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21 Answers

Bug screen for rainscreen strapping...how wide to cut?

I'm a rookie with this. First time building a rainscreen. I've got my WBB on the house and would like to apply my 3/8 strapping to create and airgap.

I picked up a few hundred feet of 4' bug screen and I will first apply a layer top and bottom, then my strapping and then staple the bug screen on-top of the strapping making the air gap, hopefully, bug free.

In General questions | Asked By Mark Helmrich | Mar 18 15
3 Answers

Air seal large gap around light fixture box

I've made it to nearly my last electrical box in the attic that holds a light fixture. I've used fire caulk for all of them, but this last one has a big gap on one side, probably a half inch wide.

Caulk won't work, it just falls in. I'm thinking either fiberglass mesh and duct mastic or UL 181 foil tape.

I have both of the above, I could buy Great Stuff Fireblock foam but since that still ignites at 240 degrees I doubt that's the best idea.


In Energy efficiency and durability | Asked By Jeremy M | Apr 7 15
4 Answers

Is rigid foam as sheathing cheapest way to meet code?

I know: it depends.
I found GBA's detail of 3/4 rigid foam on the framing with 1/2" ply-osb sheathing on top. this gives an easy nailing surface for shingles. So if I can use diagonal bracing, (steel or 1 x4) and xps foam and cellulose this will give me R= 22.25. (Good for Zone 5) and also 18.5+ 3.75. My question is now I don't have to worry about the condensation point because my sheathing is outside my insulation?

In Building Code Questions | Asked By Keith McGuire | Apr 9 15
2 Answers

My client has an old 1840s home that never had any kind of vapor/water barrier

It is simply clapboard nailed to studs. He gutted the old plaster wall, and had the stud bays spray foamed directly onto the old clapboards. A few popped loose on the outside, so they re-nailed them.
My question is: will the foam retain moisture and cause the clapboards to rot, or will he be o.k.?

In General questions | Asked By roger steinbrink | Apr 9 15
7 Answers

Cold storage room in a basement and a heat-pump water heater

So I'm planning to have a cool storage type room in my basement for food. We are heating with mini-splits, and will have 9.3 kW of PV solar. I'm considering placing a 80 gal AO Smith hybrid heat pump water heater in the cool storage room. Figuring if it is going to cool a room anyways, I might as well make it a cool storage food room, and insulate the floor above so it doesn't cool the floor above.

How much space(sq ft) should I allow for room the heat pump will operate in so that it works effectively? It can also be tied into our general storage room too - to allow for more space.

In General questions | Asked By brad hardie | Apr 8 15
0 Answers

Cost of European materials going down?

With the Euro getting very weak has anyone noticed materials from Europe getting cheaper? We weren't planning on getting quotes for European windows/doors because of price, but I was thinking that with the Euro plunging, maybe some stuff could be purchased 25% cheaper than a couple years ago.

In Green products and materials | Asked By Kristopher Steege-Reimann | Apr 9 15
2 Answers

What is the best way to build a 2x8 exterior wall and achieve R-40?

I am building a house near Toronto, Ontario. Winters are cold, and we do see our share of -20 or colder weather. Summers have been somewhat hot in last couple of years.
My wall section looks like this right now from exterior to interior.
Stucco>1"rigid foam board (taped seems)>2x8 studs @ 16"OC>2" closed cell spray foam> R24 Batt>6mm poly>drywall.
I am worried about any moisture getting in the wall so that is why I am considering doing 1" rigid foam board from the outside and poly from the inside.
Can anyone tell me if they have done anything similar.

In Energy efficiency and durability | Asked By Slobo Urosevic | Apr 7 15
5 Answers

I am concerned that spray foam, once installed, can become an accelerant in the event of a fire. Have there been any studies?

There was a new mansion built in Houston that had a fire. The house was completely destroyed. Spray foam was used in all the walls. I have not heard nor read anything about spray foam and fire.


In General questions | Asked By john winkler | Apr 8 15
15 Answers

Pricing per ton for GSHP and air-to-water heat pump

Is there a general rule of thumb for pricing of a GSHP and Air to Water heat pump for a medium sized installation of ~17 tons or 200,000 BTU/hr. $/Ton or $/BUT? What products fit this market segment?

Do you also have a general rule of thumb for an energy retrofit of a home in $/Ton or $/BTU reduced heating demand?

Is there an issue with using a GSHP in a climate where little cooling is required?

In General questions | Asked By Cathleen Dalmeida | Apr 4 15
20 Answers

Roof furring questions

When it comes to furring a roof, are 1x3 or 2x4 furring strips better to use? I assume the latter because they are stronger/wider and give a better grip area to the sheathing above. Spacing should be what: 12" or 16" on center?

My other question is with the sheathing above. I read that plywood is better than OSB although there has been a lot of problems at the lumber yards with plywood cupping. The lumber yard attendants said that the QC on plywood is really bad because it is so rarely used. I assume 5/8" sheathing is ideal for a metal roof?

In Green building techniques | Asked By Peter L | Apr 6 15
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