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3 Answers

Unvented rainscreen?

Great website. Thank you! I am building a home on my farm in CA (zone 4B). 2x6 construction on top of a 4-inch concrete slab on pandeck over an ICF daylight basement. Incorporating passive solar concepts, going off grid with a 4400 watt array. Heating with a woodstove in our wet and mild winters (very rarely gets below 20F). Hoping a tight envelope, R-25 walls and an R-36 roof, thermal mass in the slab, and opening all the windows during our generally cool-ish nights will keep us comfortable in our very hot and dry summers (regularly over 100F during the day).

In Green building techniques | Asked By Galen Weston | Feb 19 13
19 Answers

Looking for help designing a durable & efficient wall for a house in the mountains near Asheville NC at 4,000 ft. elevation

I am trying to use articles from this site and from Building Science to design a durable and efficient wall for a residence in the mountains near Asheville NC at 4,000 feet of elevation.

Which would be a better wall; a 12" AAC wall with interior plaster and exterior stucco, or an 8" AAC wall with 3" of closed cell spray foam or XPS sheets on the exterior and then a 1" air/drainage space and then hardiplank? Would the increased complexity and cost of the second option be worth it? Are there any good spacers for the air/drainage plane that are not thermal bridges and will not corrode?

In Energy efficiency and durability | Asked By Stuart Murray | Feb 11 13
3 Answers

ERV with filter MERV 13 or greater?

Hi, does anyone know if there is an ERV with a MERV 13 or greater filter?

In Mechanicals | Asked By Ed Siff | Feb 20 13
10 Answers

Can polyethylene on top of your rainscreen prevent inward solar vapour drive?

I am working on a wall design for a super efficient home (near Passive House standard). The double stud wall with cellulose insulation, and a fibreboard exterior sheathing (no polyethylene vapour barrier on the interior) will- in places- have a stone veneer as the exterior cladding. Because we live on the west coast of British Columbia (similar climate to Seattle), and because some of the walls are south and west facing, I am concerned about inward solar vapour drive.

In Energy efficiency and durability | Asked By Burke Stoller | Feb 19 13
10 Answers

Bathroom Exhaust Fan drafts...


I was wondering if folks had any suggestions as to how to reduce cold air infiltration/drafts from bathroom exhaust vents.

I've found that in some of my bathrooms, cold air is coming into the bathroom from the overhead ceiling exhaust fan. When I go outside, I see that the exhaust pipe has a simple damper on it. I imagine that when the wind blows, it can easily get up and into the exhaust duct and the damper doesn't stop it.

Are there products that can help resolve this issue?


In Energy efficiency and durability | Asked By Morris Scott | Feb 20 13
14 Answers

Plaster on poured concrete interior wall?

What kind of plaster can I apply directly to a poured concrete wall? Insulated on the outside, new construction. Do I need something that breathes and gives with the wall as it dries out? Should I wait for a period of time after initial construction for walls to dry out?

Thanks---- Greg

In PassivHaus | Asked By Greg Gunderson | Feb 6 11
3 Answers

Cost to install exterior foam or Roxul?

I am curious about what the installation labour costs are for exterior insulation boards - foam or Roxul. For comparison, lets just say one layer that does not include taping or caulking. Does anyone have a cost per square foot of wall or floor area that they charge or have paid?

In Energy efficiency and durability | Asked By Patrick Walshe | Feb 20 13
6 Answers

EVR Systems

We have a newly constructed 2,600 sq. ft. home in San Angelo Texas area.
Home has 5 Ton & 2.5 Ton 16 Seer Train Units.
Home has Spray Foam Insulation at 6" Exterior Stud Walls and underside of Metal Roof.
Home has FMI Wood Burning Fire Place with Damper & Freshe Air Lever.
We are getting smoke in the house from the fireplace.
Occurs when we open the front door which is adjacent to the fireplace.
We are being told the house is to tight and we need a EVR Unit??
Please advise.

In Mechanicals | Asked By Ron Fallin | Feb 20 13
10 Answers

Indirect Water Heater Vs. Electric Resistance Preheater

Quick question regarding overall efficiency.

My incoming domestic water is around 40 degrees F and my boiler is unable to heat it up to a temperature that is warm enough for showers. I was thinking of two options.

1. Installing a electric resistance 30 gallon preheater. This would preheat the incoming water to around 60 degrees or so before it was fed into the boiler to bring it upto temp for showers.

2. Install an indirect hot water heater tank.

In General questions | Asked By Kevin Lauscher | Feb 19 13
7 Answers

Is sheathing a metal roof necessary?

I'm a carpenter here in Asheville,NC zone 4/5 and trying to design a home for myself so I need to make it as inexpensive and green as possible. I'm thinking of a shed roof using flat trusses with blown cellulose to R-60 and a metal roof. Of coarse, there will be eave and "ridge" vents. So do I need to sheath the roof for metal or will just using purl-ins work. My main concern in condensation. If you dont think this would work could you suggest other systems that would be inexpensive labor is less an issue since I will be doing most of the work myself.

In Energy efficiency and durability | Asked By terrell whitworth | Feb 20 13
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