robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | reply to VioletVenom
Re: Spray Foam or Batts said by VioletVenom: You can pull those knickers out of your bum now. Instead of throwing insults why not behave in a civil manner. Your cost comparison was missing in many details. This is not just about dollars. Foam accomplishes a number of things which batts do not including more R-value in the available space as well as the vapor issue. There are others as previous posters have indicated. Just looking at the dollars per cubic foot of insulation without regard to any other factors is totally worthless! |
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 VioletVenomLets go GatorsPremium
join:2002-01-02
Gainesville, FL | If the shoe fits, wear it. When you come across as pompous, as you still are, don't act so indignant when you get called out for it. I'm sure the OP is a big boy and can read through all the comments and make an educated decision by what everybody has posted. For some people cost is a major factor. I believe others have covered those "other factors" and will continue to do so. To single out my post and claim it is "totally worthless". Well played.  |
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | reply to doechsli
said by doechsli: I think foam is the best insulator per inch but once insulated, you can't ever fish a wire again in case the need arises. It doesn't have to be one or the other. Many people spray one inch of foam and then use fiberglass. That adds R-value as well as seals the house to air infiltration while still allowing the potential of pulling new wires. However, in my experience, you don't pull wires in exterior walls. You almost always have to cut the sheetrock as there is no attic access to drill through the top plates. Worst case with a foam filled wall is you have to do some foam carving to install the new wire. Not that big of a deal. |
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 grobinetteSoutheast of disorderPremium,Mod
join:2001-01-27
Springfield, VA
kudos:1 | reply to doechsli
Whoa, settle down guys. Don't get yourselves all bent out of shape over a difference of opinion. |
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 panth1The Coyote
join:2000-12-11
Boca Raton, FL | reply to doechsli
Spray foam will give you the better R value per inch but it will cost more.
If you are worried about cabling, fur the walls out to 2x6's or 2x8's and only fill the cavities partially with spray foam. Leave a little space between the foam and drywall for future cabling. |
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| reply to doechsli
Why not use what you want and then just strap the 2x4s.
The strapping is cheap[1x3]and allows room for running wires as the strapping is applied across the 2x4s.It also allows a bit af breathing space[healthier]and also noise reduction.
Also you might want to put a plastic[6mil] vapor barrier on the outside of the insulation instead of inside.Not the norm but Mike Holmes endorses it.[from Holmes on Holmes]He endorses it because it truly is a vapor barrier for your inside as well as your choice of insulation,whereas the normal way only keeps moisture from the drywall leaving any and all insulation susceptable to leaks.
Just a thought.I have done it both ways and keep in mind that spray foam is nearly impossible to remove intirely.
One can also run some abs/pvc tube or conduit tube for future running of wires when spray foam has been applied.
Good luck!! |
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 LazManPremium
join:2003-03-26
canada | Vapor barrier placement; if one is required, is dictated by temperature - it goes to the warm side of the wall - basically, if you spend more time heating, barrier goes on the inside; if you spend more time cooling, it goes to the outside...
Holmes on Homes was filmed around Toronto, Ontario, Canada... Hence vapor barrier on the inside. |
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 alkizmo
join:2007-06-25
Pierrefonds, QC
kudos:1 | reply to doechsli
Maybe I read too fast so I missed someone suggesting the follow: XPS foam boards sealed with a little bit of spray foam. Much cheaper than spray foaming everything. |
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| reply to doechsli
You can try this trick in doing your walls:
a) measure the height of the ceiling - let's assume 96"
b) measure the height of the baseboard you'll be installing. Let's assume 5"
c) Cut the drywall to 92" tall overall
d) install the drywall snug to the ceiling (you'll be 4" shy of the floor)
e) rip a sheet of 1/2" plywood into 4" wide strips
f) screw the plywood strips to the studs below the lower end of the drywall
g) attach the baseboard to the drywall (it will overlap the drywall)
Now if you ever want easy access to ALL stud cavities, just pop the baseboard off and unscrew the plywood. |
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1 edit | reply to Draiman
said by Draiman:Another option is add a 2x2 or another 2x4 onto the existing 2x4 thus extending it to add more fiberglass insulation. Yet another option is run a ton of empty conduit in the wall before you foam. Personally I'd extended the framing with another 2x4 to give you 8" of space then fiberglass with facing towards the inside and drywall over that. Cheap, simple, and effective.
Strapping a 2x2 over the existing 2x4 is a good idea, but what I'd do is spray 2" of 2lb foam into the wall cavity first. This create a vapor barrier at the exterior wall sheathing - 2" of 2b. IS a real vapor barrier according to all tests done by manufacturers & testing labs. Then install the batt insulation over that. This gives you about R26-28 in a 6" nominal wall and he ability to easily fish wires at a later time.
Do not install a poly vapor barrier over the batt insulation in this case - there should be one and only one vapor barrier in a wall, and that is provided by the 2" of foam sprayed against the exterior sheathing.
You can read more about 'hybrid' insulation like this at www.buildingscience.com |
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1 edit | reply to LazMan
said by LazMan:Vapor barrier placement; if one is required, is dictated by temperature - it goes to the warm side of the wall - basically, if you spend more time heating, barrier goes on the inside; if you spend more time cooling, it goes to the outside...
Holmes on Homes was filmed around Toronto, Ontario, Canada... Hence vapor barrier on the inside.
It depends on where the dewpoint is inside the wall cavity, which is a function of the temperature differences inside to outside, and the type of insulation & thickness. Foam sprayed in a wall cavity up against the sheathing in sufficient thickness will change the dew point in the wall to the point where water can't condense. You then fill the remainder of the cavity with batt insulation and drywall right over the batts without a poly vapour barrier. This gives the wall assembly what it needs - the ability to 'dry' to one side - in this case the interior.
A former classmate of mine is the principal @ www.buildingscience.com You can read about insulation there. Joe is one of, if not THE leading expert on this in North America. |
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| reply to doechsli
Lots of great ideas here guys.....I appreciate it. |
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LazManPremium
join:2003-03-26
canada | reply to MaynardKrebs
Agreed, the building science methods are excellent... I was just simplifying. Vapor barrier to the warm side; whichever that may be...  |
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| reply to VioletVenom
Before you make that purchase visit the EPA website about spray polyurethane foam. If you don't know what to prepare for this could be the most expensive mistake you could ever make. Also read what the CDC has to say about it. These products placed in untrained hands could place you in the ER for pulmonary distress.
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