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19 Answers

Why is our home so inefficient?

We bought an 1,800 sq. foot house in the north Berkeley hills in November of last year. There was a small mold issue which we remediated in December and January. During that time we also did an extensive HVAC upgrade, with a 3-zone heating/cooling system, smaller/more efficient duct work, an in-line dehumidifier, and in-line air filter. (Our daughter is sensitive to mold and other airborne allergens, which is why we installed the dehumidifier and air filter.)

In Energy efficiency and durability | Asked By Chris Durand | May 22 16
8 Answers

What would a weighted average R-value be for a Superior Wall Xi?

I am trying to determine what the weighted average R-value of a Superior Wall XI and XI plus wall is. Does anyone know? I can post cross sectional diagrams if someone can tell me how.

In Green products and materials | Asked By Chaz Steffen | May 23 16
7 Answers

Fastening details - deck ledger to insulated slab

I am designing an insulated Monolithic Slab. I plan to install 4" of Roxul comfort board beneath and around the perimeter of the slab.

Does anyone have experience attaching a deck ledger to a slab (or stem wall) that is insulated with Roxul? Or is it advisable to place a higher density product beneath the ledger to avoid compression which may happen with the Roxul Comfortboard?

What type of fasteners are recommended for this application? Would a standard wedge type concrete fastener like a red head work?

Other solutions?

In Green building techniques | Asked By Michael Iacona | May 19 16
12 Answers

Flashing "innie" windows - tape, caulk, anything at all?

Hi everybody! My builder friend and I are uncertain whether or not we are making mountains out of molehills here, and were hoping to get some feedback on a flashing detail.

This project has a thick wall buildout and "innie" windows: the nailing flange of each window is on the same plane as the house wrap, with exterior insulation and strapping/siding on top of that.

In General questions | Asked By Benjamin Wooten | May 9 16
1 Answer

Floating slab with frost walls — Plumbing and floor framing

We are doing a relatively large expansion. of a small studio space. A much earlier constructed garage/shed to which the studio space was added on to has been removed. We are using an insulated pad with frostwalls. The expansion will include all plumbing. Due to unavailability of a plumber and concerns over the lack of flexibility of cast in place plumbing, we have decided to frame the 4 x 12 foot portion of the pad.

In Green building techniques | Asked By Potter Shaw | May 23 16
11 Answers

Paint choices


In General questions | Asked By Lucyna de Barbaro | Mar 5 16
7 Answers

What is the best airtight LED retrofit for can lights?

I couldn't talk the builder out of can lights on the top floor, so I thought I could fix the problem once he's all done.

In Green products and materials | Asked By Kevin Dickson | May 20 16
6 Answers

Installing LP Smartside over 3" foam

Question: I am putting an addition on my house and have a question about fastening the LP Smartside.

My wall details are as follows (from inside to outside).
* 5/8" sheetrock
* 3/4" plywood
* 2x6 wall with r-19 or 21 fiberglass insulation
* 3" foam
* Furring strips, probably 2x4 - has to be at least 1 1/2 thick per LP
* LP Smartside

In Green building techniques | Asked By brett mattson | May 19 16
15 Answers

How to vent a flat roof

Designing a home in Santa Fe, NM. Roof will be TPO over open web trusses. Pitch is 1/4" / ft.
Parapets all around. Insulation will be blown-in cellulose. R value to be 50. How do I vent the roof cavity above the insulation? I could use mushroom caps. I've done the calculations and I need quite a few. How much air space is required above the insulation? 2", 3" or more? Also planning on installing a radiant barrier between the tops of the trusses and the sheathing. When I build crickets over the sheathing will I need to provide air ventilation for the cavity? Thanks!

In General questions | Asked By jack robinson | May 14 16
1 Answer

Efficient house build blogs that I'm not following?

Hi all,

Besides the houses blogged about here at Green Building Advisor, what other house build blogs can you recommend? Particularly interesting in blogs about pursuing net zero, superinsulation, energy-efficient remodels, and all the passivhaus/passive house stuff.

Thanks in advance!

In General questions | Asked By Matt Gauger | May 21 16
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