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6 Answers

Siga Corvum tape

hi all, i would like to trim the foam and apply corvum for additional airtightness. i got a little overzealous when flashing the window r.o.. should i cut the tyvek back to the same depth as the window so that the corvum would adhere directly to the window and osb? i realize if i do not cut the tyvek back i will be relying on the bond of the tyvek tape bonding the tyvek to the osb...

In General questions | Asked By erik olofsson | Mar 10 13
3 Answers

New approach to furnace sizing?

Here is something i just heard about, i wondered the expert's opinions, the page is gone so the internet archive version is linked


In Energy efficiency and durability | Asked By Alan B | Nov 7 15
38 Answers

Why is there condensation on the return ducts and mold in the attic as well 60% humidity throughout the home?

This home has since been remodeled, including all new metal duct work and insulation. The issue that we need to resolve is the high humidity in the house at about 60-65% even though the unit is running efficiently. There is quite a bit of condensation on the return ducts in the attic as well. We have had two reputable Heating and Cooling Contractors come to assess the situation to no avail. The owner attempted to contact the original Mechanical contractor, but has not been able to speak to anyone yet.

In GBA Pro help | Asked By Jimmy Miller | Sep 1 15
3 Answers

Best insulation for half-below / half-above finished basement?

hi all,

i've been reading through blogs and articles on this site and beyond (http://www.greenbuildingadvisor.com/blogs/dept/musings/how-insulate-base...), etc.

i have a basement that we are finishing for bedrooms and bathrooms. one wall is attached to our neighbor, 2 walls are 3 feet in-ground, and 1 wall opens at grade. we are installing an interior french drain, with which we planned to include a vertical vapor barrier to a 3' height (to grade).

In Energy efficiency and durability | Asked By Josh Millis | Nov 6 15
3 Answers

Insulating skylight frame

So we got our shingles replaced and took the opportunity to do a chainsaw retrofit and added 2 layers of 2" EPS with Neopor (Terrafoam Platinum) which we tied in to the existing 2" EPS on the exterior of the wall sheathing I installed two years ago. Also replaced was the enormous plexiglass dome skylight in our upstairs ensuite bathroom. I didn't think how we were going to insulate it at the time of installation however and am just trying to figure that out now.

In General questions | Asked By Zac McCormick | Nov 7 15
6 Answers

What to do with mineral wool excess insulation?

Hello all,

I special ordered a bunch of Owens Corning mineral wool insulation that is 16" x 47" x 7". I would say it is exactly the same as Roxull, however I am not for sure. I used it in my walls and now I have about 80 pieces of 16 inch wide x 47 inches tall by 7 inches thick left over. I also have probably 150 pieces from my wall studs that are 1.5" thick shavings. I was originally going to fur out my walls 1.5 inches so the 7 inch thick piece of insulation would fit right in. However things changed and I did not end up doing that, the result is a bunch of leftover shavings.

In Green products and materials | Asked By Nicholas C | Nov 7 15
7 Answers

Cutting really thick EPS foam

I have a job coming up where there is going to be 8" of foam under slab.
The foam will be glued at the joints.
Over the years I have cut foam a number of different ways with varying levels of success.

I have used Tajima knives, circular saw, sawzall, handsaw, sharpened putty knives, table saw.

All of them worked ok, none great.

In Green building techniques | Asked By Colin Lindberg | Oct 28 15
8 Answers

Foam over wall sheathing: Typar under foam?

Hi all,

We are doing 2 inches of rigid foam on top of (i.e., outside of) our wall sheathing (with fiberglass in between the studs). The lumberyard specified Typar between the sheathing and the foam, but the builder is suspicious of having two vapor barriers next to each other, and is concerned about moisture being trapped and eventually compromising the sheathing.

What is correct here? Do we use the Typar, or skip it? If we skip it, do we tape the seams of the foam?

Thank you very much for your help!

In General questions | Asked By Chris Conti | Nov 6 15
10 Answers

Considering minisplits in a dome home

Considering mini-splits in a dome home.

35 foot diameter and 22 feet tall with full livable basement, floor insulated and walls.

1370 sq. ft in basement with 9 ft. walls and 1370 sq ft on first floor, with half of a loft area of 450 sq. ft.

Cubic feet of basement is...

I have three extensions on dome: one four ft to the south 14 ft. wide, one on east 13 ft by 14 ft wide, and one to the west 14 ft wide 12 ft.

In General questions | Asked By William Leuthardt | Sep 8 15
9 Answers

Is spray-foam worth the $23k extra cost?

Our new home is currently under construction in Toronto, Canada. I'm doing my best to take advantage of this opportunity to create energy efficiency where at all possible. We will have solar panels and hope to get a Tesla Powerwall when available.

However, in regards to insulation I'm unsure how to proceed:

In Energy efficiency and durability | Asked By bob banderson | Nov 6 15
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