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9 Answers

Whole House Dehumidifier - Is it worth while?

I'm building a new home in Climate zone 6 (central PA). It will be well insulated and air sealed. While I'm still wrestling with the ERV vs dedicated bath exhaust fan decision, my HVAC contractor has just further muddied the water. We are going with a closed loop geothermal heat pump. He has recommended we install a whole house dehumidification system (with outside air capability). Specifically he recommends installing a Honeywell DR90. In theory this makes sense for those days that are not hot, but still humid. Any thoughts or opinions? Is it worth the net installed cost, $1400 net.

In Energy efficiency and durability | Asked By Jim Orasky | Mar 16 12
10 Answers

What can I cover my exterior foundation insulation with?

I have 2 layers of 1.5" XPS with staggered seams glued to a damp-proof block wall. The exposed wall ranges from 6" to 2' above grade. I saw the article with some suggestions for protection like SBC and protecto wrap, but wondered if I could use vertical vinyl siding. I will use a termite shield and drip edge over the foundation covering, and I have the foam covered with roll roofing down to the footer (30" below grade). I was also considering stone veneer but was worried about how to attach it.

In General questions | Asked By Matt Black | Mar 19 12
4 Answers

Is duct sealing considered part of infiltration measures in older homes?

The basic scenario is in a older home when you seal the ducts it causes infiltration numbers of the blower to drop significantly. By code would you count that to the infiltration measures or keep it separate. And if you keep it separate what would be the right way of running the test and completing the work.
Thank you very much

In Building Code Questions | Asked By Adrian Loza | Mar 19 12
18 Answers

Under-slab foam: How thick? Spreadsheet for review

I just built a spreadsheet to look at the savings and cost of various thicknesses of foam under a slab. In another thread, I had questioned the PassivHaus use of 14” as being excessive, so I thought I’d take a simplified look for myself, ignoring inflation, etc. This is for zone 8, 14,000 HDD, and $60 for a 4’x8’x4” sheet of 15 psi EPS.

In Plans Review | Asked By John Klingel | Feb 20 11
3 Answers

Attic Ventilation

I'm planing the ventilation for my attic. I'm going to have loose fill cellulose to an R-60 and a friend of mine was mentioning that I don't need to vent the soffits if I have gable vents and ridge vent because the house will be air tight. He was also mentioning over ventilating and possibly doing something with the pressure of the house. Anyway I had planed on using soffit vents as it seemed to be the fail safe way for venting. The house will have an HRV system also.

In Green building techniques | Asked By Mark Hinkley | Mar 17 12
19 Answers

"Study group" - resilient design.

I have been thinking about the "pretty good house" (PGH) concept lately and also about "resilient design".

I find it helpful to think of resilient design in terms of "risk management".
From a risk management perspective, much of what is already considered in the design process can be called "resilient design"...
For example, bulk water intrusion into an assembly represents an identified risk that many designers mitigate by specifying appropriate flashing details.

From a risk management perspective then, "resilient design" isn't something new that needs to be considered...

In Energy efficiency and durability | Asked By Lucas Durand - 7A | Mar 16 12
7 Answers

Follow-up to Spencer Burnfield's question of 13 March: Closed vs. Vented Crawls in the Pacific Northwest.

I'm still conflicted about closed crawls in the Zone 4 Marine climate of the PNW. Studies done by Washington State U. have shown that vented crawls "work" in this climate: i.e., they don't cause the problems they cause elsewhere. Also, closed crawls allegedly exact a small energy penalty. Several local building experts have thumbed their noses at the East Coast "fad" for closed crawls. "The more vents the better," one says.

To me, though, something doesn't "work" just because it isn't quite as bad as it is in other climates. I still don't see the point of open crawlspaces.

In Green building techniques | Asked By Gordon Taylor | Mar 18 12
3 Answers

Does additional air sealing improve performance linearly or exponentially?

I just had two energy audits done on my 1959 walk out ranch: one throgh the utility company's program for $50 and one through an independent company for free. I wanted to see how the two compared so I could better advise my clients. The independant company was more enthusiastic about air sealing, but of course this also makes for a better sales pitch.

In Energy efficiency and durability | Asked By Hallie Bowie | Mar 19 12
10 Answers

Moisture problems with Vapor Barrier - Part 2 - Another question

A follow-up question:
Is there a problem having paper backed insulation and a plastic vapor barrier on walls and ceiling? When I observed moisture problems it was not condensed on the paper or plastic, but on the coldest surface i.e. the roof sheathing and Styrofoam air ducts. Some have said the plastic is the problem and the walls/ceiling need to breathe while my architect says install the plastic for air seal and thermal efficiency. Confused! What's correct?

In GBA Pro help | Asked By Tony Moore | Mar 18 12
7 Answers

Where to place the vapor barrier in a concrete slab on grade with radiant floor and integral colored concrete?

We are building a 2,200-sq.- ft. single-story concrete slab-on-grade home with hydronic floors throughout and will be integrally coloring the concrete. Stem walls will be poured and then interior slab will be poured. We are installing hydronic PEX directly to the XPS foam, which will be taped, and then placing rebar on chairs above the PEX. The slab will be 5 inches thick with fibermesh such as Stealth 150.

In GBA Pro help | Asked By A Lalande | Mar 18 12
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