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34 Answers

Rock wool insulation advice?

I'm building a house for my wife and myself and I'm about to start insulation using mineral wool. Exterior walls are 2 X 4 studs w/ tyvek house wrap, 2" polyiso, 1 X 4 vertical firring strip and d 1 X 8 T&G clear cedar installed horizontally. Roof is 1/2" on 12" epdm with 4 1/2" polyiso on 2/4" plywood over 2" X 12" ceiling joists/rafters. I'm using R30 7" Roxual bats in ceiling cavity. My question is should I hold the bats tight to the roof sheathing or down tight to sheetrock? Walls are getting R15. we are in zone 6.

In General questions | Asked By Ben Williams | Dec 20 15
2 Answers

Manual J, layup selection and HVAC recommendations

I am looking at building a home in NW Arkansas and hoping to bounce some ideas off the group here. We are still a ways away but trying to look at options based on what I’ve learned reading hundreds of pages here.

NW AR is CZ 4 but the AR code treats the insulation requirements as CZ3 – R30 roofs and R13 walls. My plan is to build to 2012 CZ4 standards as a PGH. I’m thinking to use 2x4 with cellulose fill covered by 1½” ZipR sheathing. R50 cellulose in vented attic. Double pane .30 windows or better. Does this make sense for the climate?

In Energy efficiency and durability | Asked By Tim Koelker | Jan 22 16
8 Answers

What complexities exist in building a racquetball court under the garage?

What additional design details might be requires to go from more typical 9 foot basement wall to 20?
Location: Southern Maine
SIZE: 20X40X20'

However, Some things I had though about were:

helical tiebacks-to keep wall from bowing
An air exchanger-to keep good oxygen levels
A sump pump to prevent it from becoming a pool
Soils test to see if rock/granite was present at planned excavation site

If anyone could point me to a source for construction design details that would be terrific.

In Plans Review | Asked By Hal Sartelle | Jan 22 16
6 Answers

What manufacturer makes the best recipe for a cement-based siding for a New England green home?

Is the wood content of fiber cement siding a good thing? What's its purpose?

Has the recipe for cementicious siding changed from what was used 50+ years ago?

Sometimes I see older cementicious siding shingles cracked and broken. Is this just as likely in time with the new stuff?

Woodtone RusticSeries adds composite to theirs. So you get wood, cement and composite in one product. Unfortunatly the 15yr warranty doesn't lend much confidence to the product.

In Green products and materials | Asked By Hal Sartelle | Jan 23 16
8 Answers

Squat toilet: Alternative minimalist design?

The squatting position is thought by many to important benefits over what we might consider a modern civilized toilet to be.

Are squat toilets now code approved in the US?

If so,they are in my Western eye unsightly and create an undesirable contour in the floor. That said is there a way to help make sure this flap drain doesn't clog if one daily toes a duty down the lifted grated drain during a 15-20 gallon shower? Is there a way to purpose the shower water into a flush? for the drain?

In Building Code Questions | Asked By Hal Sartelle | Jan 22 16
7 Answers

Installing solar panels over rigid foam insulation

We are about to break ground on a pretty good house in Virginia (Zone 4). The attic will be included in the conditioned area for upstairs bedrooms, so we will be building an unvented roof. Roof insulation is planned as Roxul ComfortBatts inside and ~R20 in two layers of rigid foam outside, topped with OSB (Hunter nailbase panels).

All that sounded great until I considered putting solar panels on the roof. Fastening to the roof trusses through 3"-4" of foam seems like a hit-or-miss proposition.

Do any of you clever folks out there have advice? Thanks in advance!

In Green building techniques | Asked By Esther Streusand | Jan 23 16
3 Answers

Sealing gaps in fieldstone foundation

I have a 1900 colonial home in MA with a fieldstone/rubble foundation.

While air sealing recently, I discovered one area of the basement near the basement door, which has a 1/2-1" by 4 ft gap where the mortar has crumbled away over the years. Is there anything I can do temporarily to seal this up until I am able to repoint this come spring/summer?

I could spray foam it, but it would probably be a huge headache to remove the foam when it comes time to repoint the stone. Would backing rods and caulk be a better option?

In General questions | Asked By David Schrier | Jan 23 16
6 Answers

Condensation under WRB during construction

Built a 2 story, 1300 SF addition on a house in Portland OR which got dried in in early December. The addition has no insulation yet and heat is inadequate and inconsistent via wood stove and the central natural gas furnace that serves only the first floor. The stairwell to the second floor is centrally located and the wood stove is on the first floor adjacent to the stairwell opening. Second floor heating will be a yet to be installed mini split system. A portion of the addition is an unheated garage. Currently running multiple fans and 2 dehumidifiers day and night.

In General questions | Asked By Robert McKee | Jan 23 16
7 Answers

Design for sealing open dirt floor crawl space

Hi I have a 28' x 30' crawl space that has a dirt floor and CMU walls. Ceiling of it is exposed with pipes and wires running around everywhere. I live in western Colorado so it's dry most of the year. I get some ground dampness, but no flooding, during a few months of summer when my hillside gets saturated in places from a natural spring in the rock ridge above me. I have pipes outside of the crawlspace that provide drainage and I keep the soil sloped away from the home walls. My adjacent slab walkout basement has 4" gravel, 2" sand, and vapor barrier under the slab.

In Energy efficiency and durability | Asked By Andy Nels | Jan 21 16
1 Answer

Panasonic WhisperComfort ERV - not necessarily a "spot" ERV anymore!

Corbett Lunsford just posted the first of a series of videos on how to convert a Panasonic WhisperComfort "spot" ERV into a ducted ERV. Apparently this setup was described to him by Panasonic engineers, so it has some legitimacy behind it.


This video doesn't contain all of the details, but more videos will follow (you can subscribe and get notified), and this is such a unique modification for a uniquely affordable ERV that I thought it was worth pointing out.

In Green products and materials | Asked By Nick Welch | Jan 22 16
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