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4 Answers

How should I deal with attic insulation where roof meets wall?

I'll be blowing cellulose into a vented 1920's attic in Oakland Ca. zone 3c. Roof has no overhang, rafters begin on top plate. There's also a small daylight gap where top of gutter board and bottom of roof sheathing meet. Would filling that intersection and contacting roof sheathing and rafters be a concern?



In General questions | Asked By carl haberberger | Jun 1 16
4 Answers

Ways to graph air conditioning run times?

I'd like to be able to graph and visually see the cycling pattern of my traditional split system heat pump here in Central Florida. The thought is that if I can determine that it is off, say, 25% of the time in the afternoon on the hottest summer days, that I could probably downsize the tonnage by 25% when it comes time for replacement. Of course, I would want to make sure that my system was properly charged and operating before conducting such a test.

In Mechanicals | Asked By david jensen | Jun 1 16
3 Answers

Could plastic attic ventilation baffles on a 5/12 roof create a moisture problem?

The article on attic ventilation baffles notes two pretty good commercial products, Accuvent and Smart Baffle. Both are made of plastic, with essentially zero vapor permeability. With a steep pitch roof, that's fine. Any vapor that come up through the ceiling, through a leak or through vapor diffusion through the drywall, can keep going up through the insulation and reach the vent space above the insulation, so there's no moisture trap.

In Green building techniques | Asked By Charlie Sullivan | May 31 16
3 Answers

Insulating walk-out basement

I'm insulating a walk-out basement in a new construction. The house is of a double wall design, and will be filled with dense pack cellulose. I understand that for the foundation walls that I can not apply cellulose directly, however I had thought that if I apply a layer of closed-cell either sprayed or laid in in sheets then I should be able to fill the rest of the cavity with cellulose, assuming that there is no concrete exposed. My question is how many inches do I need to use to assure I have no problems with the cellulose?

In Green building techniques | Asked By Geoff Frood | May 29 16
1 Answer

Window flashing when using SPF instead of rigid foam

The retrofit I'm planning will add exterior insulation in the form of SPF. Will add vertical furring strips suspended 1" or more from the existing siding/sheathing for mounting the new siding. For windows, will use the window buck approach and 'outie' window mounting style unless another style has advantages for ease of installation, durability etc. 'outie' would match the existing appearance, could change for the right reason.

In General questions | Asked By TIM LANGE | May 31 16
7 Answers

ROI and incremental costs

The topic of ROI seems to permeate a lot of the discussions of both building envelopes and heating components. I wonder if the way we look at it really takes into account the realities of the way the North American building industry works?

Unlike most of the projects here on GBA which are either custom or owner-built, the overwhelming majority of house construction is speculative - that is financed and built by developers with no input from the eventual owners.

In General questions | Asked By Malcolm Taylor | May 30 16
6 Answers

Log home DER Ideas?

I am a long time reader of GBA and, as a result, would not generally even go near a log house if I was interested in energy efficiency. That said, I find myself considering one due to its location, location, location. Given that, I would like to get some opinions about the best ways to go about retrofitting the house so it is at least reasonably energy efficient. Cost counts, so 'tear it down' options aren't all that helpful to me.

In Energy efficiency and durability | Asked By Rob Shuman | May 31 16
4 Answers

Is R-1 fan-fold insulation cost-effective as vinyl siding underlayment?

I am installing vinyl siding on a home in Pittsburgh PA as part of a HUD financed project. As such, HUD has supplied the specs. The requirement is for R1 fanfold followed by Tyvec. I think that the principal function of fan fold has traditionally, pre-house wrap, been to limit air infiltration (not provide R value), a function that is in this case served, redundantly, by the by the Tyvec.
There is almost no wall insulation and no plans to install any soon but there is adequate attic floor insulation.

In Energy efficiency and durability | Asked By Thomas Rydle | May 29 16
2 Answers

Retrofitting insulation: heat loss/gain where ceiling meets the wall

Hello all,

As part of my efforts to air seal and insulate my home, I just purchased a new FLIR infrared camera. First, what a cool tool for an energy nerd! It has instantly identified areas of the home on which to focus.

In Green building techniques | Asked By Brian Gray | May 31 16
31 Answers

Exterior rigid foam and re-siding project

I'm seeking input and opinion. I'm looking to re-side with the dread vinyl (need the low maintenance for my two story house). My 40 year old post and bean house has interior sheetrock, 3.5" of fiberglass batt insulation with kraft paper, rough cut full 2x4 studs on 24" centers, plywood sheathing (I think 5/8"), paper (a mix of Tyvek and felt), and cedar shingles. Shingles and paper will of course be removed, sheathing inspected in the process. I'm in zone 6.

In Energy efficiency and durability | Asked By Howard Gentler | May 2 16
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