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69 Answers

Attic is hot after closed-cell spray foam was installed

Finished attic with 4 foot knee wall , duct located in knee wall to support 2 floor,extremely hot, BASF spray tite 2 inches with spray foam wraped around rafter in knee wall but with Sheetrock on ceiling just 2 in foam In cavity . Suggestions to handle heat issue. Richmond Virginia all attic seal very well thinking heat coming from rafters under Sheetrock. Thermal convection coming from rafters. Worked done in the winter, crawl space also done, house built 1994 colonial 2 story with garage with room above with dormer. Also in crawl space does it really need supply vent and return vent

Asked By Mark Hippchen | Jun 27 15
1 Answer

Adding insulation during re-roof: Roxul or foam? Ventilate or not?

Thanks for this great website. I looked, but didn't find an answer to my specific situation so here it is:

Asked By James Hare | Jul 13 15
4 Answers

Has anyone ever seen a span table for old ACTUAL dimension floor joists?

I'm constantly working with 80-100 year old ACTUAL dimension pine floor joists. 2x8 are actually 2x8, the 2x10s actual 2x10s.

Compared to their slimmer decendants, these beefier joists can certainly carry more weight over longer spans. The problem is, inspectors (and many structural engineers, sadly) treat these as nominal framing.

Asked By AARON LUBECK | May 26 09
4 Answers

Vapor barrier for floating cork floor

I live in Peoria, Illinois (Zone 5A). I'm installing a floating cork floor over an upstairs plywood subfloor. Nearly every website I see preaches on the importance of using a vapor barrier under floating floors, but I've also seen vehement advice against it. The planks I'm installing have a thin cork layer on the bottom, so I really shouldn't use a vapor barrier right?

Asked By Yvette Richey | Jul 9 15
7 Answers

Log walls and foil facing

Hi,

We are planing to add 3 inches of rigid foam to the outside of our 6 inch log home, giving the walls R 28, better then the R9 we get with just the pine logs. We will also have a ¾ rain screen under cedar siding. I have been reading that if you had a polyethylene vapor barrier in the house, to not use foam with aluminum-foil facing.

Asked By Thomas Gardner | Jul 3 15
3 Answers

Nebraska — unvented attic with high humidity

Last year after a severe hailstorm the attic insulation and the entire roof deck of my 1600 sqft ranch style home in Fort Calhoun, NE was replaced. With the replacement we upgraded the insulation to Open Cell Icynene spray foam on roof decking. The spray foam is at least 6-8 inches on the roof, and covers the sidewalls, soffits, and attached garage ceiling. This completely closes in the attic to the thermal envelope of the house. I've been monitoring the relative humidity levels of the house for the last year.

Asked By Nick Schuler | Jun 28 15
3 Answers

Details about drywall under tongue and groove as an air barrier

I have read often on gba about the importance of using an air barrier under tongue and groove and I may be over thinking it but it seems that 1/2" ultralight has the potential for more air leaks around nail penetrations due to occasional voids in ultralight and that 1/2" could more likely bust around nail penetrations and let air in versus 5/8" but before I wear myself out hanging 77 lb sheets I figured I should ask an expert.

Thanks,

Matt

Asked By Matthew Seabolt | Jul 1 15
1 Answer

Where to put the water barrier?

Hi,
I'm going to retrofit rigid foam over a log home in Vermont. The logs are 6 inch pine logs, that have an R value of about 9, they have a clapboard cut on the outside so the house will not appear any different with a 3 inch layer of foam insulation with a rain screen and clapboard.

My question is about where to put the tyvek, on the out side of the foam or under the foam? We are replacing all the windows and doors. It would seem to me that the tyvek belongs on the outside of the foam and over the flanges of the new windows and doors.

Asked By Thomas Gardner | Jul 2 15
2 Answers

Inground gutters

A few years back I came across an article in Finehomebuiling about inground gutters. Has anyone tried this solution to wet basements? Does it work?

Asked By Daniel Cimaglio | Jul 1 15
6 Answers

Trapped moisture on SIP roof

I knew SIPs were the Achilles heel of my 100% engineered house design, But because of inattention to detail, heavy rains at a critical time of my house build pushed water underneath the PVC membrane (applied on mechanically fastened DensDeck) onto my SIP. It happened the night before the adjacent wall could be spray foamed to properly seal off the membrane. Unfortunately, the spraying was later done to the walls and the underside of the SIPs without knowing there was water present.

Asked By Edward Mallett | Jun 29 15
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