# Basement Insulation



## jlmilligan (Jul 22, 2008)

I am considering insulating my basement. Just wondering if anyone has any other ideas or input on payback. Here are the details: basement is 1536 square feet with radiant heat in the slab. I currently keep the basement temp at 62 degrees. One 28 foot section is stick framed and the rest is 8" concrete wall aprox. 8 feet tall. I was thinking I will put up 2" styrofoam T&G;panels held in place with 1" x 3" strapping. I figured it will cost around $450 to $500 bucks. What are your opinions on sealing the walls first? They were sealed with the black tar from the outside before it was backfilled and my basement has always been dry.
Thanks for the input.


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## Dix (Jul 22, 2008)

What's the temperature, when the weather is at it's worst, if you don't have the heat on?


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## iceman (Jul 23, 2008)

if you have a stove down there do it.... if you heat it with oil do it
if you wanna save money use regular insulation and just compress it .... you won't get the r value as advertised but will be at least eq to 2in styrofoam but a lot cheaper .....and run a humidifer you'll be surprised


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## velvetfoot (Jul 23, 2008)

I've been thinking about doing this too, though I have no radiant heat.
Sheetrock covering is required, I've read.  Then you'd route the electric wires in the space created by the T&G;strapping?
Radon is a problem around here and something to think about, as in sealing cracks and coating the walls, etc, if only for resale.
I am able to control the radon with a pump sucking air through a pvc pipe through the floor slab, and my basement is also dry, knock on wood, so I don't think I would coat anything.

It won't be as cool down there in the summer though, will it (if that is a factor)?  You would think it would stay drier since not as much condensation.
Thing is, I already have an insulated basement ceiling, so that would kind of create an independent insulated space, which I don't know if good or bad.


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## velvetfoot (Jul 23, 2008)

In my last place we had foil batts in the basement, that didn't require covering.
It always stinky down there in the summer though, and I blamed moisture condensing in the fiberglass which was against the concrete.
I figure styrofoam should support mold and maybe the paperless drywall as covering wouldn't either.
The sheetrock covering would be a hassle though, just for fire proofing.


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## ms440 (Jul 23, 2008)

After your ceiling the basement is the second most important area of your home to insulate assuming that your floor is not insulated.  One inch of solid foam will give you r5 which equates to a 70% decrease in heat loss for your basement. You can not affor NOT to if you are heating your slab.  2 inches is better than 1.  Another options is to use 1 inch foam and then stud a wall in front of it and insulate with UNFACED insulation and then sheetrock.  You do not want any vapor barriers in your basement wall system. Period. One half of the year vapor wants in, one half of the year it wants out. Good luck.


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## WILDSOURDOUGH (Jul 23, 2008)

Your plan sounds good to me. I just finished building- have ICF foundation w/ raident in slab- which is kinda the same principal- 'styro on concrete'.
Finished bath and man-cave with T&G;pine attached to strapping attached to plastic 'studs' built into styro.
Only problem I have with water is blowing in through walkout french doors when it rains from the west- so basement is dry and don't have to use a dehumitifier.
Insulation is always a good investment.


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## jlmilligan (Jul 23, 2008)

Thanks for all the replies. I have never left the heat off to know what the temp would be without. I would assume in the low 50's or lower. I live near Bangor Maine and it does get pretty cold here. The ceiling of the basement is insulated because I have radiant heat on the first floor too.  I would prefer not to stud up a wall because it would eat up precious space. (no garage so all storage is in basement) One thing I dont understand is that T&G;pine is ok for a wall covering rather than sheetrock. That doesn't seem any more fire resistant then foam. Anyone with experience with gorilla glue. I have heard of people attaching the foam to the wall will it and was wondering how well it holds. So far the foam still seems like a good idea. 
Thanks


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## velvetfoot (Jul 23, 2008)

I don't know about that glue, but it has to be compatible with the styrofoam.
I think that those spray insulation foams are, and it sure is sticky.
The problem is, you still have to cover it with something.
It'd be interesting if you could just glue everything, but I've read that's not considered good enough., so you'd need the studs for the sheetrock.
Maybe that planking is good enough for a fire barrier, I have no idea, but if the inspector okayed it, it must be okay.


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## jlmilligan (Jul 23, 2008)

my basement is split into 3 rooms. Boiler / oil / well room, storage / workshop room, and the rec room. I was hoping only the boiler room would need a wall covering but I couldnt get a straight answer. In the rec room, I would like to do v match pine mainly because I HATE mudding sheetrock. He did say that that would be fine. I would be happy just glueing some panels up and leaving it that way in the workshop area. It would cut installation time down. I will pass on any info I can get. Thanks


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## begreen (Jul 23, 2008)

jlm, check out this site. www.buildingscience.com . It has lots of really good information on how to insulate basements, etc.

Here's a starter for basements:
http://www.buildingscience.com/documents/reports/rr-0202-basement-insulation-systems


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## iceman (Jul 23, 2008)

[quote author="ms360" date="1216788689"]After your ceiling the basement is the second most important area of your home to insulate assuming that your floor is not insulated.  One inch of solid foam will give you r5 which equates to a 70% decrease in heat loss for your basement. You can not affor NOT to if you are heating your slab.  2 inches is better than 1.  Another options is to use 1 inch foam and then stud a wall in front of it and insulate with UNFACED insulation and then sheetrock.  You do not want any vapor barriers in your basement wall system. Period. One half of the year vapor wants in, one half of the year it wants out. Good luck.[/quote



no vapor barrier...uhuh mine has it what do i do now


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## velvetfoot (Aug 6, 2008)

Reviving this thread.
I'm finally getting around to doing something, but darn, stuff is expensive.
What can be used to glue the foam board (Dow Corning Foamular XPS) to the concrete wall, prior to attaching the furring strips?
Also, the glue could attach foam pieces to each other for sealing.
I was going to try the Great Stuff brand foam as a glue, but was wondering if anyone had actual experience.
Thanks.


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## Highbeam (Aug 6, 2008)

My buddy is attaching the XPS board to his stem walls right now with liquid nails. The tube label actually lists XPS foam as a suitable application. It was a treasure hunt for him since some off brands of construction adhesive were not suitable for the XPS. 

In two days I will be helping him pour the slab over the top of all of the foam and radiant tubing for his floor under the entire home. I'm pretty excited to see all the pipes set up.


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## velvetfoot (Aug 6, 2008)

Thanks.  Dow says anything not containing petroleum for its foam insulation.


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## velvetfoot (Aug 7, 2008)

I just got a few 2 inch panels from HD.
I saw some glues made for foam.
Also, saw that polyurethane glue, which can be bought in big tubes for a caulk gun, will work.
In fact, polyurethane is probably the Cadillac of glues, and like a Cadillac, is not cheap.
Maybe glue isn't even that necessary, with the furring strips holding it on.  However, maybe it is needed to prevent air from getting behind the foam onto the concrete.


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## precaud (Aug 7, 2008)

Both HD and Lowes sells PL, and they make PL300 Foamboard adhesive. I used it with the Dow blueboard and it works great. Inexpensive, too.


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## velvetfoot (Aug 7, 2008)

Thanks much.


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## velvetfoot (Aug 7, 2008)

I forgot to ask if and how you braced the board to the concrete or did you fasten it down mechanically right away?


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## precaud (Aug 7, 2008)

The Dow blueboard is tongue and groove. I cut it for a snug fit top-to-bottom, so I only glued a couple spots of each sheet to the wall, and then glued along the entire edge of each one. I put up all the foam board first and then put in the furring strips. Have yet to sheetrock over it...


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## velvetfoot (Aug 7, 2008)

Thanks very much again.


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## precaud (Aug 7, 2008)

Good luck with your project - you'll be glad you did it!


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## Highbeam (Aug 7, 2008)

I couldn't find the BIG tubes of PL300, only the dainty ones. If that matters to you.


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## velvetfoot (Aug 7, 2008)

HD had some big tubes of the polyurethane.


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## sinnian (Aug 7, 2008)

THE most important place to insulate is the sill plate, however to do it correctly (i.e. no air leaks) is to use the spray foam, and for the amount of space it is cost prohibitive for the homeowner to use cans.  It is best done by a professional.  There is so much air infiltration and loss through your sill plates that it is actually more important to insulate that area before even adding any to your attic.


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## velvetfoot (Aug 9, 2008)

Well, I got some furring strips to go along with the 10 Foamular tongue in groove 2" boards.
Found a big tube of the pl300.  Also, harder to find were 4" tap cons which I figure is the size I need.
I'm still not clear on how to glue/seal the foam to the wall as well as seal to each other.
The www.buildingscience.com website is not that clear.
Would there be a bead all around the edges of each piece of foam to glue and seal to the concrete, plus some in the field?
Then also some glue on the tongue in grove section for sealing?
That's a lot of glue.....


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## precaud (Aug 9, 2008)

Don't over-think it; the glue just keeps the boards in place until you get the furring strips in. Then if you want, you can seal along the perimeter to kill any chance of air currents setting up. But I think even that is a pretty subtle detail compared to the benefits of just getting the insulation up.


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## velvetfoot (Aug 9, 2008)

Thanks.  They're pretty seal crazy on that website, but the Dow site (Corning has nothing specific) just seems to say to slap it up there with furring strips.


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## begreen (Aug 9, 2008)

I agree with precaud. In our (tall) crawlspace I just used Liquid Nails LNP-901 heavy duty glue (approved for foamboard). Bought a case of the large tubes at HD and put a generous amount on each sheet. (I think we got about 2.5 - 4x8 sheets per large tube). Let it fire off for a minute, then pressed in place. Wedged a couple 2x4 T sticks to hold it for about 5 minutes while we got the next one prepped. That's all, no tap cons, no furring strips. It's been up for 3 years now and is very solid. That stuff is not coming down. 

Does it work? The coldest temp we've seen in the crawlspace was 60, with it 20 degrees outside. Normally in winter it sits at about 63 degrees.


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## velvetfoot (Aug 9, 2008)

Yeah, I don't want to overthink it.  But, it's not that clear to me how to brace it when applied on the interior.  I'm thinking I'll use the furring strips - don't know about the time factor.  Again, not overthinking: key.


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## precaud (Aug 9, 2008)

Sorry, I didn't mean that in the derogatory sense. Maybe another way to put it is: if you're going to put up drywall or another finish layer over it, then you need the furring strips. Otherwise, perhaps not, and BG's method would work fine.


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## begreen (Aug 9, 2008)

My suggestion is not for a finished space. If you are putting up drywall then put up the firring strips or 2x3s first. What surprised me was how quickly the glue fired off and started holding. All you need is a very temporary solution. Once it's bonded to the concrete, you have to chisel it off. It cures fully in about a week, but is holding well after about 5-10 minutes. The trick is to let it dry for one minute before putting it up.


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## velvetfoot (Aug 10, 2008)

I didn't take it in any bad way.  On the one hand I don't want to go totally crazy thinking about it, but I thought I might have had to rethink my whole approach since two big home stores in my area, including HD, did not have long enough tap cons for my plan.  It's good as well to have a feel for how quick the adhesive sets.


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## velvetfoot (Aug 14, 2008)

Well, I started.  I started to put up some panels, putting spots of adhesive on the back.  It's only temporary anyway, until the furring strips go up.  I smeared some adhesive to act as a sealant between an 8 inch section I had to add to the bottom of each panel.  I started smearing it on the front of the vertical tongue and groove areas, but stopped after a while because it was messy-that pl300 adhesive doesn't disnpense that smoothly.  The concrete wall, which might look smooth from a distance, is far from it.  Things I've noticed so far:

-There are a fair amount of things next to the wall that don't move that easily, like the oil tank, boiler pumps and manifold, circuit breaker panel, domestic hot water tank, sewer pipe, etc., that chances are won't get insulated.
-I'm don't know what to do about the insulation around the window and door.  Extend the frame somehow?  Flashing?  
-It cuts nice with a table saw-especially those 8" sections
-A long utility knife worked pretty good for the window opening, but not as smooth as the table saw.
-It will be tedious to remove the existing wire located on furring strips on the concrete walls to the furring strips that will brace  the inulation boards
-Then there will be the external electrical boxes that will have to be replaced with low profile models.
Anyway, a lot of liitle things and places where it looks like it'll be hard if not impossible to install the boards and drywall.
Just some obsevations so far...


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## wg_bent (Aug 28, 2008)

I did this type of renovation a couple years ago and it was very worthwhile.  I used 2" foam (blue or pink not the foil faced as that will wick moisture) then a stud wall with non-faced fiberglass.  This is what buildingscience site recommended, and it's working really well.  I sealed the cinderblocks first with drylock, glued the foam to it then did the stud wall. I finished off with sheetrock.  

Warren


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## velvetfoot (Aug 28, 2008)

Thanks.  I'm going to see how the furring strips work.
Next questions are lighting (I'm not a big fan of the recessed pots) and floor.


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## Telco (Aug 28, 2008)

I'm no big fan of the recessed pots either, but... my kitchen has them, and I've got regular 15W curly-Q CFLs in them.  With four of the six on (I keep two screwed in halfway) the kitchen is lit about as well as the six incandescent spotlights that came with the house, with none of the heat.  Just having the incandescents on were enough to heat the kitchen without the heater.  The CFL spotlight bulbs don't work well, and they take time to warm up when they are cold.  When cold they put out little light, takes about 5 minutes to warm up.  This was only nice at 5AM going to turn on the coffee pot, but otherwise would have to turn on the lights, then come back 5 minutes later if I needed in the kitchen.  This is not a problem with the curly-Q ones, they light up instantly.

I'm really hoping that by the time I'm actually building the house, that LED technology will be viable for whole-house lighting instead of spotlighting like it is now.

Also, stay away from ceiling fans with light kits that point the bulbs straight up.  They have a strobing effect when the fan is on.


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## velvetfoot (Aug 28, 2008)

I got a couple of led mini spots, mostly for the little woman who like to keep them on.  They really don't put out that much light and were, like, 25 bucks each.
I'm okay with the cf spots in the kitchen, though they do take a while to warm up.  I just don't think that the recessed lights in general put out much light.  I'm not planning on putting in more light circuits so I'm going to stick with 6 flourescent fixtures in the 1000 ft2 basement, win or lose I guess.


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## mbcijim (Aug 28, 2008)

We are getting off the topic here...

But for our business I ordered 2 LED exterior broadcast lights.  They are 50W in lieu of 400W.  We have them on 60-80 hours a week.  They are an extra $100 ($250 instead of $150), but by my math I paid the extra $100 for them in 42 weeks at $.10/KW.  They were new lights, I needed them and didn't have them before, otherwise you need to do the full $250 cost on the payback allowance.  Even throwing in $60 for install on a replacement job, that still pays for itself in 130 weeks.


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## Telco (Aug 29, 2008)

Velvetfoot, if you have a curly bulb, stick one in the pot and I think you'll be surprised at how well it works.  I was, tried it when a bulb burned out and all I had left was the curly bulb.  Was just going to be temporary until I could get another spot, but when I saw how well it worked I just replaced all of them with the curly bulbs.  And, found I only needed 3 of the 6, when with the CF spots I needed all 6.  Currently have 4 running though.

mbcijim is correct though, to go further on this we should probably start a new thread, if anyone is interested in discussing lighting.


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## velvetfoot (Aug 29, 2008)

Thanks.  I never tried the curlies in the pots, figuring the curlies-in-spot bulb would be better.  It's way more expensive though.
I still don't think 6 will kick off enough lumens for a 1000 ft2 basement.
Of course, there's the dropped ceiling style to discuss:  I heard www.ceilinglink.com was good and cheaper than HD's, but still not cheap.
Then the floor:  1" xps + what?  I'd like an engineered wood floor on top, but not sure if that's considered an adequate fire retardant.
Everything is so expensive:  the 2x8 corning formulate 250 xps from HD was something like 13.90/sheet.
Doing math for a 1000' square floor, you get big numbers (for me) for the eng. wood floor.

This could be spun off into a basement finishing thread...


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## velvetfoot (Sep 2, 2008)

Of course, then there's the treatment around the increased depth of the doors and windows for the wall insulation, and then the floor....


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## velvetfoot (Sep 3, 2008)

Starting to look at surface mount flourescent fixtures.  I'm thinking 2 bulb T8.  The lowest temp bulb they have in HD appears to be 3500K.  The curly Qs in the house are 2700K.


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## velvetfoot (Sep 12, 2008)

Most walls covered with foam now.  
Put Tyvek tape on one wall and started to drill holes for the firring strips.
The Black and Decker hammer drill crapped out after one hole! I bought it new last year and this was all the work it had seen.  One hole in concrete!   I couldn't believe it.
I took it apart and there was a broken gear and loose parts.  What a piece of crap.
I got a Harbor Freight rotary hammer drill for 70 bucks.  We'll see how that works out.


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## d.n.f. (Sep 12, 2008)

We used to Call B+D tools Black and Decker Pecker Wrecker.
One thing you don't cheap out on is tools.  You will always regret it.

Unless they are for one use only.  Then I buy Chen-Shek tooling.


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## velvetfoot (Sep 13, 2008)

I'm looking at that hammer drill now, and wow, it looks pretty substantial!  Tomorrow, I'll try to drill some holes if can figure out how it works.


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## d.n.f. (Sep 13, 2008)

You just put the drill in hammer mode (some setting) and drill.  Make sure you have the right bit for the drilling.
The hammer drill just just vibrates back and forth.
It does take a bit of force to drill depending on the size of the bit you are using.

Wear a dust mask and good luck.


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## velvetfoot (Sep 13, 2008)

I just put about 7 straps at 5 screws each.  That rotary drill is fantastic!  Goes through the concrete like butter!  I didn't realize that I needed a special bit.  Thankfully the hardware store had one: 10 bucks!  Not much force required except to hold it up in the air (not that light!).


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## egghead2004 (Oct 7, 2008)

I have a 1120 sq/ft basement and was losing heat like crazy. It took 2-3 hours of the stove running to get the warmth to come upstairs.

I insulated with the 1 inch pink poly, just glued a few sections at a time on the wall, amazing difference. Some areas I do not have the wall studs against the poly and it is stuck on there good. In fact, while looking for a water leak, I tried pulling a section off...no way. That glue is VERY srong. the p[oly broke off in tiny pieces. 

So when I finally do finish, I'm just going to put unfaced r11 in the walls. There is no problem with moisture on the walls at all when using this stuff. I used to have a musty smelling basemnt, not anymore, and my floors are still exposed. 

It is so worth it and anything more than using the correct glue is over kill when fastening the one inch. By the looks of it, it would be overkill on the two inch also.


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## velvetfoot (Oct 7, 2008)

Except for the fact that there're words all over the foam that says it has be covered with .5 " of sheetrock or equal.
Good to hear that it's not as musty even with the floor the same.


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## oconnor (Oct 15, 2008)

I am in the process of running thru the Canadian EnerGuide for Houses program.  Just insulated the Attic from 0 to R60, and replaced all of my windows.  We noticed an immediate change once we changed the two old windows in the basement - a testament to the value of basement air leakage remediation.

We are now insulating the basement walls to R23, with a spray foam applied to the sill plate, R 10 blue foam board to the walls and stud walls and fiberglass/ 1/2 drywall on top.  Total bill for the basement and spray foam under two porch/crawlspaces was around $4300

The beauty is that the program up here will rebate me up to $2000 for the R23 basement walls alone, pro rated based on percetage of coverage! In the end, I expect to get enough of a rebate to easily pay for the labor part of the insulation bills.

Any Canadians out there who haven't looked into the program, just Google the Energuide for Houses program and check it out - even includes a rebate for upgrading to an EPA wood stove, and more.


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## velvetfoot (Nov 29, 2008)

Now, I'm sure I'm not the first person to think of this, but hey I still thought of it.  

I think I might indeed put another 2" of foam over the existing strapped on 2" of foam using an idea I just had.  I figure I can:
-Rout vertical channels for the wiring in the first layer, wire stapling them in place
-Place the 2nd layer of foam sheets horizontally, routing out 1" recessed channels for the strapping below
-Cut out recesses for the electrical boxes.  Probaby screw them into concrete
-Affix the 2nd layer in place with sheets of DensArmor Plus paperless drywall screwed to the original furring strips.

I'm not that crazy about tapconning the boxes-it would be the only place where there is a metal path to the coldness

The router has good potential to do those channels (I've tested it.  A straight edge of some sorts and a couple of clamps should do it).  I don't think I can do 2" thick with the router for the electrical boxes-I wish I could.  Would there be any suggestions how to make a nice opening so a box could fit in there snugly?  The roto-zip and others are probably geared toward cutting out drywall thickness.  Maybe just a regular old drill bit:  it might go through it easily.  I'll have to try that tomorrow.

This would result in an R20+ wall that is solid, no voids.  Even with the 2' on center furring strips, I bet it will still be rugged, ie, you could run into that wall pretty hard without putting a hole in it.  I think it'll be way more rugged that putting drywall on the furring strips and have a void.  Plus there could be air currents.  (rationalizing costs here  ).  Couldn't really hang anything heavy off it though.  

Anyway, call me crazy, but I think it'll work.  Not cheap, but a thin, rugged R20 wall with virtally nothing organic and nearly no thermal bridging.

Waddya think?

Here is what I am starting with:


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## kenny chaos (Nov 29, 2008)

If it's an unheated basement, does a person still want to insulate the walls or the ceiling?


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## begreen (Nov 29, 2008)

My crawl space is unheated. I turned it into a conditioned space: insulated the walls, sill plate and the rim joist (but not the ceiling). Now it never gets below 60 down there. It makes for warmer, draft free floors and there is less duct heat loss so the heat pump has to work less.


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## kenny chaos (Nov 29, 2008)

Thanks for sharing but this is an old stone house and I'd rather not cover the walls.  Would it be wrong to insulate the ceiling?


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## velvetfoot (Nov 30, 2008)

no, it would not


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## kenny chaos (Nov 30, 2008)

But I read somewhere that the basement could get cold enough to freeze water pipes?


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