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1 Answer

Fastening foil-faced polyiso under floor joists

Martin advised, "My favorite specifications for exposed floors like yours: Install a continuous layer of rigid foam on the underside of the joists -- foil-faced polyiso is the easiest type of foam to tape -- and blow cellulose between the joists." (http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-an...)

In General questions | Asked By Mark Walker | Jun 21 17
4 Answers

Basement slab insulation

Building a cabin in Montana (climate zone 6) which will have an unfinished "basement" functioning as a mechanical room containing electrical panel, water cistern, pump, pressure tank, storage, etc. Code requires footings be minimum of 48" deep so I'l probably make them a little deeper and start my foundation wall at 5' of depth to gain a little headroom in the basement area.

In Energy efficiency and durability | Asked By David Williams | Jun 21 17
7 Answers

Are gaps in double top plates an issue for airsealing?

Hello, I have a gap in my double top plate (see picture). Is this okay for an airtight approach? I plan to tape my plywood sheathing.

Should I just fill this gap with insulation or fit in another piece of wood?

In Energy efficiency and durability | Asked By Rocky12 | Jun 20 17
10 Answers

Completely insulate / cover a window in an open cell foamed attic?

You guys answered a lot of questions for me last year during my retrofit of open cell foam in the cathedral attic of a 20 year old home I bought. For the most part, things are great, but the dehumidifier that I have in the attic still seems to have to work way too often to keep the humidity around 50% even though I also have a couple of registers cut inline on the supply trunks up there as well.

In General questions | Asked By John Sexton | Jun 20 17
23 Answers

Exterior foam and fires

There has been a fire that gutted a high rise apartment building in London. It appears to have spread through the foam-filled exterior cladding panels. Similar fires have occurred in tall buildings in Dubai.

While the situations aren't directly analogous, I wonder if there are any lesson here for builders contemplating the use of exterior foam?


In General questions | Asked By Malcolm Taylor | Jun 14 17
18 Answers

Attic conversion - modified cut and cobble

I would really appreciate any assistance can provide me with my unvented attic.

I have a modular house in climate zone 5:

The sealed plans for the house specify attic truss construction:

I somehow ended up with something more like this:

At any rate, I'm going to restore the structure to the original plan. As you can see, the roof doesn't feature a ridge. The pitch is 9/12 and the rafters are 2x8 (truncated to 2x4 at the top, but I'll fur that part out to 2x8).

I'm planning the following roof assembly:

-synthetic slate tiles (existing)

In Green building techniques | Asked By Ben C. | Jun 17 17
4 Answers

Polyisocyanurate boards on the interior of a wall

Hi all, I've been doing a lot of research on this site and have emailed back and forth with Thermasheath to see if this is a wise thing to do.

I'm remodeling my ranch house which has brick veneer and 2x4 construction. The brick veneer really makes applying the foam to the exterior impractical.

In Green building techniques | Asked By NBMTX | Jun 18 17
11 Answers

Cooling Load Calc for Sizing a Ductless Minisplit

Last winter, I received a heating & cooling load calc for my house. For cooling, the design temp was set to 93F and the indoor temp to 72F, however the ASHRAE design temp for the Detroit area is actually 87F, and I've read that indoor temp for cooling load calc should be set to 75F. In other words, the HVAC guy was erring on the side of oversizing, which apparently is very common.

In General questions | Asked By Nathan Efrusy | Jun 9 17
14 Answers

Heating a well insulated small home with only electricity

Hoping someone can offer recommendations for our current heating situation.

We are building a very efficient cottage that will be lived in year round. We're having an issue on deciding how to heat the home. We will have a backup wood stove but I don't want to rely on the stove. The issue is we won't have access to gas, electric will be our only method for heating besides wood/pellet.


1600Sqft over 3 floors including the basement

R40 Sip Panel Walls
R35 Basement Walls
R60 Sip Panel Roof
Triple Pane Windows
7kW-10 DC Solar System

In Energy efficiency and durability | Asked By DavidCalgary | Jun 19 17
3 Answers

Are Blueridge mini-splits any good?

Hi All,
Does anyone have any experience with Blueridge mini-splits? They seem to be the house brand of Alpine Home Air. Any idea who makes them? Are they any good?

In Mechanicals | Asked By Ben Rush | Jun 20 17
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