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5 Answers

Attic and roof stack

Does this seem like it will work? Austin TX, Climate Zone 2A.

From inside to outside. Air barrier at the interior ceilings.

Drywall (or lath and plaster ceilings)
Blown-in Cellulose (~16 inches, but less over outside walls, as no raised heels)
Mostly solid wood board sheathing (from 1950s), one area of low slope plywood (~1.5 in 12).
Solitex Mento as roof WRB (or other vapor open WRB)
Counter-battens (1x material criss crossed)
Metal roofing

In Plans Review | Asked By James Howison | Jun 14 18
3 Answers

Thermal break for in-betweenie window box?

Hi, Peter in zone 5 (Boston), considering a PGH design with double stud walls (2x3's inboard, 2x4's outboard; 2.0 SPF at the outside wall and cellulose for the remainder) with about 10" of insulation space (shooting for R-40). (See case 10 of Bldg America report BA-0903: https://buildingscience.com/documents/bareports/ba-0903-building-america...).

In Energy efficiency and durability | Asked By Peter Staecker | Jun 14 18
4 Answers

Securing wall sheathing

I have two questions about securing plywood wall sheathing:

1) Many local contractors are now using staples to secure sheathing instead of nails. I never heard of that. I realize that it can meet local code, if properly installed, but will it do an adequate job of earthquake resistance in seismic zone C? (moderate risk) We also occasionally get high winds or tornadoes.

In General questions | Asked By Debra | Jun 14 18
3 Answers

To caulk or not, above a 1925 redwood window head jamb?

I was just pulling out the caulk gun, when I noticed this head jamb is tapered.

The house is 1925 stucco in USDA zone 10b (San Francisco Bay Area). So did the original builders intend this as a form of weep? Instead of caulk is it actually better to leave the edge open, or cut a weep into the caulk?

The stucco wall in question is settling, and has various patched cracks. So, in theory at least, water may weep down the old tar paper behind the stucco, during the rainy season. The walls are at least partially filled with cellulose, which reduces drying to the interior lathe and plaster.

In General questions | Asked By Bryce Nesbitt | Jun 11 18
22 Answers

Closed-cell foam thickness vs. R-value

We are in the Asheville area in the mountains of Western North Carolina (Zone 4A) where I am renovating a small 300 sq ft shed roofed cottage. I intend to use closed cell foam in the roof, walls, and floor. I want a well insulated tight envelope as we are going to try to heat with an electric space heater.

I have now had two different contractors recommending only 3" of foam in the roof (R-18-21) and tell me I don't have to worry too much about the R values, as there is a steep diminishing return curve after 3". Is this correct? Should I insist on 5 or 6"?

In Energy efficiency and durability | Asked By Ross Williams | Jun 11 18
9 Answers

Roxul ComfortBoard installation with siding

We are using 2x6 construction with zip system, 2" of roxul, furring strips and siding. My question is what to do with the extra 2.5" cavity that this will create at the bottom. Is the best practice to move the walls in, install a pest scree, etc? Thanks

In General questions | Asked By User-7088022 | Jun 12 18
6 Answers

Fentrim tape worth the expense?

Can anyone weigh in on this super tape? My client is balking at $2k in tape, vs $400 for grace vycor. We have euro windows with no built in flashing.

In Energy efficiency and durability | Asked By Lukas Schwartz | Jun 12 18
1 Answer

Installing fiberglass batts in attic

I have recently finished up air-sealing my unfinished attic, and am going to be installing R30 faced fiberglass batts in between the joists. My question is in regards to how aggressively should I be pressing down on the batts when I install them? Do I need to really push down on them to make sure that the vapor barrier on the batt is pressed closely to the attic "floor" made up of drywall?

In Energy efficiency and durability | Asked By DrJimesTooperMD | Jun 13 18
32 Answers

How to seal ventilation baffles in rafter bays?

If I use the "Smartbaffle" in my rafter bays, I would tape across the joints where two baffles meet, but do I need to seal the edges against the rafters also? What would be the recommended/cost effective way? Tape, caulk (messy), spray foam cans like great stuff (would add up with 54 or so 25ft long rafter bays from soffitt to ridge.


In Energy efficiency and durability | Asked By Joe Watson | Aug 5 15
2 Answers

Insulation and air sealing on attic side of bonus room

I live in southeastern NC in zone 3. I have a bonus room above my garage. The room does not have typical knee-walls. The pitch of the A-frame was raised to pull most of it out of the room. What I have now is a bonus room that is essentially a normal room with a nearly 8' ceiling. when the house was built, batts were installed in the stud cavities of the bonus room but were not enclosed on the attic side. So I have batts that are open to the attic with no air barrier of any kind. My understanding is that this is not ideal and the batts should be enclosed on all six sides.

In Energy efficiency and durability | Asked By Jason Dennis | Jun 13 18
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