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22 Answers

Insulated floor on top of concrete slab

I am considering building a slab-on-grade, or slab with short perimeter footers, superinsulated house in a cold climate. Most slab insulation schemes I’ve seen put foam insulation under the slab, often with fancy insulation schemes at the slab edge. I very much dislike having a hard, cold concrete floor (and, yes, even a 60*F concrete floor is cold to bare feet). Is there a simple cheap way to make an un-insulated slab with all the insulation placed on top of the slab, then a plywood sub-floor placed on top of the foam?

In General questions | Asked By Jack Woolfe | Jan 17 13
0 Answers

HVAC contractors: Please take this fault prevalence survey!

Not a question, but a request for the community:

I sit on an ASHRAE committee that is developing standards for automatic fault detection and diagnostics (AFDD) for rooftop package units.
We’re trying to gather data on the prevalence of various fault types (to help determine the cost-effectiveness of the AFDD systems). The head of the committee has put together a survey aimed at field contractors, to try to gather more information.

The more input we get, the better, so we would appreciate any contractors who would take this brief survey:

In Mechanicals | Asked By Brent Eubanks | Jan 22 13
0 Answers

Dan Morrison has a new job

My colleague Dan Morrison, who worked with me for years as a Fine Homebuilding editor and an editor (and my supervisor) at Green Building Advisor, has accepted a new job at Hanley Wood, a publisher in Washington, DC.

We'll miss you, Dan. Good luck with your new job.

Here is a link to the Hanley Wood press release:

In General questions | Asked By Martin Holladay | Jan 22 13
7 Answers

What would cause water dripping from a cedar cathedral ceiling?

No pipes are involved. There are 2 skylights, but the drips are also above the skylights . Only one side of the ceiling is involved. The room has a ventless gas fireplace. Would this cause the problem?

In General questions | Asked By thelma mears | Feb 11 10
11 Answers

Ventless propane heaters in crawl space

I just looked at a residential repair job (replacing leaking skylights) and the homeowner showed me some work that was recently completed in their crawlspace. A contractor had installed two ventless propane heaters in an uninsulated crawl space to supposedly save energy!

It is a second home with electric resistance heat at over 5,000 feet in the North Carolina mountains. The crawl space has an incomplete vapor barrier, sealed vents and obvious moisture problems with mold and non PT sill plates starting to rot.

In Energy efficiency and durability | Asked By Travis Thompson | Sep 25 10
8 Answers

Suggestions for insulation on ceiling of wet crawlspace?

For a super insulated house being extensively retrofitted in South Jersey(r40 walls, r70 attic, triple pane windows) with a permanently wet crawlspace (riverfront, high water table), I am considering insulating the ceiling of the crawlspace.

In Energy efficiency and durability | Asked By Michael Arnold | Jan 19 13
1 Answer

Air-tight Construction Caused Plasterboard to Blow Out?

We had cellulose blown into a remodeled wall this week-end. Plasterboard broke open under the pressure. The installer blamed the air-tight construction. Does this seem right?

We re-built a wall in our home. The exterior plywood sheathing was caulked against the studs and the seams sealed with Siga Wigluv tape. The interior studs were caulked then Siga Majpell stapled and sealed with Siga Sicrall tape and Conservation Technology gaskets applied to boundaries where plasterboard was applied. The plasterboard was screwed in place per code and then caulked and mudded.

In Green building techniques | Asked By Deb Davis | Jan 22 13
6 Answers

Should balloon-framed houses with open crawlspaces be sealed?

Given a "historical" (ca. 1910) wall assembly, plaster/lath -> framing -> siding (no insulation, sheathing, or vapor barrier), does it still make sense to seal the crawlspace? Is it risky, much like adding insulation w/o also rebuilding the exterior wall to add a rain screen can be?

In Green building techniques | Asked By Matt Goff (zone 2A) | Jan 14 13
3 Answers

How best to insulate newly built garage with flat roof


I live in Chicago (city of), Zone 5, and I have a new detached 2 car garage 20x20x11. The construction is wood frame with metal siding, drywall finished on the inside. I'd like to heat this garage to 50F during the winters in a cost effective manner (both insulation cost and energy cost), but I also want to do this right and not cut corners. I plan to heat this garage with a small ceiling mounted gas heater, like a Reznor unit.

In Energy efficiency and durability | Asked By Brian CL | Jan 22 13
5 Answers

Blowing dense-packed cellulose into Larsen truss walls and open rafter bays

This is what is keeping me up at nights:

Larsen trusses have no stud cavity walls and in my building the trusses are also open to the rafter bays (i.e no top plates).

I assume it’s the resistance to the blow by the walls and plates of the cavity which enable the density. I will be blowing cellulose into spaces with no boundaries so how to do I get the density and how do I know I have reached it?

Is it all about feel (i.e. resistence to the hose) and sound (i.e. back pressure while blowing)?

In General questions | Asked By Oak Orchard | Jan 21 13
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