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14 Answers

GBA blog dated 2015: "How to Insulate a Foundation"

I've read many articles from various reputable sources as well as this one from GBA http://bit.ly/2lAt69b and I have a follow up question...

Martin, you've recently replied to my retrofitting basement questions regarding insulating a 1974 bungalow in climate zone 7a, so thank you.

In General questions | Asked By Todd | Feb 10 17
1 Answer

Stone veneer or XPS?

Question I am building new house and have XPS 2" on exterior on foundation wall running below grade and above grade was wondering if anyone can give me some Technique
Was thinking about using a stone veneer on the concrete that is above grade anyone that I ask says need to remove the xps from the foundation wall on exterior to attach stone veneer question is there a way to attach stone veneer leaving xps on wall Thank you

In General questions | Asked By Boris Rubinstein | Feb 14 17
4 Answers

Multi-speed inline exhaust fan

Is anyone aware of an inline exhaust fan that has multiple speeds so it can do low continuous ventilation and on-demand ventilation?


In Mechanicals | Asked By John Ranson | Feb 12 17
9 Answers

Best way to reduce interior humidity in tight house?

I have been building and refining my "best practice" for 20+ years. I have built a house with walls wrapped in XPS foam (sheetrock-->2x6 with fiberglass batt--> osb--> XPS--> rain screen--> cladding). All XPS joints are taped. The roof is TJI cathedral with blown in open cell foam under plywood, under shingles. The sheetrock finishers had turned up the heat inside to 71 degrees and the temperature dropped last night to the upper 20's. I'm building in zone 4A. There is a conventional HVAC system with fresh air intake motorized damper.

In Green building techniques | Asked By mtndrew | Feb 9 17
3 Answers

Where is the best place to go to get a building science education?

I am a young builder looking to learn more about building science. I do a lot of research on the internet but I think my time could be better spent in a classroom, virtual or otherwise.. I've looked in to yestermorrow but would like something geared more specifically to building science. I subscribe to the fine Homebuilding podcast and building science corporation. They have really opened my eyes but I would like a more formal education.

In General questions | Asked By Spencer Shemwell | Feb 12 17
4 Answers

Insulation recomendations?

Hi our new house is being built with 2x6 walls with exterior CDX plywood with Enviro Dri on the exterior. I'm debating open cell in the wall cavities vs dense pack cellulose. Any recommendations on either for both comfort and long term pay back. Is there any other options i should consider? Thanks for your help

In GBA Pro help | Asked By Michael Carreiro | Feb 13 17
5 Answers

Building envelope and insulation for new build holiday home

I am sorry this is so long, but your expert thoughts are greatly appreciated!
- In the planning stages of a two storey holiday home with an unheated garage below and 2 bedroom with living area and small bathroom on the second floor.
- 40 x 30’ foot print, about 800sq ft for the living area. 1:12 “Flat” roof
- Climate zone 4 marine (north of Vancouver, Canada). Temperature rarely drops below about 28F and the building will be unheated and unoccupied for long periods in winter. Summers are warm but typically not humid.

In Plans Review | Asked By Quinn Sievewright | Feb 13 17
13 Answers

Insulating at the sill when joists are embedded in concrete?


I have a 70-year-old house in Ontario. The floor joists are fully embedded in a poured concrete foundation (the top of the joist is flush with the top of the foundation).

I've read several comments on GBA suggesting that I avoid putting rigid insulation between the joists because it'll make the joist ends colder and more prone to rot (if moisture is somehow getting in there). However I've read contrary statements in NRCan's "Keeping the Heat In", section 6.2.6. The diagrams there show that it's okay to put in 1" or less of rigid foam, and caulk the gaps.

Who's right?

In Green building techniques | Asked By Steve Smith | Mar 11 16
4 Answers

Fastener schedule for plywood / OSB roof sheathing over rigid foam

I am installing a new unvented cathedral ceiling in a desert. Roof is low-slope and has a structural plywood deck over 2x rafters, with 1" polyiso on top of the deck, then another layer of plywood, followed by a built-up reflective membrane roof. I cannot find any information anywhere about how many screws to use on that second layer of plywood.

The way I figure it, I have three choices:

In General questions | Asked By Ryan McCulley | Feb 13 17
1 Answer

4 Insulation questions

Greetings, I am finishing my gutted basement, and had a few insulation questions. I live in Portland, OR (zone 4).

General information:
My foundation is poured concrete, 4 feet underground with slab floor. The basement walls therefore consist of concrete (lower half), and 2x6 stud wall (upper half). Stud walls have exterior sheathing, house wrap, hardiboard siding. On the interior, there will be 1/2 inch plywood (earthquake retrofit) between the studs and drywall. My house was built in 1967.

Question 1:

In General questions | Asked By Matt Draper | Feb 13 17
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