# basement wall insulation - help me avoid a mistake



## iron (Jul 28, 2016)

in the upcoming months, i will be remodeling our basement. there are two primary goals:
1. seismic retrofit (basically involves anchors bolts, tie down straps, and adding plywood to the interior face of cripple walls)
2. improve insulation

my insulation scheme is as follows:
- 1" XPS on the floor with 3/4" tongue and groove plywood over it (for carpet)
- concrete foundation wall gets 2" of XPS or spray foam (closed cell)
- cripple walls get R13 faced batt insulation
- insulate joist cavities at the rim board as well as general air sealing

please take a look at this image for my plan:




i have several question areas which are indicated by the dark dashed boxes. let's start from the top and work down.

1. at the interface of the joists and the wall, how should i best insulate this? i know you can spray foam or XPS foam the cavity, but i'm curious about transitions to other wall/ceiling surfaces. it seems to me i need to fully cover any potential cold surfaces to prevent cold air from contacting my future finished interior wall.

2. at the transition between cripple wall and concrete foundation wall, what should i do here? i've seen some suggest just putting a vapor barrier over the cripple wall (like 6 mil plastic) and then taping it to the XPS foam (assuming i use XPS and not spray foam). but, that method seems inadequate to me since it feels like that's a good spot for cold air in the winter to come off the concrete, then reach the backside of the interior (heated) wall.

3. where the floor insulation meets the concrete wall insulation. should i leave a gap or make it tight? some say that a gap is good in the event it gets moist. as far as i can tell, we have a pretty dry basement, though there is a musty smell (likely in the floor which i'll be ripping out). no matter what, i plan to hold the subfloor a few inches away from the wall insulation.

bonus question:
on the surface of the interior plywood used for the seismic retrofitting, should i just spray foam or XPS foam over this to create a vapor barrier? this is my biggest concern of the project. i do not want to inadvertently create reverse vapor barriers or not insulate correctly.

i can see moisture/cool air getting in through the cripple wall foundation plate and into the cripple wall (which will have batt insulation). once there, it seems easy enough for it to permeate through gaps and the plywood and then reach the back of the interior (heated) wall. i feel like foaming over the entire wall surface could avoid this potential issue, but then i am worried about doing something stupid like trapping too much moisture in the batt insulation or reversing a vapor barrier. please see the pic below. this kind of "insulation" is underneath my siding. i call it structural cardboard --- it's about 1/8" thick and has a silver facing.


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## vinny11950 (Jul 28, 2016)

You have a lot going on here, Iron.

Basements are big deals because you are constantly fighting moisture and water damage, while keeping access to all the plumbing and electrical you need access to.

Honestly, in your region, I would not worry about losing too much heat from the floor.  I would do away with the carpet and T&G plywood and floor foam insulation because one leaky pipe at the wrong time will have you ripping all that out.  Leave the concrete bare.  Worry more about air sealing the basement and controlling the air that comes in and goes out.  In my basement, I try to open the windows only when the humidity is low.  Still, they used all the wrong materials and now it smells moldy in the summer.  Sheetrock has to be ripped out.

Anyway, for your cripple wall, I would continue with the 2 inch XPS, sealed seams with tape all the way to the bottom of the floor joists where they meet the insulation in the joist bays..  And before putting it up, seal the cripple wall as much as possible with foam - gaps and cracks and holes.

If you do decide to put the foam on the floor, I don't think having the foam go to the walls or leaving a gap will make much difference.  The foam can handle the contact and a small gap at the same time will not do much to dry the floor beneath should it ever get wet.

Anyway, I recommend that after you demo the basement, leave it bare for a few months (a year to see all the seasons would be best), just to learn the what's happens at the concrete walls - do they weep, leak or have efflorescent spots?  Any of those issues should be addressed first before rebuilding it.

I know they are expensive, but those basement wall panels from Dow sure look nice and functional for a basement.


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## begreen (Jul 28, 2016)

I'm not a builder but for question #1 would Roxul batt insulation sections work there. 

Note that this electrical box needs to move so that the wire can be stapled within 6" of the box.


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## iron (Jul 29, 2016)

we're doing carpet for sure. the basement will be a living room/play area for soon to be future kids (<6 weeks) and we will have a guest bedroom and bathroom down there. it needs to be comfortable. 

there currently is carpet in a small section. i believe it's just laid over 6mil plastic. i will pull it out and give it the smell test.

BG: my buddy the electrician either didn't care about that wire not being stapled, or fixed it before we finished up the wall. in either case, there's tile and such already installed, so it is where it is


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## iron (Jul 29, 2016)

also, could anyone speak about heat recovery ventilators? our house is 1979 construction, but with recent air sealing and insulation efforts on my part, i suspect it's going to be much tighter. our windows are all new (2011) and exterior doors as well. i'm starting to think we may benefit from a HRV. 

heating is provided by an electric furnace with an old heat pump. of course, our goal is to heat 100% with wood this upcoming year, but we'll see how that goes. i do see using the recirc fans from the furnace to move air from the warm upstairs to the basement. 

thanks all!


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## LowbanksArcher (Jul 29, 2016)

I'm planning a similar installation for the flooring, except I plan to lay a basement foundation wrap membrane down first under the insulation. The stuff with the dimples that lets the concrete to breath and will channel potential moisture away. This will mimic the design of the DRIcore/Amdry subfloor panels but save some $.


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## vinny11950 (Jul 29, 2016)

Iron, you probably found this link already but in case you haven't, enjoy the reading.

http://buildingscience.com/documents/digests/bsd-103-understanding-basements


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## sportbikerider78 (Jul 29, 2016)

I'm doing this as well.  I will be following this video to a "T".  But I will be using double faced foil polyiso and taping seams and sealing it to the wall with an adhesive.   I know that polyiso is not 100% a vapor barrier but it is pretty darn good and way better than bare concrete.  My objective is not to finish it, but to decrease moisture and cold from coming through the wall.  

http://www.thisoldhouse.com/toh/video/0,,20503345,00.html


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## iron (Jul 29, 2016)

yes, i read the buildingscience articles. 

i also came across a great site where the author responds to every question/comment. it's pretty amazing. 

http://www.homeconstructionimprovement.com/vapor-barriers-for-basement-insulation/3/
http://www.homeconstructionimprovement.com/vapor-barriers-for-basement-insulation/
http://www.homeconstructionimprovement.com/how-to-insulate-a-concrete-floor/
http://www.homeconstructionimprovement.com/basement-insulation-guide/


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## moey (Jul 31, 2016)

I used 2" XPS on my walls. I glued/attached them to the wall with "great stuff" and  1*4s with 3.5" concrete screws. Then put drywall up attached to the 1*4s. Basement is much warmer and much less humid now. I didnt tape the joints I would just fill them with great stuff when I did the adjoining section. 

If your finishing your basement ( I was not ) I would run some serious numbers on how much it would cost to put the 2*4 frame up to the wall with a one inch gap and have 4 1/2 spray foam done. XPS is pricey and its a lot of labor drilling holes. Adding the extra R-13 in the walls is not saving you much money at the end of day. 

A 4*8 panel drywall XPS boards and screws ended costing me about $35 and thats was using 10% off coupons and any way I could get a discount at lowes.


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## gzecc (Aug 3, 2016)

For fire code the ceiling drywall need to extend past the wall top plate to the foundation sill. Easy to do prior to building the wall. Not so much after.


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## iron (Aug 11, 2016)

it looks like i'll be doing either 2" or 3" of CCF sprayed by a contractor. quote came in very reasonable, especially considering the time tradeoff. 

one question: i know i have some water lines and such that run pretty close to an exterior wall. if those are too close to the future interior plywood face (plywood will be on the exterior wall studs, on the inside of the room), should i have them spray right over it? 

followup related question: if my water lines are in the stud cavities (to be insulated with R11 or R13 and then covered with plywood), and then i have foam sprayed over the plywood, are those lines at risk of freezing since they'll be very isolated from a heated space (interior sheetrock wall, 2-3" CCF, plywood, and R11)?


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## Buzz Saw (Aug 11, 2016)

iron said:


> it looks like i'll be doing either 2" or 3" of CCF sprayed by a contractor. quote came in very reasonable, especially considering the time tradeoff.
> 
> one question: i know i have some water lines and such that run pretty close to an exterior wall. if those are too close to the future interior plywood face (plywood will be on the exterior wall studs, on the inside of the room), should i have them spray right over it?
> 
> followup related question: if my water lines are in the stud cavities (to be insulated with R11 or R13 and then covered with plywood), and then i have foam sprayed over the plywood, are those lines at risk of freezing since they'll be very isolated from a heated space (interior sheetrock wall, 2-3" CCF, plywood, and R11)?



Can you reroute the water lines to the inside?  With some PEX it wouldn't be much work ( Easy to say from my house [emoji12] ).

Why batt insulation then spary foam? Why not spray foam in the stud cavity?  

Maybe I missed something....

Sent from my SM-G900V using Tapatalk


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## iron (Aug 11, 2016)

i'm performing a seismic retrofit. this involves adding plywood sheathing to the inside face of the studs. it's going to take me a few weeks to complete all of this. it's recommended to not leave your walls without drywall since that is a bit of a stabilizer. therefore, i will be doing sequential demo (demo, clean, retrofit, and repeat) until everything is retrofitted. once it's retrofitted, i will hire out the spray foam insulation for a single day's work --- mobilization is the highest cost. 

also, because of the junction between plywood and concrete foundation walls, i believe it will make more sense to spray foam on the plywood down to the floor rather than in the cavities then down to the floor since i will need access to install the plywood to the sill plate (very critical)


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## Buzz Saw (Aug 11, 2016)

I'm going to have to trust you on this one. I know nothing about seismic structure building.  We don't have that stuff here in Ohio....

Sent from my SM-G900V using Tapatalk


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## iron (Sep 8, 2016)

one more question:

i was all set to pull the trigger on getting the closed cell foam installed, but then read this:
http://www.greenspirationhome.com/sprayed-foam-insulation-why-homeowners-must-proceed-with-caution/

my wife is nearly 9 months pregnant, so the idea of having the basement sprayed in the next week or two and then having horrible chemical smells (possibly dangerous) is deeply concerning to me. i understand that most of these issues are contractor-related installation methods, but still.

price for 464SF of spray foam @ 3" thick is $1800, so $3.90SF. i can buy 3" XPS for about $1.26/SF. add in some great stuff and manual labor and not worry about possible chemical smell issues....

hmm.

i would love to hear your thoughts on this (soon!).


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## drz1050 (Sep 9, 2016)

I've also heard those complaints about the smell/ outgassing.. it seems they're all in cases where the foam was sprayed too thick. From what I've read, you can only spray 2" of closed cell foam at a time. If you go thicker than this, you're risking the foam not curing completely, and that's what gives you the smell. 

Regarding the water lines- how deep is your basement? Is the entire basement under grade, or is there an exposed wall? If the basement is deeper than the frost line in your climate, those pipes won't freeze.


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## semipro (Sep 9, 2016)

There are a lot of stories out there about nuisance out-gassing from sprayed foam.  I think even the most reputable installers have had issues with bad batches of chemical components, bad mixing valves, etc.  Its definitely something to take into consideration.
That's one reason I went with foam XPS board in our basement. 
I'm a big fan of Roxul also but had one batch that had ammonia-like odor problems.  I've had no problems with recent purchases.


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## DickRussell (Sep 9, 2016)

[QUOTE="iron, post: 2091368, member: 46385"..... it's recommended to not leave your walls without drywall since that is a bit of a stabilizer.also, because of the junction between p
..... since i will need access to install the plywood to the sill plate (very critical)[/QUOTE]

I'm inclined to suggest skipping the spray foam and do it all with rigid board foam. Applying it to the concrete foundation is straightforward, and even easier onto the studs of the cripple wall. I wouldn't use sheet polyethylene anywhere in the wall assembly, as that would preclude any drying to the interior. Even 2" XPS has some low permeability, somewhere around 0.6 perm, whereas poly is a tenth that, essentially a vapor barrier, rather than a class II retarder. I might also be inclined to rip out that foil-covered 1/8" cardboard stuff. If that is a foil surface, it would would be a vapor barrier by itself, and on the wrong side of things. The shiny surface perhaps is intended as a radiant barrier, but if you put insulation right up against it then you lose the radiant barrier property; it needs an air gap to be effective. I agree with recommendations by others to air seal carefully at the sill area on top of the concrete foundation, using caulk or can foam after the plywood goes up over the studs. Seal also where the plywood meets the ceiling.


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## vinny11950 (Sep 9, 2016)

Yeah, I have read about a few horror stories with spray foam insulation.  Either the installer screws up, the chemicals are bad, or some time in the near future we find out the bad health effects of these products.

I would go the foam board route instead.  Make sure you buy a reputable brand, maybe even Google it and see what hits you get.  Can't be too careful.   These boards are supposed to be inert so no off gassing (unless they burn).  But then you have to cover them to be code compliant so check your building code department and see what they suggest.


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## iron (Sep 13, 2016)

semi-related question:

i know a lot of people that install rigid foam on the floor followed by a wood subfloor will use tapcons to screw things down. after installing a few tapcons in my concrete for other purposes, i've learned that they do not work well for me unless the hole is perfectly clean. even then, it seems like it's hit or miss. therefore, i'm thinking that instead of using tapcons, i would just do the following:
1 use some great stuff spray foam, spray the backside of the rigid foam
2. place on ground and put on temporary counterweight 'til it sets
3. spray foam on backside of plywood
4. place on foam and put on temporary counterweight 'til it sets

think this is a problematic approach? the biggest drawback i see is that with the tongue and groove plywood, i wouldn't be able to pound it into place as easily.


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## sportbikerider78 (Sep 13, 2016)

vinny11950 said:


> Yeah, I have read about a few horror stories with spray foam insulation.  Either the installer screws up, the chemicals are bad, or some time in the near future we find out the bad health effects of these products.
> 
> I would go the foam board route instead.  Make sure you buy a reputable brand, maybe even Google it and see what hits you get.  Can't be too careful.   These boards are supposed to be inert so no off gassing (unless they burn).  But then you have to cover them to be code compliant so check your building code department and see what they suggest.


From what I have read, on covered XPS and EPS aren't code compliant.  But foil covered poly iso is compliant.  It makes sense.  Foil is spark resistant.  
If anyone has any other input, I'd like to hear it.  In the next month or so, I'm buying foil iso and doing the walls...and plan to leave uncovered.


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## iron (Sep 13, 2016)

IIRC, you can have issues with the foil surfaces on concrete.

also, with the polyiso, i believe it performs horribly at cold temperatures. at normal temps, it does fine and is slightly better than XPS. at lower temps, it's R-value drops from 6-something down to 2-something.

i'm planning to build a wall in front of my foam, so XPS is the way to go for sure (if i don't do spray foam)


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## sportbikerider78 (Sep 13, 2016)

Could you elaborate?  Everything about poly iso up against concrete is fine, as long as it is foil faced and air sealed along the perimeter.

My basement is 40-65F, so never really cold or really hot.


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## vinny11950 (Sep 13, 2016)

iron said:


> semi-related question:
> 
> i know a lot of people that install rigid foam on the floor followed by a wood subfloor will use tapcons to screw things down. after installing a few tapcons in my concrete for other purposes, i've learned that they do not work well for me unless the hole is perfectly clean. even then, it seems like it's hit or miss. therefore, i'm thinking that instead of using tapcons, i would just do the following:
> 1 use some great stuff spray foam, spray the backside of the rigid foam
> ...



Putting great stuff on the backside of the rigid foam and the plywood sounds like a big old mess.  The few times I have worked with it, it has been a mess.  Not to mention the foam expanding.... Will it cause bumps in different areas of the board?  Also consider once you spray that stuff on the concrete floor it is not coming off easily, so you can forget about exposing the concrete floor ever again.


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## iron (Sep 13, 2016)

i may be misremembering (been reading a lot about a lot of different subjects of late), but seem to recall something iffy about foil and concrete. i could be wrong. 

here's info on the polyiso r-value: http://www.energyvanguard.com/blog-...s-The-R-Value-of-Insulation-Is-Not-a-Constant


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## moey (Sep 13, 2016)

iron said:


> one more question:
> 
> i was all set to pull the trigger on getting the closed cell foam installed, but then read this:
> http://www.greenspirationhome.com/sprayed-foam-insulation-why-homeowners-must-proceed-with-caution/
> ...



I would not have someone spray foam if my wife is 9 months pregnant. I don't care what a company tells you. 

Hanging all that XPS is a lot of work keep that in mind its not a weekend project its a several weekend project. Don't forget to add the cost in for the screws and boards to hang up the XPS with they add up quick concrete screws are not cheap specially the 4 inch ones you will need.


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## velvetfoot (Sep 15, 2016)

Not sure why the tapcons won't work in the floor.  I used a bunch in the walls when I installed xps boards.

Great Stuff expands, so I don't think it'd work as a glue without causing lumps.


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## moey (Sep 15, 2016)

velvetfoot said:


> Not sure why the tapcons won't work in the floor.  I used a bunch in the walls when I installed xps boards.
> 
> Great Stuff expands, so I don't think it'd work as a glue without causing lumps.



I never experienced anykind of lumps but I did have a 1x4 ontop of where the great stuff was with plenty of tapcon screws. It tended to take the easiest path and flattened out like a pancake. I suspect if you used a lot though it would cause problems.


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## velvetfoot (Sep 15, 2016)

Another thing, from what I've experienced, I'm not so sure how sturdy a glued only connection would be for the xps.  It seems to me that only the surface adheres and can be peeled off.


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## semipro (Sep 16, 2016)

I used the Loctite PL300 foam board adhesive to attach XPS to my poured concrete walls.  I sealed between boards and around the edges with spray foam.  In most places stud walls were built in front of the foam board so detachment is a non issue.  In one place though, because additional clearance was needed to comply with code, I used only the PL300 adhesive between concrete and XPS and applied mold-resistant drywall on the interior with the same adhesive.  Its been about 2 years since and everything is still holding together as well as day 1 (which was great).


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## sportbikerider78 (Sep 16, 2016)

velvetfoot said:


> Another thing, from what I've experienced, I'm not so sure how sturdy a glued only connection would be for the xps.  It seems to me that only the surface adheres and can be peeled off.


Adhesives are absolutely incredible these days.  Large surface area (like a sheet of insulation board) and adhesives are a match made in heaven.  Done right, you'll have zero issues.  

I would certainly try the low expansion Great Stuff foam and see what happens.  Do a 1x1 sheet and see what happens.  

Off topic....
I work in the plastics industry as an engineering manager.  We repair broken carbon fiber sections of high speed automation equipment with epoxy and zero mechanical fasteners.  It works like a charm and we never have failures because of that epoxy bond breaking.  If you ever need an incredible 2 part epoxy, look up "Scotch Weld 2216" or one more applicable to your task.


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## velvetfoot (Sep 16, 2016)

I still think you'd want to tapcon the plywood through the foam into the concrete.


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## iron (Sep 29, 2016)

well, so far i'm 80% done with the floor using 1.5" foam and 3/4" advantec subfloor. i've been using spray foam cans to attach the foam boards to the concrete. weight it down for 20 mins while i work on something else (mostly the subfloor), then put on subfloor using more spray foam and weights. so far so good. no tapcons. no anything. no break in the vapor barrier. 

to get the tongue and groove sheathing fully seated, i've used a 12lb maul to bang things together and haven't budged the spray-foamed foam or sheathing, so i think i'm good. hopefully it doesn't loosen up over time, but if it does, it's not like things will shift anyway.

i will eventually post some pics.


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## velvetfoot (Sep 29, 2016)

A lot easier than gluing it to the walls, for sure.


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## iron (Sep 29, 2016)

velvetfoot said:


> A lot easier than gluing it to the walls, for sure.


yep, but i have a decent idea in mind for the walls. plus, flat doesn't matter as much for the walls since i'm building a 2x4 wall in front of the foam once it's done. i just need to worry about the air seal.


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## iron (Sep 29, 2016)

one other question:

for my fireplace upstairs, it sits in an alcove (though flush on the finished surface). the basement has the same arrangement geometrically, but with no fireplace/stove. we are planning to finish it off with drywall and put the TV there.

i want to know if it's okay for me to put foam insulation on the underside of the upstairs fireplace floor. see pic. i cannot imagine it would be an issue, but wanted to see if you could see any pitfalls.


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## vinny11950 (Sep 29, 2016)

Pack it tight with Roxul and don't worry about it.


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## iron (Oct 4, 2016)

gzecc said:


> For fire code the ceiling drywall need to extend past the wall top plate to the foundation sill. Easy to do prior to building the wall. Not so much after.



question for you on this item:

are you saying that my ceiling drywall should run all the way from the inside of the room to the top plate of the cripple wall (which is supporting the upstairs rim/joists) and then i butt my XPS into it? essentially, i would have a 5/8" discontinuous area in my XPS insulation for the entire perimeter of the house???

i read some other articles where people mentioned this firecode requirement. some seem to say yes, the drywall goes to the wall. others say that the foam should run all the way up and create a continuous insulation layer, and then drywall can butt into it before you frame your wall. 

i also read that you would probably also need a horizontal fireblock every 10ft horizontal (same thing - it would be a break in the insulation). and, you need fireblock at all vertical and horizontal chases. 

seems like a lot of work!


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## iron (Oct 9, 2016)

also, general question for anyone still paying attention: one of my floor joists is very close to the exterior wall. there's about a 3-4" gap between the joist and rim board. it's going to be nearly impossible for me to jam up a piece of XPS and spray foam it. is it okay if i just caulk the edges along the rim board and then stuff full of batt insulation? it'll still be a PITA, but probably easier and less messy. thoughts?


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## vinny11950 (Oct 9, 2016)

So the rim board and the joist are running parallel?  If so, your solution should work.  As long as you close air gaps and insulate you should be fine.


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## iron (Oct 9, 2016)

vinny11950 said:


> So the rim board and the joist are running parallel?  If so, your solution should work.  As long as you close air gaps and insulate you should be fine.


correct, they are parallel for about 40' with a 3-4" gap


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## vinny11950 (Oct 10, 2016)

Okay...  I imagine it will be tough aiming the spray foam straw at the bottom of the rim board where it meets the sill plate.  Maybe something like this:


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## iron (Oct 10, 2016)

vinny11950 said:


> Okay...  I imagine it will be tough aiming the spray foam straw at the bottom of the rim board where it meets the sill plate.  Maybe something like this:




yeah, i've been using a hose on other areas - though plastic tubing, not electrical wire sheathing. it sucks too. maybe the electrical wire works better...


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## maple1 (Jan 18, 2017)

Thinking about doing some of this work, before next winter. Found this thread - was a good one with some good info in it.

Just wondering how the project went, and maybe any other techniques/materials you ended up using that weren't posted? Or any ideas anyone else has to add. I have part of my basement 'done' - put some 1-1/2" foam boards up years ago, the ones that had the strapping grooves molded into them. Fastened with those Remington .22 shell fastener thingies thru the strapping - that part was fun, gunpowder smell in the basement, yahoo. But still have maybe 1/6 of it with bare concrete still, basement windows that now need replacing, and never did put anything over the foam that is there. So want to try to give it a going over.


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## iron (Jan 18, 2017)

i found the insulation process to be very tedious and annoying. issues i ha d:
1. the step between my foundation wall (concrete) and exterior timber wall (2x4) was such that i had to cut all my pieces at that location and create a joint/step in the insulation. doubled/tripled the effort there
2. insulating the rim joist was a serious PITA for my case b/c one end had a 1ft cantilevered floor overhead and the other end had all my electrical and plumbing running right next to the rim board. really tough to get into those spots
3. there's still an air gap between the foam and the wood due to imperfect framing and typical irregularities. i ended up "air sealing" this using silver foil tape. definitely made a difference.

in the long run, i'm sure it'll be a good investment. but, it definitely dragged on for me. demoing the basement, doing a seismic retrofit, and framing new interior walls has been enjoyable. the foam part, not so much. cost-wise, i probably saved $400 (20%) versus closed cell spray foam. however, due to concerns about off-gassing from the CCF, and having a newborn in the house, i opted for the XPS approach.

for the floors, i used 1.5" XPS with 3/4" T&G advantech OSB sheathing. both are great. i glued foam to concrete and OSB to foam using spray foam.

for the walls, i used 3" XPS. in the 2x4 walls, i reinstalled the r11 fiberglass insulation that was previously in the walls i demoed.

i am a few weeks away from drywalling. i plan to toss in some roxul into certain areas (mainly the rimboard area since i only got 1.5" foam in there)

trimming out the windows and doors will be interesting. with the wall thickness and foam thickness plus the offset of the interior walls, i'm looking at perhaps 12-14" of casing.


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## lml999 (Jan 18, 2017)

Looks like some tidy work. Did you ever go with an HRV? I just had one installed last week, happy to talk about it..


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## iron (Jan 19, 2017)

lml999 said:


> Looks like some tidy work. Did you ever go with an HRV? I just had one installed last week, happy to talk about it..


sure, tell me about it. i haven't done anything to the HVAC yet. i posted another thread about moving my thermostat to the basement to help with regulating temps between upstairs and downstairs, but haven't gotten much feedback yet.


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## lml999 (Jan 19, 2017)

iron said:


> sure, tell me about it. i haven't done anything to the HVAC yet. i posted another thread about moving my thermostat to the basement to help with regulating temps between upstairs and downstairs, but haven't gotten much feedback yet.



Moving the thermostat won't change the temp balance between upstairs and downstairs. If you can change the heat delivery (opening/closing vents, etc) that's a better way to do it...or create an additional zone. In our old house we separated the basement from the main and upper zones, that was much better. In our new house, we've got one zone for the basement and two zones on each of the two other floors. Makes it much easier to dial in temps or to not heat a particular part of the house.

With regard to the HRV - find someone local who really understands HRVs. Maybe a local HVAC guy. It's not rocket science, but it does require some thought to where input/exhausts go...and the unit and ducting take a *lot* of space. The HRV itself must be located in a conditioned space...it can't be in a cold attic (has to stay 50 degrees or above). It also will need power and a place to route a condensation line. I thought our $800 Fantech could do multiple rooms/levels, turns out you have to spend several thousand dollars to get a system that will properly cycle air through multiple floors. So we ended up putting the unit in the boiler room, below our  large first floor den. Fresh air vent is at one end of the den and exhaust vent is at the other end, near the kitchen.

You also need a nearby location for the outside vents, and they need some space around them (can't go under a deck, for instance).

I would like to have provided fresh air to the master bedroom upstairs, but my HVAC guy said that input/output needs to be balanced.

Feel free to ask more questions...


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## iron (Jan 19, 2017)

lml999 said:


> Moving the thermostat won't change the temp balance between upstairs and downstairs. If you can change the heat delivery (opening/closing vents, etc) that's a better way to do it...or create an additional zone. In our old house we separated the basement from the main and upper zones, that was much better. In our new house, we've got one zone for the basement and two zones on each of the two other floors. Makes it much easier to dial in temps or to not heat a particular part of the house.



thanks for the feedback. 

given the layout of our ductwork (one main trunk from the furnace that branches all throughout the house (up and downstairs)), there's no way it could be converted to a zoned system. 

the reason i think the temp balance will change is that the downstairs currently gets no warm air directly from the fireplace. it gets no air from anywhere. if i put the thermostat in the basement and set it to 66, the furnace will kick on and start heating (up and downstairs) until the basement reaches that temp. in the process of doing that, it will be using a good amount of the really warm air from the superheated living room with the fireplace as its source. essentially, we'll circulate and mix the air in the house. 

if the thermostat stays upstairs, i can't just program it to be 74 degrees (to overcome the natural 73 degrees from the fireplace) and have it try to raise the upstairs temp to that level constantly. even then, the downstairs likely wouldn't be the temp we want.

does that make sense?


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## lml999 (Jan 19, 2017)

iron said:


> thanks for the feedback.
> 
> given the layout of our ductwork (one main trunk from the furnace that branches all throughout the house (up and downstairs)), there's no way it could be converted to a zoned system.
> 
> ...



I understand. Can you run the HVAC fan without heat on? Otherwise you're going to cook in the upstairs...


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## iron (Jan 19, 2017)

yes, i can run FAN only, but that won't allow me to set and maintain a temp. i think i will do some test runs this weekend if/when temps drop a bit.


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## maple1 (Jan 20, 2017)

You don't have any manual dampers in your ductwork anywhere? If you did, you should just be able to move your thermostat downstairs, and close up some of the dampers going to upstairs. (Assuming you have adequate ducting to the downstairs).

Thanks for the additional replies & pics also, looks like what you did is about what I was thinking of doing.


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## velvetfoot (Jan 20, 2017)

maple1 said:


> looks like what you did is about what I was thinking of doing.


So, you've got a wood boiler, 660 gal of storage, and enough wood in your basement to last the winter....must have a pretty big basement!
However, I did the same thing, with foam and sheetrock on the wall.  If you have to cover the foam with sheetrock anyway, you might as finish it.  I will say the foam was exposed for what turned out to be years though.  I never did anything with the concrete floor and ceiling though.  While most of the ceiling stuff was above the joists, there is a steel I-beam that would've have to been dealt with, unless a suspended ceiling was used, then that would've required more work around the windows, yada, yada.  Then there's the concrete floor, which still keeps things cool-any insulated covering probably wouldn't work out well when moving any of the 8 pallets of pellets down there..

I will say that once the sheetrock was up and the window and door frames extended (which wasn't that big a deal as I recall), it does look good.


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## iron (Jan 30, 2017)

iron said:


> yes, i can run FAN only, but that won't allow me to set and maintain a temp. i think i will do some test runs this weekend if/when temps drop a bit.


cross-posting:
https://www.hearth.com/talk/threads...t-for-cycling-warm-air-from-fireplace.159822/


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## jpety (Aug 22, 2018)

Hi there,

I see that you've posted this topic/question a few years ago and hopefully, based on your experience, you'll be able to give me some advice. I am also in Seattle, finishing my earthquake retrofit (structural got approved last week). The siding and windows of my house were fully redone last year and we decided to add a Low-E wrap under the cement-based siding to better insulate the house. Now that I am getting ready to insulate my basement (as per city of Seattle requirements) with R-13 EcoTouch Fiberglass, I am wondering if an extra vapor barrier (faced insulation or Visqueen covering the entire ponywall) is needed before placing the OSB/Plywood, or if it will be an issue considering I already have one on the outside of the house (at least it looks like Low-E wrap is considered a vapor barrier).

Thanks in advance.


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## iron (Aug 22, 2018)

the key is to prevent moisture on surfaces where the temperature delta occurs. cold outside air next to heated air inside. i would think that if you have pony walls in front of your plywood walls, they will simply let the heat pass through the drywall until reaching the plywood-covered walls. that's where warm meets cold and condensation would occur. i would tend to think that the plastic covering will just trap the air and make things worse. 

what i would do if doing it again and didn't have a newborn at the time:
put 1.5-2" xps on the floor. hire a closed cell spray foam contractor, and spray all your exterior walls to at least 2" thick (multiple passes). all done. might be $2k for the spraying. $1k for the floor foam.


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## jpety (Aug 22, 2018)

Thanks. That's what I'm thinking too. Ultimately, I'm not planning on finishing my basement right away, just finishing the EQ retrofit. I think I'll simply finish the work as I started and then look inside every 3 or 6 months for the next year or so to find out if it works or not. 

For floor and foundation, I'm far from being there and I also have a little one at home so we'll see.

Thanks again.


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## iron (Aug 22, 2018)

jpety said:


> Thanks. That's what I'm thinking too. Ultimately, I'm not planning on finishing my basement right away, just finishing the EQ retrofit. I think I'll simply finish the work as I started and then look inside every 3 or 6 months for the next year or so to find out if it works or not.
> 
> For floor and foundation, I'm far from being there and I also have a little one at home so we'll see.
> 
> Thanks again.


if you want me to come over and look some time, let me know. ideally you're north of the city.


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## jpety (Aug 22, 2018)

I'm in Greenwood, so yes, North of Seattle. Where are you at?


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