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7 Answers

Heated Floor Above unheated Garage


Here's a twist to the "How do I prevent a cold floor in the heated room above an unheated garage" line of questions.

I am building a garage in Ottawa Ontario and my builder has proposed an option to insulate and heat that sounds attractive but is apparently difficult to implement.

The ceiling is 16" open web truss system on 16" centers.
There is 5/8 T&G plywood as the top floor substrate.
There are uninsulated 5" ducts flush against the underside of the plywood floor feeding the heated space above.

In General questions | Asked By Gerry Overton | Oct 1 12
6 Answers

Kitchen Remodel in Seattle WA - allowing for make up air with 600 CFM downdraft

I have done much reading and questioning about the code compliance of allowing for make up air and am not clear on viable options in a remodeling situation. The kitchen has attic and crawl space. What might be the most common way to identify the best, economical solution to meeting the 2009 energy code in a remodeling situation?

In Building Code Questions | Asked By april bettinger | Oct 1 12
10 Answers

How to insulate stud walls and roof with OSB-wrapped XPS on outside already in place

We have a new construction garage with living space upstairs (room in attic trusses). We are in zone 4, about 10 miles south of zone 5.

The entire interior will be considered "conditioned space". The roof is metal over underlayment over 7/16 OSB over 2" XPS over 7/16 OSB on trusses. The walls are Hardie Plank over Hardi Wrap over 1/2 plywood over 2" XPS over 7/16 OSB over 2x6 - 24" o.c. studs.

Our insulating contractor has proposed the following:
Exterior walls within living space: R-21 kraft fiberglass.
Exterior walls outside living space: 2" closed-cell foam = R-21.

In Green building techniques | Asked By Ed Barnett | Oct 1 12
5 Answers

Installing Polyiso in attic living space

I am working on a renovation of a 1940's house in Norfolk, VA. I want to properly install the recycled 2.5" polyiso insulation I have in my attic. The attic is used as living space. I have 2 x 6 rafters and want to increase the R value as much as possible by cutting sheets to fit between the rafters and then sealing them with spray foam to replace the R 19 bat that was up there.

In Green building techniques | Asked By Mark Imbrie | Sep 30 12
14 Answers

Getting caught on the latest basement insulation recommendations

I have just done some reading on the site, getting caught up and saw a few articles specially discussing the issue of basement insulation etc.

This article hits on many of the key issues.


My question is in relation to us "Northerner's" who should be targeting R-15 per the article when adding insulation via the interior.

Currently with XPS and ISO your looking at apprx R -5 to 6.5 per inch

In Energy efficiency and durability | Asked By M S | Sep 28 12
3 Answers

Is radon mitigation necessary with well sealed foundation design for a passive or near passive house?

We are planning a near passive house in northern Vermont. Radon risk is small to moderate. Design includes 6" subslab XPS and 2" high density(60 psi) foam @ the footers + R 30 ICF's.
Is punching a hole in the slab/ subslab 6" foam for possible radon mitigation really necessary and worth the money?

In PassivHaus | Asked By Phil Lawson | Oct 1 12
3 Answers

What are the issues with breaks/holes in the foundation?

We are building a near passivehaus in Northern Vermont (6 inches subslab foam and trying to strategize surrounding the footers). I have concerns and questions about breaks or holes in the slab/foundation. Which are needed and which are not? It seems anything that only communicates with the outside should be OK: septic venting/ air intake for wood stove.... but what about others such as slab/foundation drain or venting for radon mitigation?

1) Slab/ foundation floor drain

2) Radon mitigation pipe for venting

3) Septic venting

In PassivHaus | Asked By Phil Lawson | Sep 24 12
7 Answers

Is a LP hot water tank enough to heat my renovated house?

I'm doing a deep energy retrofit on a 2000 sf ranch in Connecticut. I've having trouble getting a HVAC company interested. The first wanted to put a hi efficiency air to air heat exchanger in the attic and use the 40 year old ducts. Another said it needs a 4 ton system and he'd only consider it in the attic....on and on.... I finally got a guy who said he'd put in a 2 ton system if that is what I wanted. None of these guys care to do any calculations I guess. My calcs show a 2 ton cooling load and a 54k btu/hr heating load.

In Mechanicals | Asked By Walter Gayeski | Jul 21 12
1 Answer

Level of damp proofing for perimeter foundation under slab?

I am curious how much damp proofing is recommended for a perimeter foundation around a slab that is poured about 20 inches above pre-existing grade. I am building in an area with a high water table (12" down) so we excavated down about 20 inches to sand across the whole building site and beyond the foundation by 2-3 meters and then levelled out the hole with 10 - 16" of 3" rock. The footings were placed on top of the rock and then 20" foundation walls.

In Green building techniques | Asked By Patrick Walshe | Sep 30 12
7 Answers


Is there an energy efficient skylight? I was thinking about a unidirectional skylight (e.g. lean-to, sawtooth) that only faces one direction for whichever use I want to use it for whether it be daylighting or passive solar. However, no one makes these that I can find in the U.S. The skylights would of course have glass only on one side or in one direction. Most companies that say they do custom are B.S. ers. Most of them can't conceive of puttling glass on only one surface and blocking off the other. Anyway, I am no expert either so ...........???anyone? Thanks

In Green products and materials | Asked By Lisa Young | Sep 15 12
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