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

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4 Answers
Is the aging of urethane foams considered off-gassing?

So I'm a bit confused here. My understanding of urethane foams (e.g. closed cell spray foam or polyiso) is that the blowing agent gases trapped within the closed cell structure slowly leak out over time and is replaced with air, depreciating the R-value. But then I see that certain companies advertise that their polyurethane spray foam products/kits do not off-gas. Is the leakage of the blowing agent not off-gassing, or is the manufacturer making a false claim? I'm assuming that they use an HFC blowing agent. Maybe I'm just missing something.

In Green products and materials | Asked By Mike LaCrosse | May 31 13
7 Answers
I had solar panels installed and would like to eliminate my oil burner and use electric to heat the water for the baseboard

Was thinking of heating with a 50+ gal electric water heater or on demand. Not sure if this is the best option. Electric is not an issue because of the solar panels, just not sure if a water heater will be hot enough and keep up.

In General questions | Asked By Ed Stewart | May 29 13
9 Answers
What is an optimal HVAC strategy?

I continue to plan for my new home (Zone 3) and am now focusing on the HVAC system. Here is what I think I understand at this point. Let me know if I am off base.

- Local code usually requires Manual J, but individual inspectors may or may not ask for evidence of one to issue a COO.
- Most contractors do not perform Manual J calculations correctly, if at all.
- A third-party HVAC designer is more likely to provide an accurate Manual J (at a cost of .50 to .75 per square foot).

In Mechanicals | Asked By Steven Knapp | May 29 13
6 Answers
2 questions for Martin or anyone else who knows

1. I've just become aware of a manufacturer's claim that radiant barriers can lose effectiveness over time, either from oxidation or other deterioration. Is this true? If so, do there exist any sheet products that you believe would remain effective indefinitely in typical deep south attic temperatures?

2. I enjoyed your water heater article in the current issue of FH. Which of the steel tank models you evaluated have an easily-replaceable anode rod?

Thanks very much.

In Energy efficiency and durability | Asked By charles CAMPBELL | May 26 13
4 Answers
Kitchen ventilation questions

Working on installing a new kitchen, now. The house has been closed-cell soy foamed, with excellent tight windows now installed. The space is wide open -- roughly 2,400 square feet.

Please advise on the level of clear thinking regarding island ventilation over the 5-burner gas cooktop. We're thinking of foregoing an ugly large stainless Zephyr hood for a simple flush grate directly over the cooktop, 5.5' over the burners, (with inline fan located in the attic, and vented directly outside -- less then 20' with one 90 degree angle).

In Mechanicals | Asked By gary scheft | Nov 3 11
2 Answers
Refrigerator EMF?

My daughter just moved to a place where the refrigerator back is on the other side of a wall, and only about 4 to 5 feet from the foot of the bed. I think there is also a TV on that wall (behind which is the fridge)

1) Is that distance enough, EMF-wise?

2) Will having a TV (the new kind) mitigate or enhance the EMF from the back of the fridge?

3) Is there a device which can fix the EMF coming from the fridge, and where to place it if there is?

In GBA Pro help | Asked By Donna Armstrong | May 29 13
1 Answer
Hot water pipe

I think there is a hot water pipe under the floor in the bathroom that also extends into the living room area (this is an efficiency apartment), where I sleep. When I woke up I noticed towards the foot of my sleeping bag (I sleep flat on the floor on an opened up sleeping bag because of my back) the rug was actually hot in that spot and it corresponded with the hot spot in the vinyl floor in the bathroom so I surmised the above.

In General questions | Asked By Donna Armstrong | May 29 13
1 Answer
Heated shop slab — energy-efficient transition at garage door?

Climate zone: Canadian Zone B. Would be a US zone 5B. 3850 HDD and dry.

I am building a shop with a heated slab. The slab will be insulated at the perimeter (via ICF foundation/stem walls) and underneath to try to thermally isolate the slab from ground and exterior.

The slab has two exterior transitions: a person door and a car door.

In Energy efficiency and durability | Asked By Mark Kornell | May 29 13
5 Answers
Mold removal

I would like to know what the safest most effective product is used to remove mold from wood.
I have mold in my attic and want it out. When hiring a clean up company what questions should I be asking about the method of clean up they employ? My husband wants to clean it, but I think because of the location and extent of the mod,it covers the whole length of the attic roof,I think we should find someone to hire. I have cellulose insulation and I'm debating whether to remove it all and start over? How would I know if the insulation is salvageable?

Thanks,

In Green products and materials | Asked By sarah matheson | May 25 13
6 Answers
Azek PVC sheets goods over 1 1/2 foam board as siding

Looking for some feed back on a wall system i would like to assemble on an addition with very little wall space, Mostly glass windows

Wall system: From in to outer ,
1/2 blue board
2x4 wall 16 in OC
R-15 batt insulation with in wall cavity area
1/2 plywood sheathing
Outie windows installed on 1x material applied to sheathing
Tyvek house wrap
1 1/2 foam insulation installed, taped and foamed seams and edges
Tyvek house wrap applied over Foam and tapped seams and tapped to window nailing flange
Azek sheet goods as sheathing and trim around doors and windows

In Green building techniques | Asked By William Campbell | May 27 13
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