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Wall Insulation/Vapor Barrier


msmity29's Avatar
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03-28-06, 11:46 AM   #1  
Wall Insulation/Vapor Barrier

I am having a 2-story, 2600 sq ft home built in the far west burbs of Chicago and have a question concerning wall construction. From what I understand, the house walls are being constucted from exterior to interior as follows: 1) vinyl siding, 2)upgraded Menard's brand Tyvek wrap, 3)7/16" OSB, 4)2x6s with R-19 poly-vapor barrier. Does this sound sufficient? Thanks in advance for your help!

 
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Gary12's Avatar
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03-28-06, 03:14 PM   #2  
This sonds adequate for sure. However, while I don't live in Chicago, I have experienced winters there and might opt to go with the highest R-value possible (like a 21). Otherwise, sounds like all the right pieces are in place. We just did our basement in Vancouver, BC (MUCH warmer climate in the winter months), pics here: http://snipurl.com/insulatingbasement, and went with an R-14/15 for the exterior walls in the basement, which was ok. We also started using Owens Corning fibreglass insulation, but switched to Roxul brand, which we found easier to work with. Anyways, enough rambling, your should be fine. Good luck!

 
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03-31-06, 08:49 AM   #3  
How would I go about obtaining R-21? I believe the space between 2x6s won't allow any more than R-19 batts.

 
msmity29's Avatar
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04-04-06, 02:07 PM   #4  
Anyone have any ideas?

 
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04-04-06, 08:26 PM   #5  
Wall Insulation/Vapor Barrier

Look at the big picture and not the advertising.

R19 batts will give you R19 insulation between the studs. Anything with a greater Rvalue, but is compressed, will give you less that an R19 between the studs.

Depending on the stud material (steel or wood) and the stud spacing, an R19 material between the studs wil really give you between a R11 and a R16 for total the wall as a composite total.

If you need to sqeeze out some more effective real insulation, you could use some rigid extruded polystyrene that does not suffer from the "thermal short circuit" of studs since it covers them and does not suffer from the infiltration problems.

Remember - Rvalues were created as a simple, quick and easy way to measure insulation and sell insulation and not measure wall thermal performance in the real world.

If you are considering the dynamic (real) situation of a wall and include mass effects, forget about Rvalues since it takes a deeper look at what is really going on.

Dick

 
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