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4 Answers

Not enough XPS over roof - should I vent?

I am in the Washington DC area - Zone 4. I just had a 1.5/12 single slope roof framed with 2x8's for a 14x20 new block wall garage. On top of the rafters there is a layer of plywood followed by 2" XPS rigid foam followed by another layer of plywood and then an ice and water shield across the entire roof. This week there will be a standing seam metal roof installed on top.

In Green building techniques | Asked By Calvin Bouchard | Feb 12 17
1 Answer

I have two specific questions regarding efficient home-run plumbing design

My wife and I are currently working with a local design/builder on a set of plans for a small home in Silver City, NM (4B). The main bathroom, mechanical room and kitchen are all grouped together on the 850 square ft main floor. A second bathroom, located directly above the main bathroom, is planned for the 550 square ft loft. The wall assembly will be 2*6, dense pack cellulose, 1 inch of EPS exterior the sheathing, and fiber-cement siding.

In Mechanicals | Asked By Aaron Beckworth | Feb 17 17
33 Answers


While I was on the subject originally regarding adding central air to my gas furnace, someone was talking about humidity levels in the winter and how dry you feel at home.
I just realized and was told that whole house humidifiers only work/operate anyway, when the furnace is actually running. Makes sense.
in my opinion, and having a hydrometer to prove it, whole house humidifiers are a waste of money, period.

In General questions | Asked By Dave Mac | Feb 15 17
2 Answers

What do you do when you can't find duct leakage issue?

Conducted an audit today on a manufactured home with a rectangular duct board system in the belly. Duct leakage testing resulted in NO reading at 25 pascals. We crawled under the entire home following the trunk lines and found no visible signs of broken or disconnected ducts that could explain such high leakage. Has anyone out there ever ran into a situation like this? If so what did you do?

In Energy efficiency and durability | Asked By Benjamin Barker | Feb 16 17
14 Answers

Kingspan Kooltherm - R-8/in?

Recently got sent a sample and some information on a new 'premium' rigid foam Kingspan is trying to market in the US after making it in Europe for quite a while. A little googling and this appears to be some sort of phenolic foam, maybe. Some of the claims in the literature have me scratching my head:

-R-8/inch. Seems awfully high for rigid foam. They claim this is from an ASTM C 518 test but the rep wouldn't send me the actual report.

In Green products and materials | Asked By Chris B | Feb 16 17
8 Answers

Mini-Split & Generator vs Wood Stove


I'm about to build a house about 8 miles outside of Brockport, NY (near Rochester). The lot has electricity but no gas. I would like to heat my house off mini-splits, and I'm currently having a Manual J done to determine feasibility. The footprint of the house almost guarantees that I will need more than one small mini-split rather than one central unit. I plan on having a backup generator.

Here's the question: Should I put in a wood stove for backup heat, or simply put a small minisplit on the generator?

In Mechanicals | Asked By John Ranson | Feb 17 17
13 Answers

How to fix my unvented cathedral ceiling roof assembly?

We tried to build a house with a fairly tight envelope based on reading I could find. Well, apparently I messed up, so really want some advise before I mess things up more.
House is in central Missouri( zone 4, but real close to 5). Small, 750 sf but with an open loft making it about 940sf. Sealed Concrete slab as the finished floor, and new construction ( under roof in may but moved in The next January). Red metal roof and one side of that faces north..
Walls are 2x4 and we used open cell foam with 1/4" foam inside the studs as an air ( not vapor) barrier.

In General questions | Asked By Brenda K | Feb 16 17
2 Answers

Rainscreen with gapped panels

Hello Again GBA'ers

We have a design for a ventilated rain screen ventilated with mixed cladding materials. This will be exterior to 6" of foam board insulation. One of the materials is Equitone, and the manufacturer recommendation calls for 3/8" gap between panels, they supply a butyl tape to face the furring strips, both to provide a dark color on the reveal and to provide a moisture barrier on the face of the wood furring strip. The panels are very long, and there will be long horizontal gaps.

Two questions:

In Green building techniques | Asked By Gerald Pehl | Feb 16 17
14 Answers

Noise from PEX/PVC drain pipes

We are at the stage of starting the framing for the new construction home in Pittsburgh. It is also a Passive House duplex. Our architect specified cast iron for domestic water drainage pipes (from shower and toilet, etc.), mostly on the account that these result in most quiet interior. For delivery of the water within the house, PEX is planned. Then we heard that iron pipes are more susceptible to clogging. Is some compromise, where pipes close to dining/living room are cast iron, and PEX elsewhere an OK option?

In General questions | Asked By Lucyna de Barbaro | Dec 6 14
5 Answers

I have a slab-on-grade floor (pre-1900) that sweats enough to where it can get slippery in summer

What can I do to prevent this?

The building is a raised "shotgun" in New Orleans. The lower area (about 7.5 ft. tall ) has been converted to an apartment. This is quite common here. Originally, these areas were used for storage only due to the possibility of flooding.

It is basically an unconditioned space, the hvac provided by window units.
The walls are insulated with Rolux batts, no ceiling insulation, and the old single pane double hung windows are fairly tight.
Is there an elastomeric, or epoxy type product that I can use to mitigate some of this problem?

In General questions | Asked By Roger Steinbrink | Feb 16 17
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