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7 Answers

Deep energy retrofit — Envelope upgrade questions

We are well into the process of a deep energy retrofit for our 2,700 sq. ft. house in NYC suburbs, zone 4/5A. The house is a typical 1988 contemporary with 2x6" wood frame construction, builder grade, sloppy subs, code minimum and 25 years of neglect. Long story short, we are currently replacing the roof, windows, doors, siding and HVAC. Before we started renovations, the blower door test result of just under 11 ACH50, proved that the envelope could be improved, so that is now our focus.

Asked By Andrew Wuench | Mar 31 15
1 Answer

Gravel under concrete footing

I am trying to finalize several aspects of the foundation design for the high-performance house we’ll be building in central Vermont starting in May. Typical of the region, our house site, which has a 7% slope, is near the bottom of 600 foot ‘mountain’ and we expect it to be moderately wet (Buckland very fine sandy loam soil that is only “moderately well drained”).

Asked By Timothy Denny | Apr 1 15
1 Answer

Replace AC with a heat pump?

I've recently inherited a house in Virginia mountains, climate zone 6, that's been used as a three-season retreat. I want to keep it open in winter. Heating is via coal-guzzling electric baseboards. Conventional AC w/ exchanger in unconditioned 3rd floor attic and flexiducts.
1) Can i replace the AC w/ newest generation heat pump like those used in mini-splits? Local HVAC folks are not familiar w/ the technology, since climate is too cold for conventional heat pumps

Asked By Jerry Knight | Apr 1 15
10 Answers

Attic insulation reality check

It's time to get my attic air sealed and re-insulated and I've committed to hiring it out since the 6/12 pitch truss attic is a horrible place that I hate to work in. I'm having trouble finding people willing to blow cellulose. Everyone around here seems to want to blow fiberglass. Is this a major issue?

The first bid I've gotten is $3.20/sf for attic floor air sealing and R-30 worth of blown fiberglass. Sane/insane?

Asked By Nathaniel G | Mar 26 15
0 Answers

BuildingGreen publishes special news stories for April 1st

Here's a link to one of BuildingGreen's special news reports for April 1st:
Judge Robs Yost of Gold Medal in WUFI Modeling.


Asked By Martin Holladay | Apr 1 15
1 Answer

Is it wise to put a product like Drainwrap behind a layer of rigid insulation?

We are getting ready to remove the existing layers of siding from an old (100yrs. +) home that appears to have diagonal board sheathing attached to the studs.

Our intention is to blow cellulose into the stud bays, then cover the board sheathing with Drainwrap integrating the window flashing into this layer, then adding 1" rigid foam with seams taped, and finally adding 1x furring strips and either Hardi or Lp lap siding.

The project is waterfront on a coastal bay in Maryland. The windows in the home are vinyl replacements in original wood frames.

Asked By mike labesky | Apr 1 15
1 Answer

Best way to find the experts in my area

What or where is the best resource to find the top green architects/designers and builders in my area?

Asked By Mary Dorcey-Mussog | Apr 1 15
3 Answers

Foam under slab details

New residential construction, Zone 4A, slab on grade with attached garage. Three questions:

1. Most builders around here pour the entire slab flat; in other words, no slope to garage door and no step up into the house. Is this an okay practice?

2. I plan to put 2 ½" of foam sheets below the slab for R-10. Is there any compelling reason to continue the foam under the garage part of the slab (there would be no thermal break, the slab would be contiguous).

3. What is the detail for continuing the foam below bearing walls that will be supported by a thickened slab?

Asked By David McNeely | Mar 31 15
3 Answers

With taped exterior sheathing, is there any benefit to caulking each stud bay?

I have 1/2 cdx sheathing taped with zip tape. I takes the sheathing to all window rough openings as well. I was planning on caulking or applying acoustic sealant to the crack between the sill plate and the bottom of the sheathing and again at the top plates. The sheathing was not glued or gasketed at these joints.

Since all of the other sheathing joints are securely nailed to blocking and taped with ZIP tape I presume there is no point to caulking the stud bays?

Asked By Rick Van Handel | Mar 31 15
1 Answer

More wet fiberglass

Some of y'all might remember this picture...
and the discussion that went around it, concerning careful backoff
[from the wall] and sealing-up of the outer duct sheath to make sure
no water infiltrated into the fiberglass between. This was for the
intake duct on my HRV setup, the coldest part, and after retrofitting
same on my HRV setup accordingly it was fine all this winter.

So I was downstairs putting the snow shovels away [wishful thinking?]
and happened to bump the end of the *exhaust* side duct, which

Asked By Hobbit _ | Mar 31 15
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