Home Exterior Insulation Options.

[rabbidrabbit]

OK,

The area is 35 X 30 which includes the living room, dining room area and kitchen/pantry.

The ceiling is being trussed up to get rid of interior load bearing walls and all of the floors need to be refinished.  I'm going with red oak unless I hear better ideas.  

For the ceiling, I was intending to use R38 fiberglass bats and the outer walls that are being built will be 2X6 although thats not much considering there is just 6ft on the side and the 30 ft exterior wall that is the living room and dining room being pushed out is comprised of a 12ft slider, 8 ft picture window and french doors.  What matters from the insulation point is the ceiling and floor.  The 6 ft by 30 ft area being created by pushing that wall out is currently a cement floored porch.  there is about 3 inches of floor depth which needs insulation but I'm not sure what.

Ya, it's a brain full...>  Any good ideas?  how do I figure out the value of the insulation?  1 sq ft of R38 bat buys me what energy savings over just drywall in the ceiling?  If I add a radiant barrier does that take off so much per square ft?  Whats my best bang for the buck in the insulation world and what kind of payback does it entail?

[eskimo2]

Originally posted by Lizking
BTW, if you are comfortable applying the siding, there is no reason not to insulate it yourself.

That's my plan.  There's almost nothing on a house I won't do.

[Lizking]

Sorry, long day at work.  What kind of support are you adding to  the rafter plate column-wise under the trusses?

A simple way to look at insulation is to break it into 3 types:

The First is Radiant heat shielding.  Simply put, any film that reflects a large portion of heat energy directed at it.  It is not critical that it be a perfect fit, like the moisture proofing should be.

The Second is "dead air" space.  This is, at it's most basic, how insulation of most  types work.  Air is an excellent insulator, provided it is not allowed to mix freely.  Foams work well because of the multiplicity of surface area involved.  Things like the white styrofoam are good, but they are open-celled, that is, they allow air transfer.  The wallboard foams are closed cell, and the more expensive it is, the smaller are the bubbles, and thus the insulating value.  

The third is thermal mass, which has no application here.

I can't give you any calculations without climate and existing structure data, but it is usually substantial, in the 30% range.

If I were going to build a stick house, my wall makeup would be (Central Texas climate):

From the inside, out:

Doubled 3/8" ****rock-2x6 stud w/batts-OSB-Tyvek-furred 3/4" foiled blue board-1x6 shiplap siding.  Properly flashed and weeped, of course.

Ceiling vs wall insulation depends upon your climate data as well.