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1 Answer

No rainscreen gap in an all-cementitious wall?

Some of you who have read my previous posts know that I'm exploring various alternative wall assemblies for a net zero (Living Building Challenge) home. Attached I show a proposed detail of the 1st and 2nd floor walls. I am interested in whether the 1st floor AAC --> Roxul --> Cement Board (w/ stucco finish) is robust without a rain screen gap?

Asked By Ethan T ; Climate Zone 5A ; ~6000HDD | Sep 25 17
11 Answers

Low-slope roof

I am building a PGH and I have a 32' run of unvented, low-slope roof that we will start framing out shortly. The interior stack-up is gypsum, 2x3 service cavity, Siga Majrex air and vapor control layer (let's vapor out of the cavity, but not in), 2x12 joists, dense pack cellulose between joists, 3/4" Advantech seams taped with Wigluv. I was planning on using a unvented nailbase product that has 4.5" of polyiso with a layer 1/2" osb attached to the top. I am in Zone 4 and this will provide more than the required .31% of exterior to total r-value even if I de-rate the polyiso r-value to 5.

Asked By Jonathan Lawrence CZ 4A New Jersey | Aug 18 17
1 Answer

Where to exhaust bathroom fans?

My preference would be to exhaust my bathroom fans directly through the exterior wall, to keep the ductwork very short, with the warm, moist air kept inside a conditioned space until exhausted outside. But the outside vent might be only 18" or so below my soffit vents, and I'm concerned the moist air may be sucked up into the attic and condense under the roof. Is that a realistic concern?

Asked By Debra | Sep 25 17
2 Answers

Solutions for exterior insulation on home with poly warm-in-winter side?

I love this site!

Home is in 4C or 5 (Clackamas County Oregon - DoE shows 5 on map, but lists marine 4 on county by county) and of mid 90s construction.

Asked By user-6924093 | Sep 24 17
2 Answers

ICF home and ventilation

We built our 2300 sq ft home last year and moved in January of this year. We have a heat pump air conditioner and I have the fan set with my Nest thermostat to go on every hour. We also have a dehumidifier going. Despite this our humidity level in the house is 45-50%. We don't see condensation in any of the windows. We are worried about the possibility of mold and poor indoor air quality. What are your recommendations?

Asked By melsie | Sep 24 17
6 Answers

Subfloor for new covered 3 season porch?

I am planning a new 12'x12' 3 season covered porch attached to the house in far northern Minnesota. The footings are pinned to solid ledge rock, so there is no chance of this thing moving. I'm using pressure treated ledger and 2x10s joists.

The porch will be about 4' above the grade. The underneath of the structure will be protected from critters by heavy screening and a trellis. However, it will be exposed to outside air movement and temperature and humidity swings.

Asked By Steve Lenertz | Sep 23 17
1 Answer

Post & Beam Sealing

I have been doing a lot of reading on this site and other places around the internet. It feels like my head is about to explode so I'm just going to ask the question. Most homes that I've seen talked about that have a crawlspace also have a perimeter wall of cinder blocks or something like that. Mine does not. There are 5 rows of 13 posts per row. I will try and post the pics showing this. To do a liner I would have to run it down 4 different rows and then splice it all together with tape and hope that it totally seals it off.

Asked By Five20too | Sep 24 17
1 Answer

Solenoid valve for the toilet hookup?

Dear Martin, et al:

Having just changed the flapper valve in a toilet after my water bill was high due to the unappreciated running of the commode, I am wondering why we don't have a better system for toilets? Specifically, why not a valve such as one finds in a lawn irrigation system?

Asked By Brian Lengel | Sep 24 17
4 Answers

Closed or open cell foam?

Is Great Stuff (in the can from Lowe's or Home Depot) open or closed cell foam? A google search said closed cell but I recall a GBA article on adding water vapor increases it's expansion during curing so that implies open cell, doesn't it? Thanks. (brand new to GBA subscription). Brian Lengel, Austin, TX

Asked By Brian Lengel | Jan 3 16
15 Answers

Am I asking for trouble?

I may need to switch to a 2x6 load bearing exterior wall as my outer wall cannot be load bearing but had to be changed to a "Larsen" like truss. To maintain about the same total wall depth I'm considering an inner 2x6 load bearing wall sheathed on the exterior with OSB and filled with mineral wool r23 and a modified Larsen truss 2x6 wall outside. I'm envisioning the trusses as frames of 1x2 with pieces of Thermoply on one side at both ends and filled with mineral wool (about r19). Should I stagger the studs? or put them inline?

Asked By Jerry Liebler | Sep 21 17
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