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7 Answers

Proper installation of 2 adjacent outdoor mini-split units?

We just finished a major renovation project that included sprayfoaming, all new windows, and one new Fujitsu Halcyon mini-split on each of the three levels. The temps are now dropping here in Maine, so we're finally getting a chance to experience the heating capabilities after a ton of research I did on this site and others (we do have backup electric heated floors and a propane fireplace ducted to the lower and upper levels as supplemental heat sources for brutally cold times).

In GBA Pro help | Asked By Phil Knutel | Dec 6 14
11 Answers

Vapor permeability of polyiso

Attached is a picture of foil-faced polyiso which as a bunch of holes in it. The holes were made with a wall paper removal tool which puts holes in the paper to allow liquid stripper to get behind the paper. I welcome comments on this approach to see of foil faced polyiso could be modified to allow vapor permeability thru the sheet if holes were done on both sides.

In Green products and materials | Asked By Dirk Gently | Mar 18 14
8 Answers

Span tables for dead loads above 20 PSF.

Does anyone know where I can find span tables or equations to calculate dead loads in excess of 20 PSF?

Every table I've found including IRC, AF & PA show dead loads of only 10 or 20 PSF. I'm looking to see my options for a pour over a subfloor I'm designing for an addition. I do plan on having a Structural Engineer double check my math and stamp the drawings, I just would prefer not to pay them and extra $500-600 to pretend like it took them all day to do a set of calculations for the floor joist, girder, and columns.

Thanks for any help in advance!

In Building Code Questions | Asked By Michael McArdle | Dec 6 14
6 Answers

Insulating a pier foundation floor in a marine climate

What's the best practice floor insulation assembly for a structure built on a very low pier foundation in a cold and wet marine climate?

I'm rebuilding a very small, very poorly-built, addition in south coastal BC (Canada). The addition rotted out, in part due to poorly managed roof runoff.

The climate here is damp year-round, with 50%-100% humidity. Temperatures go much above 60 F for eight months of the year. Winter means nine feet of rain with temperatures in the 40s (F) while summer means a few weeks of temperatures in the upper 70s (F).

In Energy efficiency and durability | Asked By Joe Smith | Dec 4 14
3 Answers

Plywood in the framing exposed to the elements for ~5-6 weeks?

Our new construction is in Pittsburgh, PA, mixed humid climate, quite rainy. We also usually have sleet and some snow in winters. The framing is to start 12/8/14. Windows and EIFS systems won't be installed until about mid-January or possibly later. Do we need to wrap the house in the Tyvek for the period before EIFS system can be applied? We thought of pre-treating plywood with liquid-applied weather barrier used in EIFS, but that can only happen at 40F and above and we won't have scaffolding/tenting until mid-January. The estimated cost for Tyvek is $800.

In General questions | Asked By Lucyna de Barbaro | Dec 6 14
1 Answer

Flash-and-fill hybrid plus external insulation?

I designed a 2x6 dense-packed cellulose wall, fully sheathed in plywood, plus 3" of external Roxul Cavity Board. Climate Zone 6.

I'm trying to consider alternative wall types due to the added labor costs of external insulation, specifically the complications with fastening and window detailing when getting upwards of 3".

I'm trying to wrap my head around the Flash and Fill system described by Building Science Corp.

In Energy efficiency and durability | Asked By Meri Lewis | Dec 6 14
18 Answers

Exhausted By a House That Saves Energy


An article in the New York Times about a couple who built a very large net-zero house in Vermont, and are now regretting building too large and too complicated.

In General questions | Asked By Jack Woolfe | Dec 4 14
4 Answers

I need help on building some DIY solar projects (portable)

I have done a lot of research and visited many sites but still cannot figure out a few things with a portable solar charging project that I'm working on... I need help with figuring out a solar design to charge say my phone. Is it possible to hookup a wall charger to the output part and it wiil do all the work? Also I'm including batteries and Need to know how to set it up so that the phone will be powered by the panels and battery and the charge will be there only when I plug in the phone... No wasted energy.
So here's all of my knowledge from research:

In General questions | Asked By Shaye Miller | Dec 5 14
27 Answers

Options for garage heat

I would like opinions regarding options for heating a garage. I know, I know, "Why the H@!! are you heating a garage?" will come to mind for many of you. Others will agree that it saves on car repair costs, improves longevity, and allows for storage of "perishables" such as paint cans, bulk canned garden vegetables, and other things wife understandably does not want in house.

Here are the pertinent factors shaping the decision:
* Super-insulated house, Manual J heat load calc gives 12,400 BTU/h (3.6 kW) peak heating requirement (for garage alone)

In Mechanicals | Asked By Kent Jeffery | Nov 20 14
3 Answers

Rigid foam crawlspace insulation — vapor permeance?

We currently have an 18x30 crawlspace that is vented with batt insulation in the floor joists. The crawlspace also connects to a full basement that is 22x30. There is a 2'x2' opening between the crawlspace and the basement that is blocked with plywood, plus a few openings for ductwork and such. There is a radon mitigation system installed on the crawlspace floor, plastic covering that goes up about 10" on the crawlspace walls. HVAC supply and returns, plus plumbing all goes through the crawlspace to that section of the house.

In General questions | Asked By HD S | Dec 4 14
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