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8 Answers

Should we actively condition our unfinished basement?

We’re in SW Virginia, building a 2 story, 1900 sq ft home with a full basement. 2 inches of XPS foam under the slab, and 2 inches of polyiso on the interior of basement walls. Heat pump/forced air and woodstove will heat upper floors. Future plans include doubling the thickness of polyiso all around in the basement. Was also thinking that if we had cold floors on the first floor, I could add some insulation under the floor.

In Mechanicals | Asked By William Costello | Jan 17 18
16 Answers

Thought experiment: 30k cistern as thermal mass in passive home

Hi, we have a mountain lot in Colorado at 7500 ft elevation with lots of south facing solar heat gain, and we're planning on building a passive home. We're required to install a 30k gallon cistern for fire protection. A 30k gallon buried cistern seems to be extremely expensive, while a 30k gallon bladder type cistern is very cheap and could be installed inside the home's envelope in a crawlspace. Assuming the passive home is well balanced for on average for a year, could the huge amount of thermal mass help moderate an even temperate, or would it become a problem?

In PassivHaus | Asked By Mike AbiEzzi | Jan 9 18
4 Answers

Insulation question

Hello, The room above the garage in our house is much colder in winter (we live in Canada) and much hotter in summer than the rest of the house. We would like to insulate the space between the garage ceiling and the room's floor.

As the house 13 years old we have quite big of a space (drop ceiling ) to work with.

2 different contractors suggested different solutions:
1 - the foam spray (much more expensive option),
2- blown fiberglass.

In Energy efficiency and durability | Asked By Karina_Canada | Jan 17 18
2 Answers

Can foil-faced polyiso be used on the interior side of a CMU wall in South Florida?

I am building a house in South Florida that has the following Wall Assembly (starting from exterior and working in):

2" Stone Veneer
Hydro-Ban Waterproofing
8" CMU Wall
3/4" Hunter Foil Faced Poly Iso
1 1/4" Air Gap
Metal Stud
Drywall

In Energy efficiency and durability | Asked By Cevhh | Jan 17 18
4 Answers

Roof venting

I have a building with a completely closed ceiling/roof. This building is 70' long with a 12"x48" center beam and 2"x12" rafters (insulated) on 2' centers and has no soffit vents. Moisture has created a problem since I painted the ceiling.
How can I vent the roof without adding 35 vents per side of the beam. Thank you , Tom

In General questions | Asked By datum | Jan 17 18
10 Answers

Cold Wet Sheathing, Double-Studs WITH Vapor Barrier, or Not?

John's recent post about open cell foam in a double stud wall here:

http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-an...

...got me wondering about a VERY basic question. The articles linked to by Dana Dorsett refer to this BSC study where double stud wall moisture was evaluated with three different insulation strategies: 12" cellulose, 12" Open Cell spray foam, and 5.5" of Open Cell spray foam.

In Energy efficiency and durability | Asked By Lance Peters | Jan 12 18
17 Answers

Vinyl windows with synthetic stone

Hoping this isn’t a bad question.....any advice for detailing Synthetic Stone around vinyl windows (some have integrated J channel, some have brick mounding with integrated J channel).

In General questions | Asked By Birdie L | Jan 7 18
6 Answers

Will installing a 12 x 18 inch grille between floors help my forced air flow?

I live in a 1800 ft2 NYC brownstone duplex. The two floor forced air system is inadequate to say the least for the first floor. It is 20 degrees colder on that floor. I have had HVAC professionals in and they have told me that there are NO returns on the first floor at all. All the supply vents are in the ceiling and with 12 ft. ceilings, heated air doesn't descend (despite fans) adequately. One HVAC guy suggested punching a rectangular grill (18 x 12 or larger) through the ceiling of the living room into the dedicated air handler closet in the master bedroom of the second floor.

In GBA Pro help | Asked By Jcryder | Jan 15 18
33 Answers

120 year old uninsulated home siding retrofit

Hi all,

LP Smartside 76 series 8” 7/16” lap siding has been purchased by our contractor and now I am finalizing details.

Please review for compliance, efficiency and best practices and fill in my blanks. ;-) We plan to live here for a long long time and want to make sure we do it right.

Strip cedar shakes and old lap to 3/4" diagonal bracing or studs if bracing is rotten.
Replace rotten diagonal bracing with __?__.
Install tyvek as an air barrier
Install 1.5" R6 Roxul Comfortboard with 1x4 strapping screwed 1.5" into studs 16" OC

In Plans Review | Asked By bridgette downer | Jan 10 18
3 Answers

What do you think of the flex duct on this job?

We added some HVAC ducts to our basement's existing metal ducts as we plan to finish it. I have three questions about the Flex Duct they put in.
1.) Is flex duct ok to use in a basement like this?
2.) Is the way they installed the marked "A" okay? Looks a little sloppy to us how they tried to twist it into a bay, but what do you think?
3.) Are these both insulated? And, if not, should they be and is that something they can easily add?
Thanks in advance!

In General questions | Asked By Masb | Jan 16 18
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