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8 Answers

Will air supply ducts in a poorly insulated wall present a potential moisture problem?

These are warm air supply ducts (3.25 x 10) in a 2x4 wall with just 3.5" fg batt insulation. The ducts are against the interior face of the exterior board sheathing. This house has not been occupied in the winters (coastal maine) but is being renovated to be year-round. Prior to demolition we had planned to foam the wall cavities where interior finishes were stripped but did not know the walls were only 2x4. Will warm air traveling thru these ducts condense its moisture on the inside of the duct or cause condensation at the sheathing plane?

In Mechanicals | Asked By todd Stanley | Oct 21 11
5 Answers

PH Cooling Options in High Mountain Desert?

Heating my Salt Lake City based 1010 PH project [1], with 5765 heating degree-days (F), does not seem to be a problem with largely passive solar gain; however, the 1047 cooling degree-days (F) are a concern [2].

In PassivHaus | Asked By Jan Nielsen | Sep 2 12
8 Answers

Bathroom exhaust vented to soffit?

We live in North-central Alberta where it can be very dry but has been humid this year. Winter temps can reach -40 C. We will be replacing our 3-pc bathroom exhaust fan (and ducting) with something more powerful and Energy Star rated. Currently it is vented through the soffit which I've been told is allowed here. But my insulation contractor wants to vent it to the roof since I am replacing everything. I am a little worried about leaks and condensation and snow in winter if I do that but also about the moist air re-entering the attic through the vented soffit if I leave it.

In General questions | Asked By Kim North-Central Alberta | Aug 26 12
2 Answers

Sizing AC

We are building a concrete ICF home in a constant hot climate ... using ductless a/c ... have been told by the ICF people that A/C may not be necessary ... I'm not buying this ... at least in bedrooms ... what size a/c in the bedrooms ... will 6000 btu work ? smaller/larger

Thank you

Tom Good

In Mechanicals | Asked By Thomas Good | Sep 4 12
1 Answer

Does having a thicker wall thickness mean that OSB sheathing can not be used?

With a thicker wall thickness, the exterior side of the wall will be cold, and stay cold longer. Look at any thermal analysis. Using OSB as your exterior sheathing might be a good idea since it is more susceptible to moisture, correct?

In Energy efficiency and durability | Asked By Nathan Pozzesi | Sep 5 12
17 Answers

Alternatives to foam under slab or no slab?

Are there any alternatives to foam under a slab that might be "cost effective". I realise that CE is a very loaded term, so don't get bogged down in that term.
Obviously, I am not interested in VIP's. But how about the cost and performance of Perlite? Are there other alternitives?
I am looking at a Passive House in a 5, maybe 6, climate zone.
XPS may be available to me at a reduced cost because my wife works for a large company that makes the stuff. Am I wasting my time looking at alternative insulation products if I can get XPS at a discount?

In GBA Pro help | Asked By Steve Young | Aug 23 12
2 Answers

PEX Materials and strategies

Are all PEX products equivalent? Are the variety of connection methods all reliable through time?

Currently, I am working on my rental 3 time zones away from my tools (modern life...) so the push-fit connection option would be desirable. But can I leave the job and return home with confidence?

Thanks for sharing your voices of experience!

In Green products and materials | Asked By David McNeely | Sep 4 12
2 Answers

Rigid Insulation Between Double Studs


I was wondering if someone could check me on my proposed wall assembly and provide recommendations if I'm off base...

I"m planning on utilizing a double stud wall assembly, two rows of 2x4 studs at 24" O.C. with a 3" gap between. The two stud bays will be filled with Roxul comfort batt. The exterior will be sheathed with 1/2" plywood and covered with housewrap. The siding will be lapped fiber cement board. Interior is latex painted gypsum drywall.

In Green building techniques | Asked By Brian Beaulieu | Sep 4 12
1 Answer

How do you work out the R-value of loose cellulose?

Have roof filled with Insulation and need to work out it's R rating

In Energy efficiency and durability | Asked By Colin Mendoza | Sep 4 12
16 Answers

Wall Moisture without Vapor Retarder In Cold Climates

Its well known that improper use of vapor retarders can prevent walls from drying out properly and leading to moisture related issues such as mold and rot. Is it uncommon to have moisture issues in wall due to air leaks or vapor diffusion if the vapor retarder is left out? Would there be a concern with moisture issues for a standard construction wall (siding, plywood sheathing, 2x4 or 2x6 frame, fiberglass or cellulose insulation, drywall without vapor retarding paint) if the vapor barrier is not used in cold climates? Would this meet code in the Chicago area?


In General questions | Asked By Ed S | Sep 1 12
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