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9 Answers

Crawlspace insulation

Hi everyone - Looking for some clarification around how to best re-insulate a crawlspace that has falling fiberglass batts.

The crawlspace is under an enclosed 3 season porch (no heat or AC), the crawlspace has insulated steam pipe and h/c water pipes running through it. The vents were previously covered with plywood (but not air sealed). The house also had termites, so I need to be able to continue annual termite inspections.

In Energy efficiency and durability | Asked By oldhouse7 | Feb 1 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
1 Answer

Mini-splits in a split-level home? (Zone 4)

Hi all,

Thanks to all GBA contributors for the info on this site, and to Dana Dorsett for the technical guidance on many related topics from another forum. I became a first-time homeowner last fall. Your contributions got me started in the right direction on my HVAC replacement project.

In General questions | Asked By Jerry C | Feb 13 17
3 Answers

Metal vs tile roof, with price parity?

I live in Central Europe, where, for the most part, tile roofs are by the most used roofing system.

Currently, I am trying to do some cost cutting on my future home, so I started investigating metal roofing. Looks really great.

But where I live, it's not any cheaper than tile.

House is brick, mortar and concrete, and roof itself would not be insulated, only the ceiling.

Should i keep investigating metal roofing, or just go with tile in this case?

Also, while I'm at it, is it worth giving any thought to flat roof, when low energy houses are concerned?

In General questions | Asked By davor radman | Feb 13 17
3 Answers

Open-cell spray foam for field stone basement wall?

I am finishing a basement in a old home (1850s) in NE PA. Can open cell spray foam be applied to an interior field stone basement foundation wall if the wall has had a vapor barrier such and Grace ice and water shield attached to it? I ask because open cell for one is much cheaper than closed cell and does not have the off gassing and harmful blowing agents that closed cell does. Closed cell however is vapor permeable. I must put in the grace shield due to the small amount of moisture that does weep from two of the foundation walls.

In General questions | Asked By Ben Hardy | Feb 10 17
4 Answers

Insulating diagonal hardwood sheathing in climate zone 3 - insulated lap siding + drainwrap?

My wife and I are completely renovating my great grandparents' house in central Mississippi, and we will soon replace the siding, much of which is in bad condition. As we have looked at options, the insulated Hardie lap siding has been one recommendation, with the idea being that Tyvek drain wrap would go between the back of the siding and the beautiful diagonal sheathing.

In GBA Pro help | Asked By Joel Fyke | Feb 12 17
3 Answers

Kneewall insulation planning stage - Thoughts appreciated

Hi All,

I have read all the available articles and Q&A on kneewall insulation, including Dana's comments on playing the fool on multiple occasions and therefore would appreciate your views on my situation / questions / possible approach.


- Climate Zone 5 (Chicago area)
- Walk-in closet over attached 2-car garage (20ft x 8ft space)
- Garage attic has soffit and ridge venting and this attic is isolated from the rest of the home's attic space, except for one HVAC duct which comes from the "main" attic. This duct runs above approximately half of the kneewall ceiling

In Energy efficiency and durability | Asked By Joe Duchek | Feb 10 17
1 Answer

Balloon Frame Basement Air Sealing and Insulation


I have a 1906 balloon-frame house in Essex County, NJ (Zone 4A, borders 5A). My unfinished basement is quite cold, which makes first floor cold as well.

In Green building techniques | Asked By Robert Howell | Feb 11 17
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