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wall cavity, need to fill?

I am building a new home in New Bern, North Carolina. It has a 1400 sq. foot "Superior Walls" basement insulated to R2.5. The vinyl will be "Cedar Max" with R-4 insulated backing. The inside walls will be closed cell 2" Poly and the roof deck will be closed cell 2.5" poly. R equivalent for these thicknesses is R-40 and R-53 respectively. Some walls are 2x4 and some are 2x6. The city inspection team says that I need to fully fill the wall cavity. That would mean using standard insulation over the poly which will already have cost almost 3 times the price of standard insulation. No one, including the inspection team, can tell me why. Does anyone have any experience with this. We are very close to decision time. Thanks, Wayne Delano

Re: wall cavity, need to fill?

when you say closed cell poly, are you talking about closed cell spray foam? or the rigid foam boards? If you are speaking of closed cell spray foam the r-value per inch is about 7.

All we do is spray foam insulation. Give us a call and we should be able to answer some of your questions.

Re: wall cavity, need to fill?

What a shame. You go state of the art and your local inspectors can't keep up with the times. Looks like Bay Harbor may have some answers for you.

You almost can't compare R-values when dealing with spray foam insulations. Find out what code book they're using and do some of your own research. I believe the International Residential Code has insulation values specifically for spray foam.

Could it be an issue of fire? If so, perhaps they would allow you to add more fire blocking instead. You may even call on your local fire department and see if this is possibly the issue.

Good post. I hope more people will come forth with some answers. Sounds like you have a well made, well insulated house.

Best of luck

Re: wall cavity, need to fill?

I may get beaten down on this one... but what about styrofoam packing peanuts? I don't think you can get an official R-value from them, but they would fill the cavity, they would insulate somewhat, and they're fairly cheap. If you do this, though, make sure you get the (don't laugh) non-edible form. A couple of companies are now making packing peanuts out of corn, and I'd imagine that if you pit that in your walls you'd have the ants showing in droves.

(BTW - I'm going to use them on interior walls I put up where there will be no wiring or plumbing, just to dampen sound).

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