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7 Answers

Slab insulation using EPS


I am in the process of designing a new home construction project. Naturally, I am interested in minimizing costs and maximizing insulation/efficiency. The home is slated to be a ranch-style that is slab-on-grade. I have been planning on using high-density EPS foam (6" thickness) underneath the slab, and 6" foam on the exterior of the slab and footings. The EPS foam would also go underneath the footing as well so that there is a continuous layer of insulation.

In Green building techniques | Asked By Chris Barnes | Oct 15 13
25 Answers

PassivHaus backyard workshop

We're looking to build two sheds in our backyard. One is for storage of lawn-mowers etc and doesn't need to be insulated. The 2nd will be a workshop in which we will probably spend a reasonable amount of time. We're keen to do this as a sustainable showpiece highlighting various aspects of sustainability. We have thought of doing it as a PassivHaus project. As far as I know there are no complete, stand-alone PassivHaus buildings in Australia so this might be a useful demonstration site. A few things come to mind that perhaps some GBA folks could comment on.

In PassivHaus | Asked By David Coote | Nov 14 12
17 Answers

Ductless minisplits

I really like the idea of using ductless mini-splits in our new home for heating and cooling. Before I get too excited and start getting quotes, I was hoping for some opinions and feedback from those that have experience with these systems. I know it is a difficult question without knowing our heat load (Manual J in process), but any thoughts of whether it may work in our house are appreciated.

Zone 5 - Detroit, MI
2,400 SF (2 levels) + 1,200 SF basement
2x6 wall w/ cellulose + 1.5" polyiso (r-10) on exterior
R-10 under slab
R-20 basement wall
R-75 vented roof

In Mechanicals | Asked By Troy Stevenson | Oct 2 13
3 Answers

Is this an airtight duct?

I have a supply and exhaust line roughed in for an upstairs ERV. These lines are running in an unvented attic space.

So the contractor taped the joints but not the seams. Do you need to tape and/or mastic the seams to properly seal these types of lines?

In Green building techniques | Asked By Steven Knapp | Oct 5 13
3 Answers

Foam Insulation Option with Internal Poly Vapor Barrier?

My existing home has 2x4 exterior walls with a polyethylene sheet installed in front of the studs and behind the drywall. The walls are insulated with faced batt insulation The exterior sheathing is brown fiberboard. House was built in 1977.

I searched this site, but can't find any acceptable recommendations for insulating with exterior foam panels. I've read all the articles about the bad things that can happen when moisture is sealed between an internal and external barrier?

Are there any options to add external insulation? Am I just out if luck?


In Green building techniques | Asked By Chris Jones | Oct 15 13
3 Answers

Cupping floorboards

I've been working on a house in New Orleans off and on for 5 yrs., and just recently my client informed me that all the floor boards from the front of the house to roughly 10 ' back are cupping across the whole front of the house.

It' s a raised (4') home built in 1830.There is batt insulation underneath held in by chicken wire, with about a 1" gap between the insulation & the floor. No subfloor. There is no water intrusion from any other source. The batts are bone dry.

In General questions | Asked By roger steinbrink | Oct 15 13
1 Answer

Could your small channels be used to carry a ceiling fan wire to a wall (masonry ceiling)?

We are moving into a retirement complex with concrete between the floors. They charge $300 for putting the fan wiring into some type of channel instead of merely hanging the wire and chain across which is free.. Was wondering if I could use your small channels to put across the ceiling and down the wall to an outlet myself. Could the channels be glued onto the ceiling and wall?

In General questions | Asked By DAVID LAUTNER | Oct 15 13
3 Answers

Ladder rafters, fly rafter, look-outs

Whatever name you prefer, I have a question on how far they are allowed to extend out vs how far they extend back into the attic. I am of the understanding that the ratio is 1:1. A "normal" gable end stick-out is often 2', so the first truss, to which said ladder rafters abutt, should be inset 2' from the gable truss. It is my understanding that this "balance" will prevent lifting of the first truss if, say, the ladder rafters instead stuck out 4' and back in only 2'. (Gable truss is the fulcrum.) If 1:1 is the recommended ratio, how far can you push that if you assume a 30-40 psf snow load?

In Mechanicals | Asked By John Klingel | Oct 15 13
7 Answers

Spray-foam home — ventilation?

I hope you can help. I'm in a less-than-a-year-old, production-built, spray-foamed, tight, energy-efficient, 2-story home outside Orlando, Florida, 1,758 square feet, which developed "sewer"-type odors on the first floor.

The builders solution so far has been to install an inline "booster" fan to the fresh air intake on the AC system to meet ASHRAE 62.2. But now, understandably here in Florida, indoor humidity has risen dramatically.

In Green building techniques | Asked By mark sokolowski | Oct 15 13
4 Answers

Energy efficient windows/doors

We will be in the starting to build our energy efficient home in the next few months. We've been talking with Intus, Klearwall and Hoco to see which window/doors would be the best for us. Is there a good American window (triple pane) that we should also be considering? Which one of these manufactures..... Jeld-wen, Marvin or Pella would give us the best quality in windows.

Thanks, William

In Energy efficiency and durability | Asked By Scott Nunnelly | Sep 21 13
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