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4 Answers

Venting an existing flat roof

We have a row house in Chicago. The drawing indicate (it seems it was built as drawn) that we have a 1/4" per foot modified bitumen roof. We don't have soffits or ridges (just parapets on three sides and a gutter along the back). The roof structure is min 16" wood roof trusses at the low gutter end and they get bigger at the front. We have R49 Green Fiber blown in cellulose insulation in the trusses. There is no vapor barrier (as the insulation suggested) and there is two layers of 5/8" drywall at the ceiling. We have mushroom vents at 1 sq. ft. of net free area for every 300 sq. ft.

Asked By Trisha Megan | Oct 8 15
3 Answers

Fantech MUAS

Is anyone familiar with this product/strategy? We are working on a custom home in Louisiana and are interested in utilizing it. We discussed a make-up air for the range hood when the fireplace damper is open, and we're thinking that this might be a good solution. I'd appreciate your feedback. Thanks!

Asked By Heather Gayle Holdridge | Oct 9 15
5 Answers

Moving a gas water heater into the envelope of the home...or switch to electric?

I just acquired a early 90's home and it turns out we can't get our minivans into the garage! On one side we have the HVAC equipment and on the other the water heater (both are gas). The HVAC I think we can relocate to an area of the bonus room directly over the garage so there will be minimal adjustment needed to the duct work. The logical place to relocate the water heater will be just inside on the same wall it is now which is currently a laundry room. I have never had a house with gas units inside the envelope of the home. So....

Asked By Andrew Bennett | Oct 9 15
23 Answers

How is thermal bridging prevented?

The construction process of our home, in southeast Iowa, was completed in January 2014. The house has fiber cement lap board siding and an interior spray foam insulation. In March of 20014 we noticed moisture accumulating, in a vertical line pattern, on the east elevation of the house.

Asked By S. Schneider | Oct 5 15
11 Answers

Below grade XPS placement, protection, and detailing

I'm pouring a traditional 8" concrete foundation for a client this week. They planned to have us place 2" of XPS foam on the outside of the walls for insulation. Once they can afford to finish the basement, they would place another 2" of foam on the inside of the walls between treated 2x2s and sheetrock over it for the finished assembly.

I've attached a rough sketch of the various components.

Asked By Nethaniel Ealy | Sep 16 15
22 Answers

Insulating plumbing vents and drains?

Is it worth the expense and time to insulate drains and vents? Essentially they are outdoor spaces inside your envelope? Just trying to decide before closing up some walls.

Asked By Lance C | Sep 10 15
9 Answers

How to use water for thermal mass

I have a room in the basement that has a large south-facing window. We don't really use this room but it would be nice to use the solar heat that collects in there to warm the basement. What is the cheapest way to use water as thermal mass? If tubes are the answer, what kind of tubes? If a barrel, what color? Can I use black plastic 55-gallon drums? Thanks for you help!

Asked By Beth Sorrell | Dec 13 10
8 Answers

Slab against rim joist detail please

New construction: back patio will be a slab poured against the rim joist so it is nearly level with the door threshold. Rim joist will be 11 7/8" atop a retaining wall back-filled with gravel, so there will be good drainage. The patio will be covered with a roof, and slope away from the door of course.

What's the best way to permanently protect the rim against water, moisture, and termites?


Asked By David McNeely | Oct 8 15
1 Answer

MItsubishi or Fujitsu, dual or single

I am renovating an 800 sq/ft Shotgun style house. I have had icenyne spray foam insulation sprayed throughout; ext. walls, attic, and crawlspace are all sealed. I am trying to decide what to do with hvac and am looking into mini splits. I prefer the ceiling cassette unit for looks. I am in the Louisville, KY area. The floor plan is mostly open with the living room/kitchen being one zone and the bathroom, bedrooms and utility room being separated with two doors.

Asked By Erich Popp | Oct 9 15
0 Answers

Gree Mini-split heat pumps

I'm hoping Dana will weigh in on this question given his expertise with specifying and analyzing mini-split heat pumps.

There are some new heat pumps on the market from Gree that appear to approach the performance of the best units from Mitsubishi and Fujitsu. It appears to me that the cooling efficiency is right up there with Mitsubishi and Fujitsu, though the heating efficiency isn't as good. They do however specify heating capacity down to -20 degrees F.


Asked By Joshua van Tol | Oct 9 15
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