this summer.

Second Kiln​
The second kiln is almost exclusively softwood that I felled and immediately stacked. It has been split and stacked from 1 month down to only days (as I filled it up before wrapping). I was a little short after the last pine tree so I finished it out with a handful of small birches that were damaged.


None of this wood was split and stacked over a month before cover it in the kiln, and some of it was less than that. Most of the wood is from freshly felled living trees and was very high MC--my moisture meter maxes out at 40% MC and all of this wood showed 39-40% when I first split and stacked it, but I did not re-test the wood (some of which was sitting there for a month or so) before wrapping it in plastic.

First Kiln 30 Day Performance​
I pulled some splits out of my first kiln from the top row through the gable vents today. The pine looks like it is pretty much ready to burn, splits ranged from 20% to 25% MC.



*Pine*

The red oak is interesting. The very center is still 38% MC, but it dropped to 24% MC only a couple inches over, and to 19% about 2" in from the end of the split (all tested on the fresh face of the cut). So it's definitely drying out but the very center is still showing high MC. This is after only about 30 days in the kiln.



*Red Oak - Center



Red Oak - 2" from End*

*Update:*

*A note on weather:*_ My part of central NH enjoyed an especially cloudy and rainy Fall this year. We had precious few days of full sun; even the sunny days tended to be partly cloudy. I believe this slowed down kiln performance._

First Kiln 90 Day Performance

At 90 days, the red oak was still reading in the mid-20s when I removed and split several pieces to test MC. The birch, however, all tested in the low teens.



*Red Oak*



*Birch*

First Kiln 110 Day Performance and Second Kiln 80 Day Performance: Finished!

I am very happy to report that after 110 days in the kiln, even with a terribly cloudy season, both the freshly felled red oak and the storm-felled red oak are below 20% MC and ready to burn.

The red oak (first kiln) averaged 18.8% MC, but no test exceeded 20% MC. 

The pine (second, later kiln) was all below 20% MC. 



*Red Oak* (note: I took this split inside and warmed it up. This meter seems to read accurately in cold weather, as it actually tested lower (18.5% MC) after warming to 70dF)



*Pine* (second kiln, 80 days)

Snow Performance

We finally had a decent snowstorm, dropped 3.5 to 4 inches the first night and about as much the second. The following photo was taken the morning after the first snow fall. 

I am happy to report that my theory proved true--the steep pitch of my kilns combined with the rope corners on each side simply dropped all of the snow off the kilns. As you can see from the undisturbed snow in the image below, I took this shot before I walked down the hill to the kilns. They dropped the snow on their own.






*Note:* all MC readings taken by performing a fresh split down the middle of a piece of firewood and taking the reading in the center of the fresh split, unless otherwise stated.


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## Woodsplitter67 (Sep 10, 2019)

I like your post.. this is a great start for seeing how much the wood will season over the course of the winter in the Northeast. I like your set up. It seems as if you've have put a lot of thought into this


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## FTG-05 (Sep 10, 2019)

What temps are you seeing inside the kilns vs the outside air temp?  Seeing any condensation on the inside of the plastic?


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## saewoody (Sep 10, 2019)

Great post. It will be interesting to see the end results.  In case no one has told you, you are going to have a chimney fire with all that pine[emoji23][emoji23][emoji23]


Sent from my iPhone using Tapatalk


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## Poindexter (Sep 10, 2019)

Cool.  Thanks for tagging me, I love seeing these various builds.  

Do you have any vertical dividers in the middles of the kilns?  One reason I went to 8 foot modules is I am just not very good at stacking and having plentiful, closely spaced fixed verticals lets me continue to stack fast and sloppy without having to restack in the summer when the wood moves and the stack topples over.


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## kennyp2339 (Sep 11, 2019)

Poindexter said:


> Do you have any vertical dividers in the middles of the kilns?


I was thinking the same thing, only for snow load. Very nicely done OP, hoping you get excellent results


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## Coalescent (Sep 11, 2019)

FTG-05 said:


> What temps are you seeing inside the kilns vs the outside air temp?  Seeing any condensation on the inside of the plastic?



For most of the day, I am seeing a pretty consistent 50dF temperature gain. On especially sunny days it almost reaches 60dF. Unfortunately, I do not get many completely sunny days here... usually the best I can hope for is partly cloudy. 

My best day so far was the one completely sunny day we've had since I finished my first kiln, temps outside were in the low 80s, and the kiln hit 139.3 (I was rooting for it to break 140, but it never did). 




Highs here have been in the 70s and the kiln temps have been hovering between 123dF and 125dF most days when I check mid-afternoon.

My first kiln had a lot of condensation at first. I intentionally spaced the plastic so it hung a couple inches away from the ends of the wood. I definitely saw condensation running down and dripping off the sides. Even took a video of one particularly impressive day. I think most moisture exits through the gable end vents, however. 

My second kiln, which I just finished a couple days ago, had a lot of condensation for the first several days. It disappeared completely the other day when the wind kicked up. With the pallet space along the bottom and the gable end vents, even a mild breeze really pushes a lot of air through the kilns. 

Maybe it's the angle, but I haven't seen droplets falling back on the wood. Condensed moisture runs to the edge and down the side, at least when I've been around to observe.


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## Coalescent (Sep 11, 2019)

Poindexter said:


> Do you have any vertical dividers in the middles of the kilns?  One reason I went to 8 foot modules is I am just not very good at stacking and having plentiful, closely spaced fixed verticals lets me continue to stack fast and sloppy without having to restack in the summer when the wood moves and the stack topples over.



It didn't occur to me to add bracing to stack the wood against. I like that idea. Hopefully these kilns will survive the drying process... one way or the other, I'll find out if my stacks will fall over as they shrink. The stacks are braced against an upright pallet at each end of the kiln.




*Inside of Second Kiln*

I do try to stack carefully... my kids form a line and bring me each split, and I set each piece myself. I (we) enjoy it. I tie string from one pallet to the other to make sure my stack isn't deforming near the middle where it's harder to gauge by eye. Also, my stacks aren't terribly tall. In the first kiln they're exactly 4 feet tall. I eyeballed the second kiln and wound up making them a tad higher, but not much. 

I'm hoping the "snow load" situation will resolve itself because my corner bracing is heavy duty paracord rope. I figure when the snow starts to pile up, it will make the rope sag and dump it all on the ground. I have no idea if this will actually work or not. I am prepared to brush the "roof" off as necessary.





*Second Kiln before Wrapping*


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## Coalescent (Sep 15, 2019)

Even this late in the year, the second kiln seems to be chugging right along. Wrapped it on the 6th, so about 9 days ago, and the freshly felled birch is already cracking open nicely on the ends.


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## SpaceBus (Sep 15, 2019)

I like the idea with the string, I'm going to have to start doing that. My stacks always end up bowing out no matter how careful I am. Unfortunately I'm also stacking on uneven ground using poles made from smaller trees and tops. I think about half of my stacks fell over with the shrinking wood. Cribbing the wood every four or five feet the full height of the stack also helps for some reason. I've heard some folks with stoves that take 24" splits that they never have settling issues. There's a five foot tall covered stack in front of my door that hasn't shifted or anything, but it's been seasoned for years now.


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## Coalescent (Sep 18, 2019)

Still very happy with how this design is performing. Today the high was 62dF here, mostly sunny this afternoon. Kilns have been cruising between 117-120dF. Right at this moment it’s 55 degrees warmer in the kilns than ambient temps, I like it!


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## Coalescent (Sep 18, 2019)

SpaceBus said:


> I like the idea with the string, I'm going to have to start doing that. My stacks always end up bowing out no matter how careful I am. Unfortunately I'm also stacking on uneven ground using poles made from smaller trees and tops. I think about half of my stacks fell over with the shrinking wood.



I will be wary of my stacks falling over, but not much I can do about it now. I didn’t realize stack stability would be a problem with stable end supports and the stacks being only 4ft high.

The only stacks I’ve personally had fall over on me were much higher and were stacked between two maple trees that swayed far more in high wind than I realized... and were on uneven ground to boot.

Then again, I’m only about five years into heating with wood (since loving wood heat as a teen, but my father took care of everything other than hauling the wood around, which was my job). I’m sure there will be many surprises in store for me...


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## SpaceBus (Sep 18, 2019)

Coalescent said:


> I will be wary of my stacks falling over, but not much I can do about it now. I didn’t realize stack stability would be a problem with stable end supports and the stacks being only 4ft high.
> 
> The only stacks I’ve personally had fall over on me were much higher and were stacked between two maple trees that swayed far more in high wind than I realized... and were on uneven ground to boot.
> 
> Then again, I’m only about five years into heating with wood (since loving wood heat as a teen, but my father took care of everything other than hauling the wood around, which was my job). I’m sure there will be many surprises in store for me...



We get a lot of wind here and I have mostly softwoods stacked, so that might be why mine fell over. I'm fairly new at this as well


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## Woodsplitter67 (Sep 19, 2019)

Take a look at my stacks in the part duex thread. I stack in the opposite direction  every once in a while  and randomly through the row. This keeps the stack more stable and level. As all stacks they will start to shift, mine started to  fall once. So next time i started to do this and my stacks really dont move
Your kiln sounds line its running well.. is there any condensation in it and how large are your vents


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## maple1 (Sep 19, 2019)

Did you put anything on the ground, under the pallets? Or are they sitting right on the grass?

I haven't tried this myself, but I think I would start by laying down some thick black plastic to stop moisture from rising up out of the ground into the pallets & wood. It would constantly be doing that. For better drying of the bottom layers of the stacks, and to help prevent or delay my pallets from rotting. Likely would also block up the pallets off the ground/plastic. But I have a strong personal distaste for rotting pallets and the nail filled mess that makes so could just be me.


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## Coalescent (Sep 21, 2019)

Woodsplitter67 said:


> Take a look at my stacks in the part duex thread. I stack in the opposite direction  every once in a while  and randomly through the row. This keeps the stack more stable and level. [...]
> Your kiln sounds line its running well.. is there any condensation in it and how large are your vents



Thanks! I’ll take a look and try out this technique.

I believe my gable-end vents are each about 4”x5”, but I will check soon.

The first kiln hasn’t had any condensation at all for some time. The second kiln (started earlier this month) has had decreasing condensation. Today was warmer and sunny. Kilns were running around 128-130 degrees. First kiln had zero condensation. Second has condensation only on the north side, none on the sunny side.

I haven’t ever observed condensation actually dripping onto the wood. I’ve seen it run down the sides and out plenty of times. Tried to capture this in some photos, below. 

Photos below at the end of this post...



maple1 said:


> Did you put anything on the ground, under the pallets? Or are they sitting right on the grass?
> [...]
> But I have a strong personal distaste for rotting pallets and the nail filled mess that makes so could just be me.



I tried to mimic @Woodsplitter67’s design as closely as possible, and I did not put anything under my kilns. My property has extremely sandy soil that drains very well, so I am hoping I will get away without it. When I unpack the kilns I will do a lot of moisture testing on the lower, mid, and upper areas to see how splits dried in different parts (and heights) of the kiln.

I get the pallets for free so I considered them a disposable part of the kiln. I can throw the leftovers on a brush pile and burn them when they go bad, but I haven’t actually done this yet. Perhaps I will share your distaste for it after actually trying it out. 

*Photos from Today*
_Note: Condensation photos are of kiln 2; temp photo from kiln 1_





*North Side Condensation - Near





North Side Condensation - Far*





*South (Sunny) Side - No Condensation, Near





South (Sunny) Side - No Condensation, Far





2:00pm (ish) Temps*


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## jaoneill (Sep 23, 2019)

A wet spring and early summer put me way behind in the firewood game this year so I am also trying the kiln dry method. In an effort to minimize handling I crisscross stack onto pallets right off the splitter (24" wood) then use tractor to transfer loaded pallets into the woodshed. This year I created a "landing" in an unused section of meadow that gets full sun all day and is open to the prevailing wind. I arranged pallets in a row, so I could wrap them in groups (16'x25' roll of plastic nicely covers 4 pallets stacked 4' high) and also stacked the pallets two high; older semi-tired ones directly on the ground with newer ones on top . Thought this would help minimize ground moisture transfer and make it a bit easier to retrieve them.  I am dealing with hickory, sugar maple and a bit of beech most of which I cut, skidded out and blocked up last summer and fall. Splits on the first 4 pallets came off the splitter at 20%-26% in the first week of August and were wrapped on 8/10. On Sept 10 I pulled two out  through the vents and they were at 14%.


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## Coalescent (Sep 24, 2019)

jaoneill said:


> A wet spring and early summer put me way behind in the firewood game this year so I am also trying the kiln dry method. In an effort to minimize handling I crisscross stack onto pallets right off the splitter (24" wood) then use tractor to transfer loaded pallets into the woodshed. This year I created a "landing" in an unused section of meadow that gets full sun all day and is open to the prevailing wind. I arranged pallets in a row, so I could wrap them in groups



This sounds fascinating, but I’m having a difficult time being sure I’m visualizing it correctly. Do you have and photos you can share? Thanks in advance!


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## jaoneill (Sep 24, 2019)

Coalescent said:


> This sounds fascinating, but I’m having a difficult time being sure I’m visualizing it correctly. Do you have and photos you can share? Thanks in advance!


Working my way back through the pile of blocks. I use the FEL with two sets of skidding tongs to hold the logs at a comfortable height for blocking them up leaving a long row of blocks that I can work through from one end, backing the tractor up every 5-6 feet. 
Very little moisture on the inside of the plastic after the first week, drips that you might see here were on the outside; it had rained that morning. There were eight pallets covered when I took these pics, wood is 24", full pallets are a bit over 4' high giving me just short of a cord on 2 pallets.


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## Coalescent (Sep 26, 2019)

I learned yesterday that the temperature of the wood split can have a dramatic effect on the results from my moisture meter. Yanking a hot piece of wood out of my kiln, splitting it and immediately testing it yielded moisture percentages higher (possibly considerably higher) than the actual moisture content.

For example, the red oak I tested at 38% that was likely about 120dF from the kiln at the time might have actually been closer to 28% according to the correction table linked below.

When I next perform my moisture tests, I will cool the wood down to room temperature before splitting and using the meter.

Sources:
Burn wise: Test Wood with a Moisture Meter
Wood Temperature Correction Table


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## Coalescent (Oct 7, 2019)

I am here to publicly thank @Woodsplitter67 and to agree with what others have said: this design works, and it works well.

My wood has been in the first kiln 2 months. It’s raining cats and dogs today, but this weekend I removed about a face cord of pine from both the front and back (north and south) stacks inside the first kiln.

Data:

Removed roughly a face cord of eastern white pine.

All of this wood tested at 38% or higher MC when I split and stacked it in the kiln.

This weekend, not a single piece tested at 20% MC. Highest test was 19% and some change. Average of all pieces tested was 17.5%.

I’ve had a LOT of heavy clouds during this past two months. Only two days of total sunshine (no clouds at all).

I will remove all of the pine as soon as I get a dry day this week and test it more thoroughly, but I’m very pleased.

Looking forward to testing the freshly felled red oak, birch, and beech in another month. 





*Frost has Arrived*







*Highest MC tested was 19.6%*


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## Coalescent (Oct 7, 2019)

First pine fire, ever. Happy to report the house is still standing even after several of these unpredictable, dangerous experiments with burning pine...


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## Woodsplitter67 (Oct 7, 2019)

Coalescent said:


> I am here to publicly thank @Woodsplitter67 and to agree with what others have said: this design works, and it works well.
> 
> My wood has been in the first kiln 2 months. It’s raining cats and dogs today, but this weekend I removed about a face cord of pine from both the front and back (north and south) stacks inside the first kiln.
> 
> ...



 Thanks for the heads up. I am glad to see it working out for you. The object of this site is to help each other and pass along Knowledge from one wood burner to the next. We all can learn somthing and also pass somthing on to one another.  Please keep posting.. om super intrested in kiln temps in December January and February.  Pine will go pretty quick as well.as poplar and black cherry.. the oak will be a little slow over the winter...thanks for the props man...


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## jaoneill (Oct 21, 2019)

Coalescent said:


> I am here to publicly thank @Woodsplitter67 and to agree with what others have said: this design works, and it works well.



I want to echo Coalescent's thank you to Woodsplitter67. My "kilns" aren't as pretty as theirs but the principal is certainly sound. Hickory in my first set of 4 pallets, covered on 8/10 are now at 14%, beech in the same batch is @ 12%, as is the hard maple, they are ready to be moved into the woodshed. Pulled a couple of hickory splits out of the second set of 4 pallets, covered on 8/30, and they were @ 16% & 18% only 6-7 weeks in. Not to shabby considering they didn't have the advantage of the "summer" heat.  I have 2 more batches covered this month, hope they get below 19%-20% before winter sets in. Blocked up another batch today. Including a few more pics of the work in progress over time: for reference, the top of the fenders on the smaller tractor are a bit over 5' high, hood on the sweet allis is over my head.
	

		
			
		

		
	














	

		
			
		

		
	
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## Woodsplitter67 (Oct 22, 2019)

jaoneill said:


> I want to echo Coalescent's thank you to Woodsplitter67. My "kilns" aren't as pretty as theirs but the principal is certainly sound. Hickory in my first set of 4 pallets, covered on 8/10 are now at 14%, beech in the same batch is @ 12%, as is the hard maple, they are ready to be moved into the woodshed. Pulled a couple of hickory splits out of the second set of 4 pallets, covered on 8/30, and they were @ 16% & 18% only 6-7 weeks in. Not to shabby considering they didn't have the advantage of the "summer" heat.  I have 2 more batches covered this month, hope they get below 19%-20% before winter sets in. Blocked up another batch today. Including a few more pics of the work in progress over time: for reference, the top of the fenders on the smaller tractor are a bit over 5' high, hood on the sweet allis is over my head.
> 
> 
> 
> ...



Thanks fo posting.  Im glad to see this working out for you.  I like your stacks i would hope that you will keep posting your results. The seasoning will slow as we get closer to winter,  but you will see results.. please post what they are..


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## jaoneill (Oct 22, 2019)

Woodsplitter67 said:


> Thanks fo posting.  Im glad to see this working out for you.  I like your stacks i would hope that you will keep posting your results. The seasoning will slow as we get closer to winter,  but you will see results.. please post what they are..


A lot of experimenting with stacking the pallets over the last few years. Started with temporary brackets to hold the splits while stacking, then banded them after stacking. This was an abject failure; by the time I went to fetch them, after the wood had dried, the bands were loose as a goose and stacks went to pieces.  Tried several other iterations before coming up with this method. Wood drying and shrinking rarely affects the stability of the stacks and, rather than band, I simply use two ratchet straps, one on each half of the pallet, for transport; easy enough to just pull straps a click or two tighter if they start to loosen up while being moved. The process has reduced my wood handling, the most time & energy consuming part of the process, by 75%.


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## maple1 (Oct 22, 2019)

I am thinking this would do even better if a good layer of good plastic was put on the ground first, under the pallets. It is always giving up moisture. I suspect it would affect the lower layers more.


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## jaoneill (Oct 22, 2019)

maple1 said:


> I am thinking this would do even better if a good layer of good plastic was put on the ground first, under the pallets. It is always giving up moisture. I suspect it would affect the lower layers more.


I actually did that under the first 2 pallets in this experiment. It seemed to make no discerable difference but probably because I used a 2 high pallet configuration. There were a few reasons for doing this. One being to get the wood further from the damp ground, another was visibility and ease of finding the fork cavity through grass or snow, a third being that I used older, compromised pallets on the ground hoping to get increased usage out of the newer ones that the wood is stacked on.


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## Woodsplitter67 (Oct 22, 2019)

jaoneill said:


> A lot of experimenting with stacking the pallets over the last few years. Started with temporary brackets to hold the splits while stacking, then banded them after stacking. This was an abject failure; by the time I went to fetch them, after the wood had dried, the bands were loose as a goose and stacks went to pieces.  Tried several other iterations before coming up with this method. Wood drying and shrinking rarely affects the stability of the stacks and, rather than band, I simply use two ratchet straps, one on each half of the pallet, for transport; easy enough to just pull straps a click or two tighter if they start to loosen up while being moved. The process has reduced my wood handling, the most time & energy consuming part of the process, by 75%.



 The reduction of processing time is huge. Im showing my neighbor the ways of the wood he is now burning dry wood has a large shed getting ready to build a second shed and has two solar Kilns.. he has remarked to me how much nicer it is to burn sub 20% wood along with the reduction of Labor to do so


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## maple1 (Oct 22, 2019)

jaoneill said:


> I actually did that under the first 2 pallets in this experiment. It seemed to make no discerable difference but probably because I used a 2 high pallet configuration. There were a few reasons for doing this. One being to get the wood further from the damp ground, another was visibility and ease of finding the fork cavity through grass or snow, a third being that I used older, compromised pallets on the ground hoping to get increased usage out of the newer ones that the wood is stacked on.



I also hate dealing with rotting pallets in any way shape or form. Nails everywhere. So at the bottom next to the ground I would likely put something else, like cinder blocks (what I actually do use) or maybe PT landscape tie things or maybe some short length of poles/logs. Even if the poles eventually rot (which they will), at least they won't be leaving nails behind.

Then again I think every tire on every wheeled thing I own has some kind of nail magnets inside....


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## jaoneill (Oct 22, 2019)

maple1 said:


> I also hate dealing with rotting pallets in any way shape or form. Nails everywhere. So at the bottom next to the ground I would likely put something else, like cinder blocks (what I actually do use) or maybe PT landscape tie things or maybe some short length of poles/logs. Even if the poles eventually rot (which they will), at least they won't be leaving nails behind.
> 
> Then again I think every tire on every wheeled thing I own has some kind of nail magnets inside....


I try to get rid of the pallets before they get that bad....


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## Jan Pijpelink (Oct 22, 2019)

I am using a solar kiln for the 2nd year, thanks to @Woodsplitter67. I agree, it works. My kiln is still up. I will be traveling till mid December and will take it down then. I have not take any MC measurements yet.


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## jaoneill (Oct 22, 2019)

Woodsplitter67 said:


> The reduction of processing time is huge. Im showing my neighbor the ways of the wood he is now burning dry wood has a large shed getting ready to build a second shed and has two solar Kilns.. he has remarked to me how much nicer it is to burn sub 20% wood along with the reduction of Labor to do so


I've been doing this for near 50 years and have always tried to improve the entire process. Started out burning almost 40 cord a year, built an air tight furnace that was one huge heat exchanger with an afterburn chamber and combuster to boot, that cut it down to 20-25 cord. Then put in oil boilers for the shoulder seasons; down to 18-20 cord. Then about 15 years ago did major improvements built a fireproof, masonry, block mechanical room off the house for the boilers and generator, pulled the twin oil boilers out of the basement, went to a wood gasification boiler and cut the usage down to 10 cord. We only heat eight of our 16 rooms most of the time, so this year I insulated the 1st floor ceilings over the heated space, should help cut usage a bit more. Have also experimented with numerous ways to cut down on the wood processing time and the above pallet method is the best I have found.


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## Woodsplitter67 (Oct 22, 2019)

jaoneill said:


> I've been doing this for near 50 years and have always tried to improve the entire process. Started out burning almost 40 cord a year, built an air tight furnace that was one huge heat exchanger with an afterburn chamber and combuster to boot, that cut it down to 20-25 cord. Then put in oil boilers for the shoulder seasons; down to 18-20 cord. Then about 15 years ago did major improvements built a fireproof, masonry, block mechanical room off the house for the boilers and generator, pulled the twin oil boilers out of the basement, went to a wood gasification boiler and cut the usage down to 10 cord. We only heat eight of our 16 rooms most of the time, so this year I insulated the 1st floor ceilings over the heated space, should help cut usage a bit more. Have also experimented with numerous ways to cut down on the wood processing time and the above pallet method is the best I have found.


 The less we handle the wood the better. I started saving labor by drying my wood in a shed insted of on racks and then moving to a shed or playing with tarps. Next was cutting tomes down on processing... i like getting the free wood.. makes me happy


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## Cfran88 (Nov 3, 2019)

I missed the original thread from Woodsplitter.  I have a few questions for anyone that knows...

What kind of plastic are you using for the kiln?  How long does it last before needing replacement?

Is there a door/entrance built in to add or remove wood? Or do you remove all the plastic them reapply it the next year after on a new batch?

Is there harm in keeping the wood in the kiln year round? Can wood be "too dry"? I was originally looking for a way to keep the wood dry (bought some wood and it's getting rained on,  no skill to build a shed). Ended up having pretty wet wood burning tonight even though MM said it was ok (the amount of water cooking was shocking). 

But I'm just starting to scrounge wood, hoping to never have problems after this year. Would love to start kiln drying before the spring rain really starts, maybe even a cord drying before the snow falls this year if I'm lucky.  

Is it safe to say with kiln drying that I don't have to get years ahead with wood? I only live on 1.4 acres so I can only use so much space before it bothers my husband, but at least 3 or 4 cords. Plus since I'm a new scrounger, unsure how much wood I will actually get next year.  We are just casual burners using an insert (unless wood turns out to be fruitful enough for me to turn down the furnace)

Any advice would be appreciated. Thanks!


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## Jan Pijpelink (Nov 3, 2019)

Cfran88 said:


> I missed the original thread from Woodsplitter.  I have a few questions for anyone that knows...
> 
> What kind of plastic are you using for the kiln?  How long does it last before needing replacement?
> 
> ...


I use 6 mill clear plastic. It stays on from mid June till late Oct./early Nov. Keeping it on all year would not harm, but in the winter it serves no purpose. Wood can be too dry, ideal is 12%-16% MC.


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## Cfran88 (Nov 3, 2019)

Jan Pijpelink said:


> I use 6 mill clear plastic. It stays on from mid June till late Oct./early Nov. Keeping it on all year would not harm, but in the winter it serves no purpose. Wood can be too dry, ideal is 12%-16% MC.



Is your wood green when it goes in?


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## jaoneill (Nov 3, 2019)

Cfran88 said:


> I missed the original thread from Woodsplitter.  I have a few questions for anyone that knows...
> 
> What kind of plastic are you using for the kiln?  How long does it last before needing replacement?
> 
> ...


I would venture to say that a "kiln" can be as simple or as elaborate as you care to make it. I did mine on order of a simple, disposable way to get this year's wood dry enough to burn. Relatively inexpensive 4 mil poly sheeting that I will dipose of when it comes off the stacks. FWIW, poly, no matter the weight, will not generally last more than a year in the weather. I know this after a lifetime using it for assorted purposes from  spring time greenhouses to temperary storm windows; the sun's UV rays render it extremely brittle after six to eight months. 
One of my younger brothers went a more elaborate route building a combination woodshed, boiler shelter, greenhouse; a pole barn with fully half sided and roofed with polycarbonate panels. He stocks the woodshed portion in the spring and once he has moved all of his garden seedlings out, closes up the doors and most of the vents and "cooks" the wood at 130-150 degrees for most of the summer. Works extremely well and it is now almost ten years since he built it and it's still in great shape.


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## Jan Pijpelink (Nov 3, 2019)

Cfran88 said:


> Is your wood green when it goes in?


Most of it. Well, not soaking wet, but not fully seasoned.


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## Woodsplitter67 (Nov 3, 2019)

Cfran88 said:


> Is your wood green when it goes in?



No.. do not put green wood in the kiln.. let it season for a few months.. its ready to kiln when the stacks start to shift is a good rule of thumb. If you want to do some reading look in my signature there are 2 links to the thread.. ill be finishing out the part deux thread this week.. just been to busy.. use the 6 mil CLEAR plastic from big box store.. or if your going to be doing alot go on line and get the greenhouse pladtic.. the plastic you get in the store will last like 3 months if your lucky.. the greenhouse stuff will last year's.. its more expensive  but will last alot longer making it cheaper in the long run


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## Woodsplitter67 (Nov 3, 2019)

If your going to be doing a kiln on a regular  basis  you may want to put together somthing less basic than mine.. mine is simple.. i leave the racks there .. stack the splits..let it sit and then wrap it around june.. unwrap it in September and tarp it.. then burn it.. keeping it simple keeps the overall time spent on wood down..


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## Woodsplitter67 (Nov 3, 2019)

Cfran88 said:


> Is your wood green when it goes in?



If your looking for a different design than mine.. more of a walk in type look up @Poindexter .. hes is a more permanent style with great results.. he may have a link or may chime in and help you out


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## Coalescent (Dec 3, 2019)

Hello all!

I updated my original post with the 90 day and 110 day performance of the first kiln, and the 80 day performance of the second kiln. 

I also added a photo showing that my kilns are shedding snow nicely. It just falls right off. I love it!

Temperature
So far, even when it's in the low teens outside with wind chills placing the temps near 0dF (we've had a few days like this already), the kilns are warming above freezing if there's any sun on them. Since the cloudy days tend to be warmer, the kilns are still above freezing pretty much every day for at least some period of time.

Watching the temps plummet at night and warm to the 50s and 60s in the kilns during the day made me wonder if this freezing/warming action might help expel the water from the center of the splits... the water in these splits freezes hard every night, expanding, then warms well above freezing during the day, liquifying and shrinking again. No idea if this speed things along or not, but am trying to devise a way to test my theory.

*Some interesting incidents that happened in the meantime--*

Wind Damage
In mid-October we had an intense windstorm (60+mph gusts) that came in from an unusual direction. The wind ripped the plastic off my newer kiln, even with the shrink wrap and lots of staples in the bottom. I re-attached it, but am considering further reinforcement next year--possibly clamping the bottom 2" between two 2x4s. On the other hand, it wasn't very difficult to fix, and it's held strong since.






*Windstorm Damage*

Wildlife
I enjoyed snapping several shots of this fellow near the kilns late in September:










*A Visitor*

Snow Arrives










*Kilns in the Snow*


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## Ihalmiut (Dec 4, 2019)

I'm doing this! I have 2 cords dry in the shed. My buddy brings me a cord of "dry 3 year oak". So its all stacked in front of my dry elm, oak, cherry. Totally not dry! So now I am going to split it some more, stack and wrap like this. I'm in Minnesota. Lots of snow already and have had some early really cold weather. Have you guys thought of black plastic?


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## Coalescent (Dec 4, 2019)

Ihalmiut said:


> Have you guys thought of black plastic?



I don’t have links handy, but I’ve seen numerous posts in my own research on these forums (and others) that suggest that black plastic does NOT work nearly as well as clear plastic.

I think the idea is that the black plastic might heat up from the sun’s energy, but it doesn’t transfer that heat energy to the wood underneath it. Clear plastic allows the sun’s radiation through, heating up the air and wood inside the kiln, but the radiation doesn’t have enough energy to escape—think of the greenhouse gas effect.

At any rate, I can say from personal experience that clear plastic works, and works well!


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## Woodsplitter67 (Dec 4, 2019)

Ihalmiut said:


> I'm doing this! I have 2 cords dry in the shed. My buddy brings me a cord of "dry 3 year oak". So its all stacked in front of my dry elm, oak, cherry. Totally not dry! So now I am going to split it some more, stack and wrap like this. I'm in Minnesota. Lots of snow already and have had some early really cold weather. Have you guys thought of black plastic?



In essence you are creating the greenhouse effect. you are making a greenhouse and basically putting wood in it. there are no green houses built with black plastic you do not want to heat the plastic you want the sun's energy to transfer to the inside of the kiln


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## Coalescent (Dec 4, 2019)

Cfran88 said:


> Is your wood green when it goes in?



One of the differences between my experiment and @Woodsplitter67’s kilns is that I was in emergency mode this year and needed to use and dry my own wood fast, because I moved recently.

Some of the wood I used was storm-felled and dead already, but most of it was very green—I felled the tree, bucked it, split it, and stacked it in the kiln. Most of this wood sat in the sun for a week or two before I wrapped the kiln, but that’s it. I think my use case is closer to @Jan Pijpelink.

I didn’t pre-season my wood before using the kilns, and they were started late in the season (August and September), yet I was still able to dry Red Oak from maxing out my moisture meter at 38-40% MC to sub-20% MC in 110 days.

I think this helps demonstrate that kilns work very well, even in less-than-ideal conditions.


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## Jan Pijpelink (Dec 4, 2019)

Coalescent said:


> One of the differences between my experiment and @Woodsplitter67’s kilns is that I was in emergency mode this year and needed to use and dry my own wood fast, because I moved recently.
> 
> Some of the wood I used was storm-felled and dead already, but most of it was very green—I felled the tree, bucked it, split it, and stacked it in the kiln. Most of this wood sat in the sun for a week or two before I wrapped the kiln, but that’s it. I think my use case is closer to @Jan Pijpelink.
> 
> ...


I C/S/S my wood in February/March. It has been in sun and wind till I wrapped the kiln in June.


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## Coalescent (Dec 4, 2019)

Jan Pijpelink said:


> I C/S/S my wood in February/March. It has been in sun and wind till I wrapped the kiln in June.



I stand corrected! Thank you for replying.

When you replied to the question of “is your wood green when it goes in?” earlier and said “Most of it. Well, not soaking wet, but not fully seasoned.” I assumed you were doing something closer to what I was doing, not 3 months of seasoning.

Apparently my kiln experiment is fairly unique in that regard.


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## Jan Pijpelink (Dec 4, 2019)

Coalescent said:


> I stand corrected! Thank you for replying.
> 
> When you replied to the question of “is your wood green when it goes in?” earlier and said “Most of it. Well, not soaking wet, but not fully seasoned.” I assumed you were doing something closer to what I was doing, not 3 months of seasoning.
> 
> Apparently my kiln experiment is fairly unique in that regard.


Wood that has been C/S/S for 3 months is still wet, in my book.


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## Woodsplitter67 (Dec 5, 2019)

i built my son a greenhouse this past September.. its not heated during the day and the temps in there show that you can dry the wood in a kiln over the winter. your observation is right that the heating inside is shorter than in the summer. i beleave that doing a kiln in winter will work and dry wood but just not as fast as in the spring, summer,early fall. the otherday it was in the upper 30s  outside with a 15 to 20mph wind inside the greenhouse it was 82 and the RH was 5%


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## Woodsplitter67 (Dec 5, 2019)

also i dont pre season my wood.. my wood that goes in the kiln is still green. i let it sit for 3 months prior to doing the kiln. this will let out an abundance of moisture from the wood. doing this will keep alot of condensation out of the kiln and aid in seasoning. when i do the kiln my wood is still in the 30s ... just not the upper 30s..


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## Coalescent (Dec 5, 2019)

Woodsplitter67 said:


> also i dont pre season my wood.. my wood that goes in the kiln is still green. i let it sit for 3 months prior to doing the kiln. this will let out an abundance of moisture from the wood. doing this will keep alot of condensation out of the kiln and aid in seasoning. when i do the kiln my wood is still in the 30s ... just not the upper 30s..



Hello @Jan Pijpelink  and @Woodsplitter67 ,

I am sorry I misrepresented you guys in my last post. Serves me right for trying to multitask and write a post at the same time as trying to attend to something else that needed doing.

My goal was to convey that I put my wood into the kilns wet and green, more so than what I understood you to have done. I didn't mean to suggest that you had truly seasoned your wood first, only that you'd left it out for a while. 

I also want to make it clear to anyone else reading this thread that I think leaving the wood out for a bit is a better idea. I did what I did only because I was out of time and was determined to avoid buying firewood from someone else.

My family and I benefited enormously from the projects you've shared with this community... I have almost 5 cords of sub-20% wood to burn thanks to your shared designs! My purpose with this thread was to share my experience and provide a little more data and one more voice saying "Hey, I tried this too, and it really works... even in wet, cold central NH in the Fall!" 

I wanted to strike-through my previous post and add these comments there, but I seem to have lost my ability to edit my posts.


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## SpaceBus (Dec 5, 2019)

That's awesome, I wouldn't have thought it possible. I'd like to build a permanent kiln with some leftover windows and sliding door panels if even just to kill all the bugs.


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## Jan Pijpelink (Dec 5, 2019)

Coalescent said:


> Hello @Jan Pijpelink  and @Woodsplitter67 ,
> 
> I am sorry I misrepresented you guys in my last post. Serves me right for trying to multitask and write a post at the same time as trying to attend to something else that needed doing.
> 
> ...


Thanks. I got my tricks from @Woodsplitter67 and @Poindexter. They taught me a lot. Anyway, what works for me is this:
1- Cut, split and stack wood in the first 3 months of the year.
2- Let it expose to sun and wind for 3+ months.
3- Then wrap the kiln around the stack with a few breathing holes at the top of the kiln.
4- Leave it there till Oct/Nov.
5- It will be below 15%.

Note: All depends on location, position to sun and wind, and local weather conditions.


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## Poindexter (Dec 6, 2019)

What I do with mine is keep the internal kiln temperature under +95dF until the water is out all of the sap tubules.  That bit of moisture can be done in two weeks or so of dry weather - the water molecules can wick themselves to the ends of the splits via capillary action just running up and down the tubules that are vertical in the standing tree trunk.  Maybe longer for really knotty stuff or burls down by the stump end of the donor log, but pretty much two weeks.

Once the free water is out of tubules all that is left is the bound water inside the individual cells, mostly bound up in the cellulose we want to burn later.  This is your fiber saturation point.  Water out of the sap tubes, but otherwise green wet wood.  Typically your meter will show you right about 30% MC give or take for most species, IIRC 28-32% MC covers 85% of wood species' FSP or fiber saturation point.

Without a meter, if your stack is still standing tall and not shifting around, you are still above FSP.  Once your split starts drying below FSP, that is the tubes are empty and you are getting bound water out from inside individual cells, that is when your stacks start moving around because now with water coming out of the cells, the cells  will change size and shape so the split will start changing size and shape.

Locally I just make sure i have everything stacked by Saint Patricks Day, March 17th.  I just load em up and close them up.  Consistently for me my stacks are well below FSP before the weather is hot enough to get my kilns hot enough to worry.

The concern for me is if the kiln gets too hot while there is still water in the sap tubules the ends of the tubes might shrink closed and trap water in there.  I came up with 95dF from a scientific article about drying lumber that I linked to in my second kiln thread.

The edit button goes away a few hours after a post is first posted.  I dunno how many hours.


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## Woodsplitter67 (Dec 6, 2019)

Coalescent said:


> Hello @Jan Pijpelink  and @Woodsplitter67 ,
> 
> I am sorry I misrepresented you guys in my last post. Serves me right for trying to multitask and write a post at the same time as trying to attend to something else that needed doing.
> 
> ...



i want you to know that i am not upset in any way.. thank  you  for the correction. o just wanted to make sure that people know that my wood is still pretty green when i do the kiln.. its just not freshly cut and put in the kiln. im happy that this is working out for youand your sitting on 5 cords ready to bur with such a late start.. there have been many posts so fart of my woods wet.. now what..


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## jaoneill (Dec 8, 2019)

Update on my experience this fall. Wood was blocked up in March/April, split, stacked on pallets and wrapped in groups of 4. Four groups with 1/2 cord on each pallet, 8 cord total, in full sun dawn til dusk. Moisture was averaging mid-twenties when split. First group was split and wrapped in early August, uncovered and put in the shed mid October at 12%-15%. Last group had only been wrapped for about 5 weeks when we also had 65mph winds that completely shredded all of the plastic.  All were below 20% but the the final group, and they  were down in the 20% neighborhood So I called it a day and moved all but a few pallets into the shed last weekend, and top covered those few until I have more room inside. To my way of thinking it was, all in all, a resounding success!


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## Chas0218 (Dec 11, 2019)

Anyone dabble with the clear poly carbonate panels? I would imagine it would have the same effect. I was thinking of building a solar kiln to dry rough sawn boards. The solar kilns I have seen are all painted black interiors with clear panels on the southern exposure side. Wouldn't this same concept work but for firewood? I'm just kind of thinking out loud but wouldn't mind input from you guys. I mean nothing venture nothing gained.


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## Woodsplitter67 (Dec 11, 2019)

Chas0218 said:


> Anyone dabble with the clear poly carbonate panels? I would imagine it would have the same effect. I was thinking of building a solar kiln to dry rough sawn boards. The solar kilns I have seen are all painted black interiors with clear panels on the southern exposure side. Wouldn't this same concept work but for firewood? I'm just kind of thinking out loud but wouldn't mind input from you guys. I mean nothing venture nothing gained.



i just built a polly carb greenhouse for my son.. basically your building a greenhouse and putting wood in it. the pollycarb works great and it really gets warm in there.. u can use polly for what you want to do.. i did mine in the 8mm panels


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## Woodsplitter67 (Dec 11, 2019)

Chas0218 said:


> Anyone dabble with the clear poly carbonate panels? I would imagine it would have the same effect. I was thinking of building a solar kiln to dry rough sawn boards. The solar kilns I have seen are all painted black interiors with clear panels on the southern exposure side. Wouldn't this same concept work but for firewood? I'm just kind of thinking out loud but wouldn't mind input from you guys. I mean nothing venture nothing gained.




post 51 has a pick of the temp in the greenhouse with the RH also


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## Chas0218 (Dec 12, 2019)

Woodsplitter67 said:


> i just built a polly carb greenhouse for my son.. basically your building a greenhouse and putting wood in it. the pollycarb works great and it really gets warm in there.. u can use polly for what you want to do.. i did mine in the 8mm panels


Good to know Maybe I'll just build a greenhouse. My wife has talked about it for a while we just haven't dove in. I'd like to build it big enough to drive a tractor with forks  in and pick up a stack then put in a new one. You've really got me thinking about a hoophouse style greenhouse. We have a spot at the bottom of our hill in the valley that gets sun 1st and last of the day.


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## peakbagger (Dec 12, 2019)

HomeDepot in my area stocks the UV resistant polycarbonate panels. I have been tempted to do a hybrid kiln one of these days with polycarbonate on the sunny side and then regular plastic film on the shady sides. I have to be careful that whatever I build is not a "permanent structure" as our local tax assessor will slap a value on it. I already put roofing over my stacks that is supported by two by fours screwed into the ends of firewood with three "rafters" running from the front to back of the stack so expect I could argue that as long as its on pallets and the supports are off the actual stacked firewood I should be okay.  My guess is polycarbonate on the roof with some low pitch with a sheet to two of polycarbonate on the front with a slight overhang from the roof over the vertical walls and an adjustable gap between the top of the wall and the roof.  Years ago I saw thermal temp dampers that didn't require power to vent greenhouses but the ones I find on the web look too big. 

The trade off for polycarbonate sheets is they add infiltration compared to continuous wrap of plastic.


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## weatherguy (Dec 13, 2019)

Chas0218 said:


> Good to know Maybe I'll just build a greenhouse. My wife has talked about it for a while we just haven't dove in. I'd like to build it big enough to drive a tractor with forks  in and pick up a stack then put in a new one. You've really got me thinking about a hoophouse style greenhouse. We have a spot at the bottom of our hill in the valley that gets sun 1st and last of the day.


I bet a hoop style greenhouse would work great, I'd like to build one that could withstand winter snow and less moving of wood.


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## Vikestand (Dec 13, 2019)

Dude I am jealous of your view!


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## spudman99 (Dec 13, 2019)

Slightly off topic but related.  I just built this wood rack with polycarbonate roof.  Used pallets and 2x4's.  With a bit of blocking on the base to make a pallet slightly wider than the double stacks, this could be modified to secure poly on all sides.  HD sells the panels at $11 for an 8'  length that is 24" wide.   Could probably make a full greenhouse for under $75 out the door.


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## Woodsplitter67 (Dec 13, 2019)

spudman99 said:


> Slightly off topic but related.  I just built this wood rack with polycarbonate roof.  Used pallets and 2x4's.  With a bit of blocking on the base to make a pallet slightly wider than the double stacks, this could be modified to secure poly on all sides.  HD sells the panels at $11 for an 8'  length that is 24" wide.   Could probably make a full greenhouse for under $75 out the door.
> 
> View attachment 253391
> View attachment 253392
> View attachment 253393



what your using is not whats to be used for a greenhouse... a greenhouse pollycarb is a 2 wall polly sheet. what you have is  different material


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## spudman99 (Dec 14, 2019)

Woodsplitter67 said:


> what your using is not whats to be used for a greenhouse... a greenhouse pollycarb is a 2 wall polly sheet. what you have is  different material



You are correct and thanks.  What I used was a polycarbonate plastic panel from Lowes.


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## SpaceBus (Dec 14, 2019)

spudman99 said:


> You are correct and thanks.  What I used was a polycarbonate plastic panel from Lowes.
> 
> View attachment 253472


How well do you think it will handle the snow?


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## Woodsplitter67 (Dec 14, 2019)

SpaceBus said:


> How well do you think it will handle the snow?



i found the polly carb panels to be quite ridged.. but this is for a thicker panel.. so the 2mm is not as ridged as an 8mm both are double wall..


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## spudman99 (Dec 16, 2019)

SpaceBus said:


> How well do you think it will handle the snow?


 
Dunno yet.  I have the panels on a 5% slope with a 2x4 cross beam.  In full sun I'm hoping the snow pack will melt it off quicker.  I have the wood stacked tight to the top so the cross beams should not sag with snow weight.  Panels are cut in half so it takes 2 panels for a full 8' crib.  Haven't had any decent snow around here yet.


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