Finishing Basement - Insulation Question

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GreyGhost said:
Personally, I try to keep the drywall up off the floor (by feet if possible) in basements. Basements have a habit of getting wet and drywall wicks the moisture right up the wall. Using something like paneled wainscoting or beeadboard for the bottom row of sheathing isn't expensive and allows for easy replacement. No idea how code feels about this, but I have had to help fix a few basements that were destroyed by 4" of water or less and I would hate to have that happen in my house.

Another vote for vapour barrier in your system. a) I wouldn't expect 1" foam to have the dew point inside it (I expect it will be in the Roxul) b) it's not a vapour barrier

From Owens Corning:
1” FOAMULAR® sheathing actually has a vapor permeance (1.1 perm) that is higher (passes more water vapor) than the commonly accepted definition of a vapor retarder (1.0 perm), and, higher than ½” OSB (0.70 perm), commonly perceived as an acceptable sheathing. So, from that perspective alone, FOAMULAR® passes more water vapor (is less of a vapor retarder) than does commonly accepted OSB sheathing.
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So far, it looks like poly is required on the inside if the foam is less than 2"...

I also contacted the manufacturer (Foamular / Owens Cornering Canada) yesterday who simply suggested to refer to our local building codes.

EDIT: Received an email which stated -- "In most cases, Foamular can be considered a vapor barrier at 2 inch thickness, but you'll need to check your local building codes to see if it suffices as one to their standards."
 
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Slick_Steveo said:
some people do. Others are going with bluewood But whatever you use, never put bare wood directly on concrete.
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Thank you very much! I'm just not sure about putting pressure treated wood inside the house, and what happens when it gets wet inside the house, because it's treated with arsenic (not any more?) and other not-so-friendly chemicals. I'll check what kind of chemicals are used for bluewood treatment.
 
ViperZ said:
For basements, when you frame, do you use pressure treated 2x4s for the bottom of the frame or a non-treated one? Thanks!
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Even if you use bluwood, you still should have the wood off the concrete. For a couple of bucks, you can buy a roll of 3-1/2" wide foam - meant to go under base plates.
 
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New homeowner grade PT is arsenic free but still shouldn't be used indoors, I would not use it in the house except or maybe the basement wall bottom plate, still with a gasket underneath it. Bluwood is something different and is intended for in house use.

One mistake people make is leaving an air gap between the insulation and the concrete wall. This will rot out the floor joists on the first floor. In winter the bottom of the foundation wall is warm and moist, this warm air will rise and then condense on the cold end of the floor joists (near the outside wall), rot comes next. It was OKish in the past since old growth wood is more rot resistant, compared to what they build houses out of now.

For spray foam they had a good story on I think Marketplace a few weeks ago. Turns out if it is not done right (maybe too tick per coat) it can have some serious out-gassing issues. Just some food for thought on contractor selection, still likely the best choice. They also found some formaldehyde in a sample..

Personally I like the idea (since it is still 100% DIY) of closed cell foam board right against the foundation with bluwood strapping over-top for mounting the mold resistant drywall, maybe another layer of foam between the straps. Nails will not puncture the vapour barrier, materials will not (or are hard to) mold...

I am reluctant to over insulate though, my house has none in the unfinished basement at the moment and to be honest it is warm down there in winter and cool in summer--seems to me that is what I want...
 
Is tuck tape specified to adhere to foam board?
 
Baggsy said:
Is tuck tape specified to adhere to foam board?
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Not officially specified, but....

POST # 1:

tony giovinazzo from Waterloo Canada writes: Mike I am preparing to finish my basement and have read in this blog that you recommend rigid insulation with duct tape and NO vapour barrier. Can you please describe more specifically the details of the insulation you recommend and does this fasten to the foundation wall? As well, I thought that the insulation is placed betweent he studs with a vapour barrier (poly) over top - is this correct. I would really like the details on how the studs and insulation is used. Your show is great and my young daughters and try to catch it when we can. High praises to you for your support in education and ethics advocacy in skilled trades.

Mike Holmes: Hi Tony. NO, not 'duct tape'--TUCK tape. It's a totally different thing!! What I recommend to create a thermal break in basements is rigid foam insulation, with TUCK tape and no vapour barrier. The foam goes directly against the foundation walls and floor, and you stud in front of it, and lay your plywood on top of it on the floor. (1" thick foam on the floor and 2" thick foam on the walls.) Make SURE you use the correct type of adhesive-one designed for use on foam-since many adhesives will melt foam. And, use 'shiplap' foam insulation, so the edges overlap, and use adhesive on the overlap. Tuck tape all seams AND, be sure to use a spray foam in all the corners. You don't need vapour barrier, and you won't need to insulate between the studs.

POST # 2:

Lloyd Armstrog from Nepean Canada writes: Hi Mike, I am in the process of renovating the basement of my 30 year old split level bungalow. I have seen you use foamboard on the wall and then frame in front of it and insulate with Roxul batt insulation between the studs. Do you install vapour barrier over the roxul or is the foamboard (tuck taped joints) a sufficient vapour barrier. I can't get a concensus from the contractors and building suppliers I've spoken to. Can you please give me the definitive answer I've been looking for? Thanks in advance, Lloyd

Mike Holmes:Hi Lloyd. If you use the rigid foam insulation and tuck tape it, then that is your vapour barrier. You then frame your walls in front of that, insulate with batt insulation and put your drywall over that. NO additional vapour barrier-if you did, then you would be sealing the insulation in and restricting the air flow and trap moisture which will lead to problems.

POST # 3

Paul Savage from Brooklin Canada writes: Hi Mike, I have a basement question and have seen many of your shows dealing with various basement issues. I moved into a brand new home a little more a year ago and to date there are thankfully no signs of any moisture issues in the basement. I would like to soon start to do some refinishing work down there and I know that you always talk about creating a thermal barrier to prevent moisture related issues such as mold. I'd like to take the same approach you describe in your shows using rigid insulation, however the builder has already parially insulated the top four feet of the poured concrete walls (I assume to the frost line) with a fibreglass batting and moisture barrier which is nailed directly to the walls. The bottom four feet remaining bare. How do I incorporate the existing insulation into my plans of creating that thermal barrier on the walls. If possible I'd like to use the insulation that's there and 'tie-in' some rigid foam on the bottom. Is there an acceptable way of doing that while still achieving that barrier that you discuss, or is there a better option. I know I could always pull down the existing fibreglass insulation ('It's all coming down') and complete the entire job with rigid insulation, but if I could, I'd prefer to work with the existing insulation that's there. Any thoughts? Thanks Mike. Paul

Mike Holmes: Sorry Paul, you've really got to take it all down. Remove the pink insulation blanket and use rigid foam and tuck tape, no vapour barrier to create a 100% thermal break. You can't do it half-way-it won't work. Period. You may not see it, but there is trapped moisture in that batt insulation-I see it all the time. That insulation hangs to just below the frost line-it all about Minimum code requirement, which isn't enough.


http://www.theglobeandmail.com/life/home-and-garden/real-estate/the-star-of-holmes-on-homes-answers-your-questions-in-this-blog/article1107033/?page=all


If Mike says it, it has to be right.... ;)
 
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For anyone else considering the foam board - I called the City of Vaughan Building Code Department and spoke with the inspector for my area, 6mil poly is required even if you're using the foam board.

I will be installing a 1" Rigid foam board, taped along the seams (WITHOUT sealing the top and bottom with spray foam), installing either r14 roxul batts or r12 Fglass in the 2x4 frame, 6 mil poly after the batts, 1/2" drywall.

DONE.

Greatly appreciate all the input,

JoeRider
 
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JoeRider said:
For anyone else considering the foam board - I called the City of Vaughan Building Code Department and spoke with the inspector for my area, 6mil poly is required even if you're using the foam board.

I will be installing a 1" Rigid foam board, taped along the seams (WITHOUT sealing the top and bottom with spray foam), installing either r14 roxul batts or r12 Fglass in the 2x4 frame, 6 mil poly after the batts, 1/2" drywall.

DONE.

Greatly appreciate all the input,

JoeRider
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What are you going to do in the rim joist area? I think that area is more problematic than the concrete walls...
 
I have found another water leak in my basement. It's intermittent and only comes out during heavy rain and then dries up which is why I haven't noticed it before. Of course it is behind pink fibreglass batting a previous owner put up and on the side that is the neighbour's driveway. Not sure if it is from the driveway where the walls meet or somehow running down the side of the chimney or something. Frustrating.

I don't think it is much worth re-doing a basement unless you can really be sure it is dry. Doing a cheap job of it just wastes money and will require it being redone properly in some manner.

So many things about my place are screwed up. Good example is a previous owner removed the clearout cap on the drain pipe and had the kitchen sink drain into it. Of course they didn't put a wye into it so no more clearout except for the floor one which is for the street portion.
 
I used spray foam (tiger foam) in the rim joists two weeks ago. I did three passes and still have 1/4 left in the tank.
 
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