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9 Answers

Double Stud Wall & Basement Insulation Review - Climate Zone 5A

I've read practically every article on this site and many others related to 2x4 double stud walls and moisture. I want to have a wall that is low risk for moisture issues without introducing any more expense and complexity than necessary. The following seems attainable with my budget, and doesn't seem to cause much builder concern for construction. From exterior to interior:

LP Smartside Siding
1/4 rainscreen composed of either a mesh or furring strips with an insect screen at the bottom
Tyvek Drainwrap
CDX Plywood, seams taped

In Energy efficiency and durability | Asked By Shane | Jun 15 18
1 Answer

Good advice for Florida homeowners with air conditioner problems

Curt Kinder is an HVAC contractor who understands building science principles -- and that type of HVAC contractor is, unfortunately, rare. Curt lives in Jacksonville, Florida, and he often posts comments on GBA.

Curt is helping to raise the bar on building science knowledge in his profession. He was recently interviewed by public radio station WJCT. If you want to hear some of his advice to Florida homeowners -- it's good advice -- visit this web site: Going Green.

In Mechanicals | Asked By Martin Holladay | Jun 15 18
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
1 Answer

Replacing R410a minisplit: Lineset cleaning, pressure testing, and purging

Should I use a cleaner designed for converting from R22 to R410a linesets to clean a lineset that will only replace a R410a mini split?

I am replacing a 7.5 year old Samsung 1 ton unit with a Fijitsu 1 ton unit. These are both single units. They both require 1/4" and 3/8" lines.

I've gotten mixed answers from many HVAC professionals on this question. It seems like the wild west here in Wisconsin on mini-splits (and other HVAC subjects).

In Mechanicals | Asked By Resilient_Kevin | 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
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