Q&A: A Forum for Green Building Experts and Beginners

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1 Answer
I have a roofing / deep energy retrofit question

I have a roofing / deep energy retrofit question. I'm just beginning a deep energy retrofit as a retirement home on a permaculture garden-farm project in northern Alberta, Canada (ASHRAE Zone 8). Tomorrow we are moving a 42’x28’ bungalow 200 km.

As it needs a new roof (old shingles are stripped to sheathing and house tarped at old site), the current plan is to chainsaw the eaves, then apply air/vapour barrier, insulation (either Roxul ComfortBoard or EPS) to exterior walls, preserving as much interior space as possible.

In Energy efficiency and durability | Asked By Janet Blayone | Jul 22 14
3 Answers
Using rigid insulation correctly

For zone 6, when building a new construction wall assembly, why wouldn't this method work well- starting from the exterior side- OSB sheathing, Roxul R-23 cavity insulation, 1-2" foil-faced polyiso rigid board placed continuously over inside of wall, joints taped appropriately, furring strip, drywall. It seems that this would pose the least risk-as the continuous foil-faced polyiso will stop to a great extent vapor transmission. I realize that no assembly is completely vapor leak proof, but the OSB can dry to the outside if need be.

In Energy efficiency and durability | Asked By Peter Nadler | Jul 22 14
2 Answers
Liquid Applied vs. Sheet WRB

Hello Again!

I am trying to decide on the best weather barrier to use on my house, and would like to hear some opinions on liquid applied WRBs. I am looking at Henry Air-Bloc, for example. I am inclined to think that a liquid applied weather barrier would be more effective than a housewrap like Tyvek, but can't seem to find confirmation one way or the other.

I am hoping to use this external layer as my primary air barrier, so it is critical that it be as effective as possible.

In Green products and materials | Asked By Stephen Youngquist | Jul 22 14
3 Answers
Has the Oak Ridge study on convective heat loss in blown fiberglass been updated to cover newer materials?

I'm evaluating blown cellulose vs. blown fiberglass (Knauf Ecofill). The Oak Ridge study is often quoted regarding the drop in R-value of blown fiberglass when the temperature differential is high. However the tested fiberglass density (.4 - 5 lb/ft^3) is much lower than the newer fiberglass.

In Energy efficiency and durability | Asked By Neil Weinstock | Jul 21 14
3 Answers
Evaporative Cooler vs Mini-split

I'm in the planning stages of a remodel and need to make a decision about cooling.

In Energy efficiency and durability | Asked By Eric West | Jul 21 14
1 Answer
Spray foam info

Starting a new build (1 1/2 basement walkout), all 2x6 exterior walls w/ brick veneer in GA, CZ 3. Above grade, would like to do spray foam in 2x6 walls, 1/2" or 1" of rigid foam board on the exterior, and a 1" air gap. Will this require a housewrap or can I do without the rigid foam and go with a housewrap? Also, any recommendations about insulation strategies for the finished basement. Thanks!

In General questions | Asked By David Myles | Jul 22 14
8 Answers
Spa cover

Spa covers are very expensive, and very short lived, because they are made of vinyl that tears and expanded polystyrene that absorbs water. Does anyone have any with experience or thoughts on building a spa cover? I was thinking marine plywood and EPS.

In General questions | Asked By william goodwin | Jul 21 14
11 Answers
EPS characteristics

I have a simple question about EPS that I'm sure one of you can answer for me. Outside of buildings I encounter EPS in two places where it seems to act in very different ways. I see foam anchor buoys and fish floats off our coast and washed up on the beach that seem to maintain their buoyancy and lightness or years. But those of you with hot tubs will have noticed that the foam inserts gain weight over time and within a couple of years the initially light cover can easily triple its weight.

In General questions | Asked By Malcolm Taylor | Jul 10 14
14 Answers
How to properly insulate a poured slab with PEX?

Hello,

I'm looking to pour a basement slab as follows:

6" washed 3/4" stone- compacted
2" XPS
vapor barrier

Next I'd like to tie the PEX to mesh and pour. That's the problem. Masons hate this, PEX can get cut when control joints are cut. Chairs holding up the mesh just get crushed or are a trip hazard.

If the PEX is attached to the foam, not thinking you can put the vapor barrier over the foam / PEX, plus the PEX is under 4" of concrete, and I understand it should be within the 4" of concrete.

Seems this very point is a sticking point in the overall theory.

In Green building techniques | Asked By Ted White | Feb 23 14
13 Answers
Replacing boiler and perhaps radiators in small Massachusetts colonial

I have a 2300 square foot colonial, built 1960 in Zone 5A, and I'm looking to replace the boiler with a direct-vent mod/con boiler, with indirect hot water. Goals would be increased efficiency (which isn't just about saving money), reliability, low maintenance, and retiring the current chimney flue.

In Mechanicals | Asked By Daniel Griscom | Jul 19 14
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