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3 Answers

4" of 2 lb closed cell spray foam will go on underside of roof sheathing....so roof needs to dry to outside; hence why I am using #30 felt/tar paper instead of a non-permeable ice & water shield.

However, to get my Class A fire rated system, I need to use an ASTM D 3909 cap sheet over the tar paper. How well is this system going to be able to dry to the outside and will there be any issues with this system?

The roofing material is a synthetic shake; Bellaforte by DaVinci.

Thanks-Eric

In General questions | Asked By eric Mikkelsen | Aug 29 14
34 Answers

My house has high levels of CO2 / carbon dioxide, every room is between 1100 ppm to 1200 ppm according to an air quality test I had. There are only 2 grown occupants and it's a 1000 sq. ft. brick house. No pets or plants, gas stove / furnace / water heater.

The basement was the only area that had between 900-1,000 ppm of CO2. I've read ASHRAE likes to see under 1000 ppm of CO2. We do have headaches & drowsiness but aren't sure if it's strictly from CO2. For reference, our CO (carbon monoxide) numbers were all under 2 ppm.

In General questions | Asked By Jeff Watson | Mar 9 14
2 Answers

Hello,
I have a 1 1/2 story cabin that I am insulating. The second story was constructed using engineered attic trusses. The top chords are 2 x 6 and the knee walls are 2 x 4. Metal roof with soffit vents and ridge vents. My plan is to fur the sloped top chord with a 2 x 4 on edge. This would provide me with 9" of space. I will put allow 2" of ventilation space and install 1.5 " XPS rigid foam board as my baffles, followed by 5.5" of roxul comfort batts, 6 mil poly vapour barrier and drywall. The 2 x 4 kneewall I will build out also with 2 x 4, giving me 7 inches of space to fill.

In General questions | Asked By Dawn Roberts | Aug 30 14
9 Answers

My designer and I are designing a house as close to passivhaus standards as we can get. We have agreed to design it with SIPs but he thinks a truss roof with spray insulation would work just as well. I'm thinking a SIP roof eliminates potential for thermal bridging and is less costly to install versus the truss roof.

In Green building techniques | Asked By scott schroeder | Aug 29 14
4 Answers

I am replacing my existing siding and I am doing the following -stud - 5/8" plywood - 1-1/2" of Polyisol, 3/8" rain screen, WRB, fiber cement siding. The house is in the San Francisco bay area on a hill with a stepped foundation.

In Energy efficiency and durability | Asked By Randy Mason | Aug 30 14
3 Answers

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
1 Answer

I live in the San Francisco bay area and am going to use 1-1/2" rigid foam board and a rain screen on the exterior of my house. I have read numerous articles in regards to using insect screen at the tops and bottoms of the rainscreen wall, however no specific details about the type of insect screen is ever mentioned.

There are numerous types of insect screens (Aluminum, Fiberglass Bronze, galvanized, etc.) available.

In Energy efficiency and durability | Asked By Randy Mason | Aug 30 14
6 Answers

My 1927 house has balloon framing, real plaster walls on rock lath, and no vapor barrier. It has cedar shingles over tar paper.

If I blow insulation into the walls, will I create a problem with vapor from the house condensing inside the walls? Even without insulation (current condition), can I close the top of the walls in the attic or will that also allow water vapor to condense in the walls?

In General questions | Asked By RUTH HENDRICKSON | Aug 29 14
5 Answers

I am in zone 5A and I have a problem of excess humidity in my ICF home with no abnormal sources of moisture (5 occupants of a 2150 sft home with a full basement). This results in condensation on the wall of windows facing a pond on the north.

Since a dehumidifier will also dump heat into the home helping my all-electric furnace heat the home, I am wondering if it would cheaper to run the dehumidifier than to use an ERV to lessen the humidity in the home. I realize in the latter case, there's some loss of sensible heat that the electric furnace would then have to compensate for.

TIA.

In Energy efficiency and durability | Asked By Venkat Y | Aug 29 14
1 Answer

So based on everything thing I am reading should we be using R3 R4 or R5 for each inch of Polyiso since it decreases in performance as it gets colder. I seem to be seeing some variation in Answers. I am in zone 5 and was planning on putting 5 inches of Polyiso.(thinking that was R 30 Roughly but if is is only R 15 when coldest that is a problem) Now it seems like I would be better served with three inches of polyiso with EPS on top. I have access to 1.5 or 2.75 inch EPS. Would I still be OK with 3 inches of polyiso and 2.75 inch of EPS on top?

In Energy efficiency and durability | Asked By terry grube | Aug 29 14
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