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12 Answers

ERV and flex duct

We're planning to install a Renewaire EV90P ERV with dedicated ductwork in our new 1900 sq ft home. It's going to be a budgetary strain to install hard pipe for all the entire system. So I'm hoping we can get away with a rigid duct for a trunk (running parallel to floor trusses) and then 6 inch flex duct going out to the exhaust and supply registers (through the webs of the floor trusses) - this is what the HVAC contractor is recommending, but I'm concerned about this small unit being able to handle the additional resistance to air flow from the flex duct.

In Mechanicals | Asked By William Costello | Mar 22 17
6 Answers

Insulating floor of an old barn

I have an 1804 bank barn and plan to use the lower level as a shop. Since dirt falls through the floorboards above anytime I walk upstairs, I need to think about insulating as a first step.

The easy thing would be to spray open-cell foam on the ceiling (bottom of 1.5" floorboards); but, I'm concerned that the foam won't maintain an air seal when people and machinery move around upstairs.

In Energy efficiency and durability | Asked By Michael Stelts | Mar 22 17
1 Answer

Another Question over Spray foaming Cathedral Attic

Hi Martin.
Sharing more info and hoping for some suggestions. My cathedral vault cavities (drywall) in the attic only goes up about 2/3% the underside of the roof decking. The rest is open attic space where studs and roof decking exposed. See picture attached. Any suggestions on how to tackle this situation when spray foaming the attic?

In Green building techniques | Asked By uberaustin | Mar 24 17
22 Answers

Drainage plane between sheathing and rigid foam

I am working on an addition project located in Wisconsin. My plan was to use Huber Engineering Zip wall sheathing.

In reviewing Zip walls installation instructions, I noticed that Zip calls for a minimum eighth of an inch drainage plane between the rigid foam and the sheathing. In my wall section I planned to include a drainage plain (rain screen) on the outside of the 3 inches of rigid foam.

Will the recommended Zip wall drainage plane reduce the effectiveness of my foam insulation?

In Energy efficiency and durability | Asked By Jason Stringer | Jan 30 11
7 Answers

Spray foam attic with cathedral ceiling

I'm considering spray foaming my attic for energy efficiency and elimination of dust. The attic currently has blown in fiberglass insulation originally installed when the one-story house was built in 1993, which I plan to get vacuumed out prior to spray foaming. Last year I had a metal installed with synthetic underlayment on my A-frame roof. I have seven soffit vents on each side of my home. I also have a cathedral vault ceiling, which limits access in the attic. No ridge vents only a few 18"x 18"square style attic vents placed across the roof for attic ventilation.

In Green building techniques | Asked By uberaustin | Mar 22 17
23 Answers

Hydronic Heating System Hydraulic Buffer Tank vs Hydraulic Seperator

This question might be more appropriate in a plumbing forum but I have had such great and thoughtful responses in the GBA forums I look to here first. This is also a hydronic heating mainstream topic which should be appropriate for GBA.

In Mechanicals | Asked By Roger Smith | Feb 26 17
14 Answers

HVAC ducting - Climate Zone 7a

The house is 40 year old bungalow with heated basement. It has an older 80% efficiency forced air natural gas furnace with an input BTU/hr 88,000 and output BTU/hr 71,000 with 1400 CFM.

The living room is 268 sqft and is ~24% of the total volume of the main floor, which is open plan so it is connected to the dining room (268 srft) and kitchen (137 sqft), each being ~12% of tot vol, respectively. The living room is at grade level with 9.3' high ceilings, compared to the rest of the main floor that has 8' height ceilings and is ~2' above grade.

In Mechanicals | Asked By user-6759891 | Mar 19 17
7 Answers

Is there any reason to think XPS at the big box stores would be of a lesser quality than what is sold at lumber/supply houses?

I'm getting ready to demo and redo my basement and plan on air sealing the concrete wall, sills and band joist. I generally try not to purchase stuff from big box stores as I find their quality to be questionable. But if XPS is the same regardless of where it's sold than cost becomes the primary variable. That's where the big box stores do win out. Thanks.

In General questions | Asked By adam stanton | Mar 24 17
9 Answers

Building a house in Greenville, SC — insulation and air sealing questions

Building a house later this year. Plan to live in the home 30+ years. So I'm interested in the "long term."

The House: 3,350sf above grade. Very very little shade on this house. Kinda like building in the middle of a field. Lots of sunshine bearing down. Galvalume metal roof with 3/4" strapping between metal and synthetic felt (TBD). Zip System for exterior walls. 2x6 exterior walls. I'm planning on ponying up for the super efficient Trane XV20i heat pump. Cement fiber siding painted white.

The Plan:
Foam attic with open cell to 5.5-6".

In Green building techniques | Asked By Farm House | Mar 15 17
4 Answers

Closed-cell spray foam — Basement insulation concerns

Hi everyone, any insight you can provide is much appreciated.

I am currently preparing to install spray foam (4in of 2lb closed cell) in my basement.
The plan is to insulate the full basement walls (concrete + pony wall section), plus the sill plate and rim joist pockets.

A couple of questions/concerns I had prior to going ahead with the install..

In General questions | Asked By user-6803198 | Mar 23 17
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