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2 Answers

Weird top-plate area idea

New England is going through a helluva winter, and has turned into
a festival of ice dams across much of the Northeast.. [Go here for
a small artistic study thereof, and some other winter fun.] What
strikes me as a common problem that may contribute to this is the
difficulty of effectively insulating over the top plate of typical
roof/wall construction in vented-attic scenarios, invariably leading
to significant heat loss right above the eave where it's most critical
to *not* warm the roof surface.

In Green building techniques | Asked By Hobbit _ | Feb 18 15
3 Answers

Foil-faced polystyrene and WRB

I believe it's suggested that the WRB be placed as close to window plane as possible. With the shrinkage problem associated with rigid foam , a house wrap may be a better choice. So...if you use foil faced polystyrene then cover it with a house wrap.....then have a rain screen space.....doesn't the wrap negate any benefit from the foil facing.

In Energy efficiency and durability | Asked By Robert Brown | Feb 17 15
7 Answers

Moisture problems with double-stud walls

I have read the article on double-studded walls very carefully. Moisture elimination is one of the issues that I am trying to resolve in my mind before attempting a low-energy home.

I am considering using the six-inch wall with staggered 2X4s since it reduces the thermal transfer by approximately 20% in my calculations. The design that I am considering is as follows:
•Cement board siding
•One-half inch vented rain screen
•ZIP System R3 as the exterior sheathing to replace OSB, Tyvek and blue-board insulation

In Green building techniques | Asked By Larry Hanneman | Feb 15 15
3 Answers

Indoor air quality in a ventillated NZE house when power goes out

We live in a NZE house of about 34795 ft3, and it has a ACH50 of 0.46 - the actual number was 269 cfm @ 50 pa. The Zehnder ventilation is set to 144 CFM. 4 bedrooms 3.5 baths.
If the power goes out, do we need to worry about suffocation? I would prefer not to open windows, to maintain the heat in the house for as long as possible. - the power goes out in the winter, usually. Has anyone done any studies on the indoor air quality in such a situation?

In Mechanicals | Asked By David Hobart | Feb 16 15
2 Answers

Is low density foam under the sheathing the right type of insulation for attics?

I live in zone 4B and have a house with 3 tab shingles. Recently I was given a proposal from a company that offers energy performance and one of the recommendations was to apply 8" of low density foam under the sheathing with no mention of creating any type of ventilation in between the sheathing and insulation.
The second recommendation that they proposed was to put 2" high density foam on the rim joist.
Is the low density foam the right type of foam to apply under the sheathing and is ventilation needed between the foam and the under sheathing?

In GBA Pro help | Asked By Joseph Samsonowitz | Feb 17 15
1 Answer

Detached garage - outswing or inswing door? Commercial or residential door?

On a detached garage would it better to install a steel door with a steel frame OUTSWING door or just a standard wood/fiberglass INSWING residential door?

In General questions | Asked By Peter L | Feb 16 15
3 Answers

Building envelope


We live in southeastern Wisconsin and are currently a year into a complete gut/remodel of a home built in 1963. We have the interior complete and are living in the home (family of 4).
We are about to have the siding installed (LP Smartside lap siding) and have a few questions/concerns.

- 2x4 wall construction (16" centers)
- interior spray foam closed cell urethane on all walls with no interior vapor barrier
- attic insulated with loose fill blown in fiberglass insulation R-50 with interior vapor barrier

In Energy efficiency and durability | Asked By Kevin Steltenpohl | Feb 16 15
1 Answer

Repurposing HRV from radon mitigation to building ventilation duty

Previous owner installed HRV to deal with radon. It was ineffective, since shutting it down had only couple 10th effect. I have installed radon mitigation system and knocked it down from 11 to 1.4.

So now I have a lovely Honeywell HR200b1005 200cfm unit collecting dust.

My plan is to keep it in the basement and instead run stale air ducts to kitchen (1st floor) and top of stairs of 2nd floor with fresh air ports running to three bedrooms on 2nd floor distributed by duct I put in insulated conditioned kneewall that connects them.

In General questions | Asked By Apollo S | Feb 16 15
29 Answers

Rheem's condensing water heaters (storage)


My 14-year-old electric water heater is starting to look a little long in the tooth. Time to upgrade.

So, I'm looking for intel on Rheem's Professional Prestige Series: High Efficiency Condensing Power Direct Vent (RHE50) or its sister sold by Home Depot - Rheem EcoSense High Efficiency Power Direct Vent (ECORHE50).

I can't find any online reviews of either product (save one favorable review on HD's site).

For several reasons, I'm looking at a high efficiency storage water heater instead of tankless.

In Green products and materials | Asked By Michael Brahmey | Oct 11 14
12 Answers

Makeup air in all electric home?

I have read a lot of blogs and questions that, quite reasonably, recommend makeup air for kitchen exhaust fans in tight homes. The use of these fans can cause backdrafting in combustion appliances. But what if the home does not have any combustion appliances? We typically design very tight homes, around 1 ACH(50) with no combustion appliances. We use heat pump water heaters, Mitsubishi mini splits, and electric condensing dryers. We also use Induction ranges and cooktops. No fireplace. We tell our clients that if they want a fireplace, they can have one...outside.

In Mechanicals | Asked By Rob Shearer | Feb 11 15
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