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2 Answers

Follow-up question on cut & cobble rigid foam in rafters

Several weeks ago many of you were kind enough to offer advice on a cut & cobble insulation project I undertook while converting our old garage into a new master bedroom. A quick update on my progress. After three long weekends and a few extra hours here and there, I have 8" of polyiso foam board fully installed (one layer between the rafters, one layer beneath). Both layers are ~95%+ airsealed (I now need to find an effective way of locating any last remaining leaks). The room is still unheated but the difference is palpable.

In Energy efficiency and durability | Asked By Brian Gray | Feb 4 15
4 Answers

How to insulate a cathedral ceiling under an exposed metal roof?


In GBA Pro help | Asked By Jennifer Duffy | Feb 2 15
3 Answers

What size point of use water heater should be used to heat water for my washer?

I have a high efficiency Whirpool washer in my detached garage. I plan to use a tankless point of use water heater for those occasions when I need warm or hot water loads. What are the specification for a water heater to meet my needs?

In General questions | Asked By Trudy Urdal | Feb 4 15
13 Answers

What is the efficiency of gas powered infrared radiant heat?

My project: Climate zone 6A Hortonville, WI 54944 Energy source: electric or propane, no natural gas available

An earlier post about heating garage brought up the possibility of gas powered infrared radiant. I'm familiar with these devices, but I literally can't find any information from the manufacturers regarding their efficiency. They all claim to be "very efficient" for various reasons, but I can't find hard data.

Are they rated by a percent like house furnaces? I.E. Are they in the range of 80% efficient ceiling hung unit heaters?

In Mechanicals | Asked By Rick Van Handel | Nov 24 14
4 Answers

Tar used for interior concrete sealing

I'm in the middle of a residential new construction project, targeting Passive House requirements. It is an insulated slab on grade, double-wall stick built home, where the air barrier is on the outside/exterior wall. There is no vapor barrier, and there is an approx 20" cavity for dense-pack cellulose. We just finished air-sealing, and my builder coated the top of the concrete slab in between the double walls (20" of concrete) with 10 gallons of Henry's foundation coating. Of course, this is an exterior-grade product that contains tar and a lot of nasty VOC's.

In Green products and materials | Asked By Eric Merkt | Feb 2 15
19 Answers

Minisplit setup for New Jersey, 750 sq. ft. house over crawl. Bouncing my HVAC contractor's plan off you guys.

The short. I have a 25x30 rancher over a currently vented crawl. It sets almost perfectly south facing on the 30ft long side. No tree shading on south or west. Deciduous tree shading in the east and some on the north side. It's two bedrooms one bath, kitchen and living room. Standard stick frame 2x4 construction and vinyl siding. House was built in 1963 in a post WWII development.

Bedroom1: 10x12
Bath: 5x9 rough estimate
Kitchen: 9x11
Living: 14x14 rough.
Short hallway off living room with bedrooms at the end: 4x7

In Mechanicals | Asked By Lance C | Jan 16 15
3 Answers

How much energy is lost due to indoor sourced air for combustion in a furnace?

I used to have a 75k input (60k out) 80% furnace that used basement air for combustion, in addition a vent was broken dumping a lot of heated air into the uninsulated crawlspace which is where a large amount of air leakage is in this house which was feeding the furnace.

In Energy efficiency and durability | Asked By Alan B | Feb 2 15
2 Answers

How to best seal well water line in PVC pipe coming up through slab.

Our foundation is a monolithic slab on grade. The well water line (1.25") and electrical line (1") enter horizontally under the slab and then vertically up within a 4" PVC pipe (via two 45 degree elbows). Not sure if this was the best method vs just embedding in the slab, but the thought being that it would be possible to replace the water/electrical line in the future if needed.

I'd like to seal up the space in the 4" PVC pipe, mostly just the top area from within the house. I'm not concerned about bulk water intrusion.....just air sealing and moisture barrier.

In General questions | Asked By Brian Post | Feb 2 15
9 Answers

Help to plan foam insulation with AC ductwork inside 4 1/2" high rafter bay cavity in roof assembly.

Our house was built around 1850 and has no insulation or air sealing in the roof. The finished attic has a partial cathedral ceiling, and the high velocity 4" AC flex ductwork runs from the air handler which is located behind a kneewall in the attic, up one side of the cathedral slanted ceiling (7ft), across the flat part of the ceiling (about 10ft), and partially down the other side of the slanted ceiling, through rafter bays which are only 4 1/2" deep, due to the very old house construction. Ceiling material is plaster lathe.

In GBA Pro help | Asked By James Berry | Feb 2 15
22 Answers

Poly on interior wall

I was talking to a builder who said the key to having an energy efficient interior is to use 6 mil poly on the walls before installing drywall. He said you carefully tape around all outlets and seal off the holes.

We are in Zone 5, and although that sounds like it would be a great air barrier, I fear I would be making a mistake to follow his advice.

I am planning a house build with 2x6 studs and the following details. I will use a cheap vinyl siding, good tyvek house wrap, 3M tape on the seams, 5/8 OSB, 2x6 studs, mineral wool or fiberglass rolled insulation, then drywall.

In Energy efficiency and durability | Asked By Nicholas C | Jan 31 15
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