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6 Answers

Best insulation and sealing for a tucked-under-garage ceiling?

We are purchasing a circa 1966 Cape in the Philadelphia are with the garage tucked under the master and guest bedrooms and two baths. The garage ceiling is currently covered with Homasote, but there are small areas where we can see an underlying plaster ceiling with missing chunks. The joists are 2x10s and there appears to be some fiberglass insulation batts in place.The HVAC ducts run below the joists and are mostly covered in Homasote, but several feet of ducts near the overhead door opening are exposed and uninsulated, but with remnants of asbestos.

In GBA Pro help | Asked By Geoffrey Simon | Jul 17 17
3 Answers


I thought I had a GC/Framer lined up to build a 16" double stud wall but they have backed off. I found a builder willing to get <3ACH, code in NYS is 3 ACH@50, but not double stud, only 2x6 and he wants to use spray foam. Being PHPP only list kBTU/(ft²yr), how do we convert that to MAX BTU/Hr?

Is this the correct conversion for average BTU/Hr?

([PHPP kBTU/(ft²yr)] * 1000 * [square ft]) / 365 days / 24 Hr = average BTU/Hr

In PassivHaus | Asked By Jeff Ziegler | Jul 19 17
3 Answers

Specifying or noting "Mooney" x-hatching on ext. walls

The contractor who is building the dried-in shell for my house gave me the green light to add the "Mooney"-like cross-hatching to the exterior walls. The building department wants to see the x-hatch on the plans that I submit.
I'm showing the ext. walls 1½" thicker but I don't know the right ways to note the x-hatching.
Could someone attach a couple examples or describe the appropriate note?
Does someone have a detail drawing they have used before?

In Plans Review | Asked By Mark Walker | Jul 18 17
6 Answers

Thermostats and weather compensation in a well insulated tight house

Trying to figure out a heating strategy for the following house:
- climate zone equivalent to 4A (continental Croatia, Europe)
- 170m2 net, ground floor + 1st floor
- ~35kwh/m2 a, so well insulated
- Zehnder ERV
- underfloor radiant heating + gas boiler (also used for warm water tank)

I am trying to figure out two things:
- do I need thermostats in several rooms?
- do I need weather compensation thermometers and a regulation system that supports it (most do)

In Mechanicals | Asked By davor radman | Jul 18 17
3 Answers

Cantilevered decks - solve moisture problems on previously-installed ones?

We have a small cantilevered deck off our 2nd floor bedroom, where the deck's support members extend through the building envelope with no supports below. I recognize this is a less than ideal structure, but it was installed by the previous home owner 11 years ago.

We've noticed signs of moisture intrusion on the interior living space (to be expected with this deck set up).

In General questions | Asked By hankla.lzo | Jul 18 17
10 Answers

Triple-pane windows for a high-efficiency cabin

1400sq. Ft. cabin...Zone 7 10,000 HDD with R40 walls and R80 in roof. Looking for ideas for windows. I'm probably looking at a manufacturer in North America for costs and timeline to get.
Have looked at H-Windows, in person and several others online, including Marvin "Tripane".

Any pluses or minuses with any of them would be helpful.


In Energy efficiency and durability | Asked By Steve Lenertz | May 29 17
3 Answers

Insulated metal roof panels

Hi to everyone,

I am in the planning phase of a residential home in Paraguay/South America. Climate ist hot humid subtropical maybe like New Orleans or Florida.

A real problem down here are the roofing options. Right Now I am down to a metal roof over an unvented unconditioned attic or over a vented attic.

One of the more modern appoaches in this country would be the use of insulated metal roof panels, similiar to this ones:

In General questions | Asked By user-6885983 | Jul 17 17
1 Answer

Should I use EPS/XPS or spray foam to insulate basement walls with a brick texture?

I am looking to add a few bedrooms and a bathroom to my walkout basement. It has poured concrete walls on 3 sides, but the poured concrete has a brick pattern / texture to it complete with simulated mortar joints. Since this is an uneven surface, I am wondering if EPS/XPS is an option or if I have to go with spray foam insulation to fill all the voids?

In Energy efficiency and durability | Asked By Macrocks | Jul 18 17
20 Answers

Tankless, tanked, or both?

I'm in the process of trying to figure out what i'm going to do for hot water on a new custom home I just broke ground on. I don't want to say money's not an object but it's definitely not my first consideration.

A colleague of mine recommended that I explore doing a tankless gas water heater with a 10 gallon standby tank. In exploring this option I came across a Rinnai RH180 hybrid tank-tankless water heater.

Does anyone have any experience or thought about this unit...good, bath or otherwise? Thanks!

In Mechanicals | Asked By Michael Winn | Jul 7 17
24 Answers

Rainscreens with Roxul Comfortboard IS?

Hi all.
I am planning out my wall construction for a home in zone 6. Not much rain (15" annually), but plenty of snow in winter (56" annually). Hot (and mostly dry) in summer (80sF to low 100s), cold in winter (mostly lows in the single digits, but sometimes minus teens F). My house will not have much direct sun due to northern exposure and tree shading.

All that said, here is the wall I am considering:
- wall board
- 2x6 fir studs on 16" centers, Roxul Comfortbatt (R23) between the studs
- OSB, taped and sealed for my air barrier
- house wrap for vapor barrier

In Green building techniques | Asked By Mike B | Mar 20 16
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