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29 Answers

Polyiso for basement

Morning all

I am about to embark on the basement insulation. I have a question about polyiso. After much reading I was so sure about putting xps 2" rigid foam against walls and rim joist.

I read the gba, several other forums and as I understand, the steps are - clean the basement walls, clean rim joist, place rigid foam, seal with great stuff, place xps with foam glue on walls, tape the seams, seal the edges with great stuff, leave a inch gap and frame with stud walls.

In Green building techniques | Asked By sr kod | Dec 20 14
1 Answer

WRB recommendations for interior fireplace surround

I am redoing a fireplace surround with synthetic stone and need to know what to use for a WRB under lath mesh and scratch coat

In Green products and materials | Asked By John Bertelsen | Jan 19 15
2 Answers

What is the best section detail for a recessed porch over an occupied space?

I am desiging a recessed porch off a second floor master bedroom. The porch/MB is above the garage.

I am looking for waterproofing and insulation details for this condition.

Thanks in advance.


In Energy efficiency and durability | Asked By ERIK MAGNUS | Jan 12 15
4 Answers

Question on cut-and-cobble rigid foam in a vaulted ceiling

Hello all,

About a year ago Martin Holladay wrote an article on GBA regarding the practice of cutting rigid foam into 14" wide sections and installing them between framing as a poor man's alternative to spray foam. Being a poor man (frugal is more accurate), I've decided to implement this in our new master bedroom (which was our old garage). We intend to vault the ceiling and removing as many of the old ceiling joists as our village will allow.

In Green building techniques | Asked By Brian Gray | Jan 18 15
0 Answers

Would you be concerned about interior Formaldehyde levels with mineral wool

I was looking at using mineral wool batt insulation between studs in a staged retrofit situation. It looks like most of the mineral wool batts available still use a formaldehyde binder.

I wasn't too worried because the home is very leaky right now and I thought that I might "dilute" out the formaldehyde over a few years before I tightened up the envelope. However, I found this article by Dr. Joe http://www.buildingscience.com/documents/insights/bsi-070-first-deal-wit...

In it he shows/states that :

In Green products and materials | Asked By MIke Truxillo | Jan 19 15
2 Answers

Insulating solid brick house

Hello! I've been reading this forum for awhile now and there's so much good information about insulating I don't know which direction to head in. I have a 1950s ranch in Michigan that is under renovation. I currently have most of the walls exposed and wanted to know the best way to go about this. It's a solid brick (like small cinderblock?) house with furring strips and 2 layers of drywall on the inside. On the outside I have furring strips with vinyl siding.

In GBA Pro help | Asked By Jeff Hogarth | Jan 9 15
2 Answers

Wall assembly (Zip R) for mixed humid

Hey Folks,

My architect has planned a 2x4 wall with Zip R 1" foam sheathing. It will likely have batt or blown insulation. I see a ton of Zip sheathing around here, but I doubt much of it is insulated. Should this assembly hold up in my climate 4A (mixed-humid). I particularly concerned about vapor permanence and drying.


In Energy efficiency and durability | Asked By C. Maglio | Jan 10 15
2 Answers

Crawl space solution - Joist rot and drying-in questions

Recently purchased a home in Connecticut with a completely unconditioned, vented crawl space.
No evidence of mold or rot, but some musty odor, and a huge drag on energy efficiency as a fair amount of forced air ductwork travels through the space and air seeps in through the rim joists and vents and stacks upwards into the conditioned space. Space has what I wold describe as a poorly poured rat slab (meaning you can see dirt in certain areas of the crawl that are untouched by the rat slab).

In Energy efficiency and durability | Asked By Chris James | Jan 16 15
5 Answers

Condensation prevention for houseboat insulation

Hi, this is a revisit of the question about trying to prevent condensation and water damage while insulating, but in this case for a marine houseboat. We are talking a 3/8" steel hull, 1" air gap, with wooden frame and "rockwool" insulation bats just under 6 inches deep, then vapor barrier, wood veneered plywood sheeting interior walls. Vessel will have hydronic radiant floor heat using grooved plywood with aluminum face for the PEX tubing, and engineered wood flooring, just under 8' deck to deck height. A 15 ft beam, and a LOA of 92 ft..

In GBA Pro help | Asked By John Shank | Jan 16 15
2 Answers

Finishing insulation on unvented sloped roof with mineral wool over polystyrene

I have an unvented, sloped roof. I cut and cobbled 5 inches of expanded polystyrene into roof rafters, and 3 inches into attic wall studs. Then placed 2-6 inches of expanded polystyrene across the rafters and studs, to create a final air barrier and address thermal bridging.

I plan to cover the expanded polystyrene with 1 or 2 layers of Comfortboard IS mineral wool. Each layer is 2 inches thick. Expanded polystyrene seems ideal except for flammability, so I want to address that with mineral wool.

In General questions | Asked By Erich Riesenberg | Jan 18 15
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