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13 Answers

Spray foam hybrid flash and batt help! wet wall cavity

We have new construction and have dry wall up and painted. Have spray foam 2" on exterior wall and flash and batt in wall cavity. Had a cold snap and with humidity in house the vapor went through wall on north and east side of house, hit the spray foam and condensed. We have heat on 62 and have 2 contractor size dehumidifiers running. The humidity level now is 50 , basement is 55. Has been a whole week. How long to dry. It is maine, and rainy out for next 3 days so feel that high humidity outside may help to drive vapor back inside.

In General questions | Asked By James Bernier | Jan 12 13
7 Answers


I am an energy consultant working with homeowners of existing homes. Could use a little input on a recent question. Customer has a second home, upstate NY, ZONE 5, and resides only weekends. Asks what should I set back my t-stadt to during the 5 days a week we are not here? 1998 home, oil boiler, 3 zones, indirect hot water heater. Typical conventional (ranch) construction. I have come to believe too much setback short-term can be both an energy and comfort penealty in an average to poor enclosure home.

In Energy efficiency and durability | Asked By mike Eastern NY | Jan 13 13
4 Answers

Double stud-wall construction: inner or outer load-bearing wall?

I have been investigating a lot of framing options to achieve a relatively inexpensive, high r-value wall and have decided on building a double stud-wall made of 2-2x4 walls with a 7.25" space in between (to achieve what I want for an r-value). I have come across differing methods of distributing the load from above; inner versus outer load bearing wall, or a combination of the two (inner for the second floor joists and outer for the roof trusses). And then there is Larsen Truss construction.

In Green building techniques | Asked By Matthew Michaud | Jan 14 13
0 Answers

Adam Cohen is teaching a course on starting a Design/Build business

In association with the Passive House Institute U.S., Adam Cohen will be teaching a course on the topic of "Designing and Building a Successful Design/Build Business."

The course will be taught in Philadelphia on February 18-19, 2013, and in Golden, Colorado on April 8-9, 2013. The cost is $375.

Adam will also present the course at Yestermorrow school in Vermont on July 20-21, 2013.

For more information, click here.

In General questions | Asked By Martin Holladay | Jan 15 13
7 Answers

Passive HRV - pressure balance ..a few questions

I would need help or pointers to understand a few things about air in a tight home
and HRV/exhausts/ pressure balancing.

Situation is the following :

Planned to run a DIY central AC at first using some GEO + AC pump..i scrapped that
and will be installing mini splits for AC next year .
Heating is all handled by electrical underfloor heating ...

Still have the 4" PVC ducts going through the house that will be used with 4" fans
in the machine room to "mix" and redistribute air at a moderate level

In Mechanicals | Asked By Jin Kazama | Jan 13 13
7 Answers

Passivehaus standard for commercial/industrial ??

I may have searched with the wrong words/terms,
but i haven't found anything that would be similar to the PassiveHaus standard
for commercial or industrial buildings ...

Does it exist ?
If not, could similar standards be applied to an industrial building design ?

Also, is there any software that we could use to design an industrial building as PHPP is used for houses ??

I will need to pin the following attributes :

- insulation quantity for walls, underslab and flatroof up to payback term of 10-15 years

In PassivHaus | Asked By Jin Kazama | Jan 13 13
8 Answers

Foil-faced polyiso for site-built baffles

First, thanks to everyone here for all of the advice and knowledge I've gleaned as a reader for the past year.

In GBA Pro help | Asked By David Baca | Dec 31 12
4 Answers

Rigid Foam Board in Crawl Space, Zone 3

I have a client in Zone 3 whose home is suffering from extensive air infiltration through the diagonally run dimensioned 1x subfloor that is covered with T&G hardwood flooring. The homeowner shows very little interest in encapsulating the vented crawl space and adding a dehu, and I cannot convince them to use SPF in their crawl space floor cavities either. They have read an article that suggests the installation of rigid foam board @ the bottoms of the floor joists.

In Energy efficiency and durability | Asked By Chris A | Jan 14 13
4 Answers

Attaching Insulweb to wall penetrations and preventing cellulose blow-out


(1) My ceiling: 24" o.c.12" deep rafters/cathedral; I have already installed 1/2" low-sag Sheetrock glued and screwed horizontally.

(2) My walls: 24" o.c. Larsen trusses.

(3) No top plates; Larsen truss wall bays pass directly up into the rafter bays. It's a cantilevered pole construction; building load hangs on 3/4" rod attached to poles (i.e. 6 X 6 square timbers)

(4) No basement: plumbing and heating PEX, wiring, etc. are in the walls; Stelrad radiators used for heating.

In General questions | Asked By Oak Orchard | Jan 10 13
3 Answers

Metal building and condensation

I got a call from a friend Friday. He was asking me about a metal commercial building that was having a problem with condensation on the underside of the roof. He had not been out to see it yet so he did not have all the details.

From what I gathered it didnt have insulation against the underside of the roof. There was an insulated flat ceiling with an air gap above. Supposedly not much room in between.

Does a metal roof require the insulation in contact with it to prevent the condensation. Or if the air barrier is improved will venting do the trick.

In General questions | Asked By Robert Hronek | Jan 14 13
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