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4 Answers

Insulation dew points and archaic insulation

I have a couple of questions, both somewhat academic since there may be little to do about them.

I live in a 1938 1.5 story (Cape-style) house in St. Paul, zone 6. About 3 years ago the shoddily-added back porch was falling apart and the roof shingles were shot , so I tackled both in one, replacing the back of the house with a new addition, and re-roofing the entire house using this "cold roof" article in JLC as a model (in short, adds 3" XPS foam plus 1-1/2" air gap above the original roof): http://www.jlconline.com/rooftop-accessories/retrofitting-an-insulated-c...

In GBA Pro help | Asked By Graham Allan | Oct 20 14
9 Answers

“Air-sealed” can light retrofit vs. Tenmat cover in attic?

I’m planning some air sealing work in my attic. I’ve got a bunch of recessed can lights to deal with, and I had been planning to use Tenmat rock wool light covers on the attic side. This would involve caulking (say, Tremco acoustical sealant) or foaming to seal the Tenmat cover, plus taping up any cuts to allow for electrical wires, etc. After first going into attic, pulling back existing insulation, sweeping the area clean, etc.

In Energy efficiency and durability | Asked By andrew c | Jun 22 14
2 Answers

Mold in crawlspace

I live in Gadsden Al,and we purchased a home and for a couple years its been smelling old,i went under the house and found the mold on the west wall where the flower planter is outside the house and by the pipes coming from the bathroom. I fogged the crawlspace very well with corcodium and I no I have to clean the walls too. But I need to bring the height of my front yard up 1 ft and at a slant to stop the water from ever going back under the house.the flower planter is 11/2 ft high and 12ft long 11/2 ft wide. and has brick on the outside.

In GBA Pro help | Asked By weldon jones | Oct 21 14
1 Answer

Interior insulated cornice for use under low-heel roof trusses?

Has anyone found, used, or developed an interior insulated air-seal cornice for the wall to ceiling connection below a "low heel" truss eave condition that does not accommodate full attic insulation thickness?

In Energy efficiency and durability | Asked By Albert Russell | Oct 21 14
19 Answers

Rising power plant energy cost

See attached....SDG$E(San Diego, CA) raised the minimum tier from 12 cents to 15. We don't buy in and didn't run the AC much this year in baking heat, probably what most are doing, that and getting off the grid. This is sign of those still on the grid having to pay for the ones that are off. In KS, cost went down from 10 cents last year, to 9 probably in fear of going bankrupt like Cali. Lets see what they do with gas.

How about where you live, going up or down?

In Energy efficiency and durability | Asked By Terry Lee | Oct 15 14
19 Answers

Enclosed room on slab

In the midst of an enclosed porch over slab job. Plans initially included flash on un-vented roof, rigid foam on exterior, house wrap and fiberglass in walls.

In Energy efficiency and durability | Asked By Jason Schatz | Oct 16 14
1 Answer

What is the best ventilation system for a passive design cafe/restaurant?

We are trying to design a passive cafe/restaurant building and i want to know the best ventilation system to use for the building please.

In PassivHaus | Asked By monita taghva | Oct 20 14
6 Answers

Reasonable retrofit efficiency goals

As I battle with an hvac solution for our home, we are leaning more and more towards trying to reduce the load further. I'll mention some details of my own house a bit below but I'm actually asking in hopes of a more generalized discussion of what a reasonable retrofit btu and ACH50 goal is.

I did some reading tonight in the hopes of answering this question but didn't find any useful rules of thumb. I know, the old HVAC rules of thumb have caused a lot of grief. I'm not asking for a rule of thumb about BTUs/sf for heat but rather what is rationally achievable in a retrofit scenario.

In Energy efficiency and durability | Asked By Keith H | Oct 19 14
5 Answers

Insulation design

Climate zone 2a.....south east Georgia coastal island. Bought a 1962 block one story house, The interior walls are painted block....we like the beach look associated with this concept. So, all insulation must be on the exterior of the house....which now us striped to bare block. Interested in the correct approach for water management and insulation. Exterior will eventually be cedar shingles.. Sort of thinking....spray closed cell between furring strips with ridged foam sheeting over the spray foam and strips. Then plywood covered with rain drainage screen topped with shingles.

In GBA Pro help | Asked By Robert Brown | Oct 17 14
5 Answers

IRC 316.4 - Code interpretation on the use of rigid foam as air barrier on backside of attic knee wall

My insulation plans for my attic kneewalls were to install two layers of 2" eps with staggered and taped seams, then install damp sprayed cellulose in the 2x4 stud cavity, followed by 1/2" drywall. I believe that a thermal barrier is required since I have usable attic space, but I am unclear whether this thermal barrier must be installed on both sides of the stud wall, or only the portion of the stud wall that faces the interior of the attic room. The gray area is whether or not the areas behind the stud wall are considered the "interior of the building".

In Building Code Questions | Asked By Rick Van Handel | Oct 17 14
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