# Basement Wall Foam Board Idea



## velvetfoot (Jan 23, 2009)

I've been really slowly insulating the rim joist area but thought I'd post a picture or two here on my basement wall idea, and put future updates here.

I first strapped 2" of foam to the wall using 1x3's.  
My idea to put another layer of foam was to mill grooves in more 2" foam boards.
I am using a router with a guide on it.  A little slow, but could be worse.
I've tacked some in place using a hot glue gun.
I'll put Densarmor drywall over it.


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## ihookem (Jan 25, 2009)

I did this in December and it helped a little bit. I figure you will warm your basement up about 3 degrees.


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## kenny chaos (Jan 25, 2009)

ihookem said:
			
		

> I did this in December and it helped a little bit. I figure you will warm your basement up about 3 degrees.




How the heck can you figure he'll warm his basement 3 degrees by looking at a picture?


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## Wet1 (Jan 26, 2009)

You have a lot more time & patients than I do... looks good though!


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## j00fek (Jan 26, 2009)

i have almost the same thing going in this spring, im only putting 2in foam over the part of the foundation that is above grade and going to seal the joists while im there.


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## kenny chaos (Jan 26, 2009)

j00fek said:
			
		

> i have almost the same thing going in this spring, im only putting 2in foam over the part of the foundation that is above grade and going to seal the joists while im there.




The frost line here is down about 30" so I'm thinking I'll use 4x8 sheets turned the long way.


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## velvetfoot (Jan 26, 2009)

The tough parts will be the stuff next to the wall, like well pump tank, furnace (don't want to get too close to that, for sure), breaker panel, the occasional panel.  There'll be some spots I just won't be able to do.


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## velvetfoot (Jan 26, 2009)

> area above foam, between joists & sill is critical!



You can't see it in the pic, but there are four thicknesses of 2" foam starting from the rim joist.  It meets the foam on the wall.
That is what I am doing now.  What a slow process.  Spray in foam would have been easier, but more costly I imagine.


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## j00fek (Jan 26, 2009)

kenny chaos said:
			
		

> j00fek said:
> 
> 
> 
> ...



exactly what ill be doing,  i have 12 4x8 sheets now ill have to grab more i bet. 

ill be using the spray foam above this and in between the sill and floor once it gets warmer! (getting a tank system that looks like propane tanks)


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## velvetfoot (Jan 26, 2009)

You said rim joist area was critical.  I said I addressed that.  What is your point?


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## oconnor (Jan 26, 2009)

I did mine this summer, and got good results as far as heat goes, but the air sealing is very difficult.  We used spray foam in the joist cavities, but still have air infiltration from bewhen we ran the blower tests.

Here is why I think we still have leakage- we ran the foam board as high as possible, and this covered the joint where the mud sill touches the concrete foundation wall, and then we sprayed foam into the cavity.  When we ran the blower tests, air was being pulled behind the walls and out the bottom plate of the wall, where we could not get a perfect seal due to uneven floor.  I suspect the air is being pulled beneath the mud sill, which did not get sealed by the foam.  I would recommend not installing the foam board all the way up - cut it off an inch or so below the first possible air leakage point, then use spray foam to seal the entire joist space and the mud sill/foundation joint.

My 2 cents


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## velvetfoot (Jan 26, 2009)

> air infiltration
> BUT LEMME THINX=
> if vapor in warm air can only migrate thru the pores of the joists, might that result in accelerated decay? have fun.



Thanks for your contributions to the thread.


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## gpcollen1 (Jan 26, 2009)

velvetfoot said:
			
		

> > air infiltration
> > BUT LEMME THINX=
> > if vapor in warm air can only migrate thru the pores of the joists, might that result in accelerated decay? have fun.
> 
> ...




I think the moisture concerns are valid - does that foam allow moisture through.  I don't have any links to support but i do no that some of the foam board is designed to let moisture through.


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## velvetfoot (Mar 13, 2009)

Now that I finished the rim joist area I can get back to this.
Instead of using the router to make the wide slot, I am going to try a wobble dado blade on the table saw.
They are cheap, but I made the mistake of buying one at HD that didn't fit the arbor length (anybody want to buy it - unused - had to tear up the packaging to open it up).
I ordered another one made to fit the smaller arbor length, 1 3/8.


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## velvetfoot (Apr 2, 2009)

Here is a pic of part of a wall.
The routing of the groove to fit the furring strip is a little tedious, but the dado works ok.
The electrical also is a little tedious but not too bad.

Other stuff to do outside now though.


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## d.n.f. (Apr 3, 2009)

So how you putting drywall over that?  Just asking because I am pondering the same setup but was going to do the furrings for attachment points.

Ok I looked back and some furrings (sp?) on previous photos.  I need a coffee.


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## velvetfoot (Apr 3, 2009)

Here's hoping the drywall looks okay.
It'll be a solid wall;  you could bounce off it and not break the drywall I bet.


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## velvetfoot (Apr 4, 2009)

I don't think I mentioned it, but I used polyurethane Gorilla Glue to glue the foam sheets together.
I hold the top layer on til the glue cures with wood strips screwed into the furring strips.


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## begreen (Apr 4, 2009)

Looks like an excellent job. You're going to be way more comfortable next winter.


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## velvetfoot (Aug 15, 2012)

Well, I finally hung my first sheet of drywall tonight, lol.
It will be a solid wall, I believe.


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## woodgeek (Aug 16, 2012)

Anyone else doing something similar might use XPS boards already prepped for 1x3s:

http://www.homedepot.com/webapp/wcs...&productId=100320293&R=100320293#.UCzq70QtM7A

Overall, looks like a great job...XPS (pink closed cell) is the right material, low thermal bridging by the 1x3s.

Timeline looks comprable to my DIY projects 

I'm gearing up to do something similar and was planning on taping the joints with red housewrap tape. Opinions?


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## velvetfoot (Aug 16, 2012)

I'm not sure if I said it, but I taped the first layer of 2" foam with Tyvek tape, as found in the HD.  I figured that was good enough, and that the second foam layer didn't need any more.


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## daveswoodhauler (Aug 16, 2012)

velvetfoot said:


> I'm not sure if I said it, but I taped the first layer of 2" foam with Tyvek tape, as found in the HD. I figured that was good enough, and that the second foam layer didn't need any more.


 Did the same on my basement walls....the tyvek tape works well.
Using in IR Gun in the winter, there was about a 6-8 degree temp difference on the insulated wall vs the bare concrete. (Room was not heated)
You should notice some good results this winter....lookd good


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## velvetfoot (Aug 16, 2012)

This winter?  My previous post was from 2009, lol.  But yes, it's been warmer down there in the winter and less stinky in the summer.


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## Seasoned Oak (Aug 20, 2012)

I want to do this but my walls get wet after heavy rains,so im dealing with that first.


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## velvetfoot (Aug 20, 2012)

I hung a few more.  I tried to use the RotoZip and failed; bit broke and kicked up a lot of dust - set off smoke detector.  Admittedly I didn't practice, but everything I've tried to do with the RotoZip I've failed at.  Now, I've been just measuring, carefully, and cutting with a hand saw.

Yeah, you have to take care of the dampness on the walls first.


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## Wood Duck (Aug 24, 2012)

kenny chaos said:


> The frost line here is down about 30" so I'm thinking I'll use 4x8 sheets turned the long way.


 
Are you only insulating the part above grade plus the part above the frost line? Why not insulate the whole wall? You can still lose heat into cool earth that lies below the frost line.

I hope to start insulating my basement this fall.


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## velvetfoot (Aug 24, 2012)

It makes a difference, for sure.


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