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14 Answers

Best location for fresh air intake for ERV/HRV

I can't have the fresh air intake on the wall since it would be quite difficult to drill thru the walls of my ICF home. I do not like the idea of going thru the roof since I do not want risk drawing asphalt shingle gases into my home. One option I am closely looking at is having it on the external soffit pointing down but I see at least one ERV manufacturer advising against it (I wonder why). Does any one see a problem with this approach?


In GBA Pro help | Asked By Venkat Y | Sep 8 14
9 Answers

Our roof is 1/3 hipped slate, and 2/3 is flat-sloped with a conventional roofing material, coated white

Our roof is 1/3 hipped slate, and 2/3 is flat-sloped with a conventional roofing material, coated white.

The underside of the entire roof was coated with spray foam a few years ago. The house was built in 1930, and the attic joists have a layer of rock-wool in them.

We'd like to get additional R-value, but don't want to screw up the expensive foam coating. Thanks for your time & attention.

In General questions | Asked By Woody Stemms | Sep 11 14
7 Answers

Rigid foam to catch drips from metal roof without decking

I'm building a small, one-story house with a simple 4:12 gable roof in Climate Zone 2, semi-desert Southwest with maybe 2 inches of snow per year. I want to use exposed-fastener, white-painted steel roof panels on purlins 2' oc on trusses 2' oc without any OSB or plywood decking. The panels are approved for such use. The attic space will be unconditioned, with R-38 insulation and a moisture barrier in the ceiling.

In Green building techniques | Asked By Jeff Cooper | Sep 8 14
1 Answer

How much rock under foam/slab in below grade basement?

We're building a new home in Central Iowa. The basement is below grade with 9' foundation walls. The concrete slab will be approx 8' below grade. Under the slab in this order is poly sheeting vapor retarder, 2" Foamular 250, 1" crushed rock then soil. There is 4" drain tule spec'd for next to the footing on the interior below the slab. That tule will tie in to the tile on the outside and it will all drain to a sump pit. How much 1" rock do I need under the foam and also under / over the tile on the exterior of the foundation wall?

In Green building techniques | Asked By Silas Hoeppner | Sep 10 14
21 Answers

Roofing leak near eave

Could a roofer possibly give an explanation as to what is occurring near my eave adjacent to a side wall. I have included pics. This has been about 8- 10 years in the making. There is currently a small depression (pic 1875) which is from deteriorating decking, but for 8-10 years there was dripping from underneath the soffitt below where this depression is pic 1871. The water also runs down alongside the house - pic 1869. (This water is not coming from the eave trough.

In General questions | Asked By eric michael | Aug 30 14
11 Answers

SIP overhang/soffit - Waterproofing

OSB 8" thick Polyurethane roof SIP that overhangs the wall by 24" - I am using peel & stick Ice & Water membrane to waterproof the roof and this roof SIP.

The build-up: For the 24" overhang/soffit, I am looking to just continue with the peel & stick/Ice & Water membrane and wrap the overhang, fascia, and underside of the SIP soffit with the same peel & stick membrane. I will then use 26 gauge aluminum to cover the area to provide protection.

The soffit doesn't need to be vented of course because it is a SIP and the peel & stick membrane provides the waterproofing.

In General questions | Asked By Peter L | Sep 6 14
3 Answers

Wood furring attachment to CMU

We are renovating a building where we are adding 2" of rigid foam to the exterior of the concrete masonry unit walls. So the wall system will be as follows from the inside surface to out;

  • 8" CMU
  • 2" Polyiso
  • 1x Wood furring
  • Fiber cement siding
  • In Green building techniques | Asked By Joshua Lloyd | Sep 9 14
    4 Answers

    How to seal and insulate an enclosed rim joist in an older balloon frame house?


    I hope you don't mind my asking this question here. I've talked with a number of contractors and gotten different answers from each.

    I recently moved into a 1930s balloon framed home in Maryland. The ground floor is quite cold in the winter, and I'm getting ready for next season. The walls are insulated with fiberglass batts; the attic has blown fiberglass to R-40 (but I don't know the extent of the air sealing in the attic, though my suspicion is that it is not sealed).

    In General questions | Asked By Joe Emerson | Sep 8 14
    1 Answer

    What's best method of converting a "semi-vented" crawl space with a rat slab w/no vapor barrier into an unvented crawl space?

    Wondering how best to handle the crawl space of a tri-level in upstate NY (built in late 70's). The house is "semi-vented" (2 vents on the east wall half covered by mulch & soil on the exterior and 2 vents going into a garage on the south wall that have been blocked off with wood). Entrance to the crawl space is provided by 2 common doors from the lower level. The house is heated with hot water baseboard, and currently has fiberglass insulation between the joists... which plays out just like you'd think - the insulation is very wet throughout the crawl space.

    In Green building techniques | Asked By Stephen Mager | Sep 9 14
    1 Answer

    Insulating an unvented low-slope roof

    Been reading through many articles throughout the web discussing the varied approaches to insulalting different roof types in varied climates with various materials. that said I cant seem to find (or may have overlooked) approached to insulating my roof.

    I live in Washington DC and here's what I have:

    Flat roof comprising of (bottom to top):
    2 x 8's;
    Plywood strips;
    2 x materials ripped to provide slope, laid on top of the plywood strips and installed to create a valley in each corner of the roof;
    5/8" CDX;
    2" thick Isoboard;

    In Energy efficiency and durability | Asked By Alexander Brace | Sep 9 14
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