There is a ton of new construction going on around me. Recently I noticed that all of the houses being built were wrapped with a layed of plywood or OSB. The reason that I noticed this is because my house (1981 soft contemp) only has a 1/2″ of hard foam wrapped over the studs. Now I’m no insulation expert, but this seems to be very inefficient. If I were planning to be in this house for any length of time would it be worth it to tear off all of the siding (cedar), put up plywood or OSB, and reside? Or is this just a fatal flaw of early eighties house building to be endures for the life of the house?
By the way, does anyone know if the still make 10″ cedar siding, or is 8″ all that is made today?
Thanks,
Tim S
Replies
The plywood/OSB has more structural value than insulating value. The foam has some insulating (maybe R-2 or R-3 for 1/2" material) and almost no structural value. Is there no insulation in the stud bays, behind the drywall? If not, you could have an insulation contractor blow some in.
Cedar siding is available in all sorts of sizes. If it's not stocked at your lumberyards then you start calling around and ordering it. It would be a crime to tear it all off the house, much better to work from inside.
There is fiberglass insulation in the stud bays. But even with that, what is the R value of the plywood or OSB, just for comparison. Obviously I don't have any of the new house wrap materials either. (and don't worry, I'm not just looking for a reason to tear off the siding. I'm just curious wbout my houses construction and what I need to do during my time here.)
1/2" OSB or plywood is probably less than R-1. The rigid foam insulation sold around here is R-5 per inch. The fiberglass in your walls (2x4, right?) is probably R-11 or R-13. Tyvek and other housewraps reduce air infiltration which reduces draftiness and makes it feel warmer. Good weatherstripping on windows and doors does the same.
Making major improvements to your home's insulation would probably mean major effort and cost, things like removing the sheetrock, adding furring to the walls, and reinsulating... replacing windows... things like that. One easy thing to do in some cases is to add insulation to the attic. I recently did that for a customer, went from R-19 in the attic to R-45 with blown-in.
Like David said, the R-Value of plywood/osb is pretty much useless. It's all for the structural stability. If I remember right, wood has an R value of 1(?) per inch.
Softwoods generally are 1.25 per inch; some cedar is listed at 1.3.
There are really no cost effective upgrades to the walls here at this time. Consider an extensive airsealing program, insulating the attic to R50, insulate the basement, upgrade the heating to high eff if the system is old and could go any day.
Edited 11/27/2005 8:58 am ET by experienced