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0 Answers

Cold air infiltration through a power-vented water heater

I was wondering if anyone has a solution for this problem.

I recently installed a power-vented natural gas water heater to replace a 20-year-old electric.

The installation was done by me and inspected by both a gas fitter and the local gas company. All is good...

However, there is a significant amount of cold outside air coming in the 2" (system 636) exhaust from the power vent, and its enough to spin the fan on the power vent backwards. (when not running of course)

In GBA Pro help | Asked By R Hunt | Jan 24 13
17 Answers

Summer sun control - Zone 6, Madison, WI

I'm advising the onwer of a 50 unit, 6 story multifamily building on how best to cost effectively control excessive heat gain in the summer. We started by looking into louvered overhang retrofits made from aluminum and attached to the 6th floor, south side units. ( The 1-5 floors have the balconies above them to shade some.) The price? $30,000 for 5 apartments. Not in anyone's price range. The existing glass is a tinted charcoal gray Insulated Glass Unit. For that reason, window film installers are saying that they can't guarantee the glass won't break if they install.

In GBA Pro help | Asked By mark faultersack | Jan 21 13
9 Answers

Moisture barrier for attic in brick house with slate roof?

I live in Zone 5a in roughly 800 sq. feet of living space in a duplex, part of a "development" of houses built in 1917 to house workers in war-time industries.

In Energy efficiency and durability | Asked By Deborah Goodwin | Jan 23 13
5 Answers

Venting flat roof with two thermal boundaries

I wanted to get your opinion on this, as I've heard differing thoughts. As an energy auditor in Phoenix (8 inches of rain / year, relatively low outdoor RH), I see a number of "flat" roofs with two different thermal barriers (foam w/elastomeric atop roof deck, and unfaced batt (or even faced batt) in the attic space atop the ceiling).

The attic space is usually between 20 and 30 Pascal @ CFM50, and many times, the attic is vented.

In Energy efficiency and durability | Asked By Jason Owsley | Jan 13 13
7 Answers

Who pays for fixing builder error?

I am building a house and I gave the builder the floor plan of house I wanted. I signed off on the plan, not knowing how to read a blueprint, not realizing the builder changed the entrance to the basement from my kitchen to entrance to the basement from my foyer. Also the arch from the foyer was to be wall-to-wall, it looks like an entrance from the foyer.

In Interior design | Asked By Burma Stewart | Apr 13 12
10 Answers

Why is more insulation still required in roofs than walls in very tight buildings?

In researching high efficiency buildings, and deep energy retrofits, I am confused why in a tight building, it is still suggested to insulate the roof/ceiling more than the walls.

In GBA Pro help | Asked By Matt Friesen | Jan 22 13
10 Answers

Basement Insulation / Vapour Diffusion


A couple questions: Would there be any drying issues with insulating a greener foundation (Nov.2012) on two sides with foam? - Are we asking for trouble at the sill ?

We were planning to heavily insulate our (new house) basement with XPS on the exterior only, but may end up with additional foam in some areas of the basement interior as well, depending on how it's to be used / finished. The small mechanical room, for instance, could get EPS (type II, 2 1/2'') under plywood on the interior.

In General questions | Asked By jessie pratt | Jan 21 13
2 Answers

The video of the “three old hippies” panel discussion

In early November 2012, I published a report on the Passive House New England symposium at U Mass Boston.

The video of the panel discussion (moderated by Jesse Thompson, and featuring three speakers described as “old hippies”) has been released.

The GBA article has been updated to include the video, which features Adam Cohen, Marc Rosenbaum, and me.

See it here: Passivhaus Practitioners Share Their Success Stories.

In General questions | Asked By Martin Holladay | Jan 22 13
1 Answer

New Construction Venting, 2:12 metal shed roof at wall?

Planning my new home construction. Modern design 2:12 metal standing seam shed roofs.
Zone 5/B dry R-38 minimum, I want more. + Can get 4' snow.

All 3 roofs will include TJI's running full length from eve to top. 5/8" CDX sheathing, 30# roofing felt with Gracy's Ice & water shield at eves.

Center great room/ kitchen (36' deep x 28' wide) will be18' high at front of house & 12' at rear, easiest to vent.

Both bedroom wing roofs will slope away from the center great room. They will both join onto the outside walls of the great room below its 2' overhanging roof.

In Energy efficiency and durability | Asked By james patrick | Jan 23 13
1 Answer

How can I fix a poorly ventilated cathedral ceiling insulated with kraft-faced insulation?

I am in the planning stages of renovating a home that has cathedral ceilings with 2 x 8 rafters and R-19 kraft-faced insulation. Ventilation is poor at best. There is frost on the underside of the roof sheathing.

I would like to turn it into a hot roof by sealing up any vents and either replacing the the insulation with closed-cell foam or adding 2 two-inch layers of polyiso on top of the roof deck (leaving the existing insulation in place). If I choose the latter, will I be trapping moisture with the kraft facing?

In Energy efficiency and durability | Asked By Frank Ball | Jan 22 13
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