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A Forum of Green Home Building Experts and Members

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Much of the value of this site is the pooled experience of members and their willingness to share it. One way is by using the comment boxes that follow every post. This page offers a Community area formatted for Questions & Answers. Please notice on the right that we've divided the Q&A forum into topics to make it easier to find your area of interest.

Anyone may ask a question--about anything within the realm of residential green building--and anyone may answer. Sometimes one of our 15 Advisors may chime in; in other cases, you'll get the wisdom of some of our members who have experience with the detail, material, code, etc. that prompted the question. We encourage everyone to give us the benefit of both their questions and answers. The usual rules of courtesy apply.

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3 Answers
What's the range of window air leakage values for good-quality US windows vs. garden-variety vs. Passive House-quality?

It's very hard to find published window air leakage rates (in cfm/ft2), harder still to get independent test reports with this information. So far I've found the following data points:
* a maximum of 0.3 for all of one US mfr's product line (in an internal manual);
* .02 for a tilt-turn unit by same mfr (from independent test report);
* .003 for a Canadian mfr's tilt-turn unit (from website literature).

I've also been told that the test apparatus doesn't yield a result smaller than .01.

In Green products and materials | Asked By Ann Edminster | Sep 19 09
34 Answers
Hybrid Insulation Techniques

Many insulation companies in our area have begun to sell hybrid insulation systems. In a standard 2x6 wall, they will spray 1" of closed foam inside the wall cavity and then fill the rest with cellulose. The idea is to get all the benefit of the air sealing, but then to get the rest of the R-value from the much less expensive cellulose. I can foresee many potential building science issues with this, but it's hard to compare to anything out there.

Does anyone have experience with these systems? How do they perform? How is their durability?

Thanks.

In Energy efficiency and durability | Asked By Adam Stenftenagel | Mar 2 09
2 Answers
Is Tripolymer spray foam insulation a 'healthy' choice in insulating an older home?

We are looking at insulating an older home that has poor insulation (original part of the house 1850, additions in 1970) and are tempted by this Tripolymer product. The owner of the company claims that it is a 'green' product with no health risks. I can't find any information to the contrary as all the sites I'm coming up with are sponsored by foam companies. Do you have any information on the potential downside of this foam insulation? (PS: CL&P, our electric supplier is offering a $1 per foot cash back for insulating older homes, so there is a significant savings to us if we do it).

In Green products and materials | Asked By Amanda Cordano | Mar 13 10
6 Answers
Can I build an old-fashioned vented crawl space with modern Lstiburek reccomendations?

Joe Lstiburek, the respected building scientist with Building Science Corporation, provides an approach to building vented crawlspaces in energy efficient houses. http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-c...

In GBA Pro help | Asked By Michael Chelnov | Mar 12 10
1 Answer
Will a wall funace meet the energy code if heating many rooms

A mechanical contractor suggests heating a1000 s/f 3 bedroom condo with a wall furnace installed in the main room. The heat will be transfered to other rooms by the installation of through the wall fans. There will be one thermostat on the furnace. Will this meet any kind of energy code. This is in massachusetts

In Energy efficiency and durability | Asked By joe | Mar 13 10
7 Answers
Using aluminum flashing as radiant barrier

As part of a bathroom remodel I asked the contractor to install a radiant barrier inside the wall behind a radiator. I had envisioned the use of the foil type material, but instead he used a sheet of aluminum flashing. I haven't yet determined whether he left an air gap behind the flashing, but if he did, will the flashing be at all effective? I assume that without the air gap it would be ineffective.

In Energy efficiency and durability | Asked By John Sullivan | Mar 12 10
16 Answers
Sub pump with 2" discharge pipe clogging up from silt clay in the water.

I have a 10'deep x 5' diameter pre-cast concrete man hole with two pumps alternating for my 6" footing drains located outside of the house. This is a new construction house. I put down 12" inches of trap rock in the basement floor with 4" perforated pipe and grid pattern tied into my six-inch footing drains. I also put down filter fabric before the trap rock went down and over the 6"perforated pipe. What is happening is a orange colored clay is sticking on the inside wall of the 2" pipe closing it down to 1"on the inside walls. Seems like every six months this occurs.

In GBA Pro help | Asked By Peter Fusaro | Mar 12 10
3 Answers
Anyone have any experience using tankless gas water heater w/ radiant floor? in a conditioned crawlspace?

Doing major remodel and plann to add to kitchen/new bath w/ tile floors over crawlspace. Crawlspace to be conditioned space - sealed and insulated at perimeter ala BSC specs. Was planning to do radiant floor heating because done't want/ don't like forced air over tile floors. Has anyone used gas tankless water heater as radiant floor heat and domestic hot water source (combo)?

In GBA Pro help | Asked By mike | Mar 12 10
5 Answers
Is this a good plan for wood exterior siding?

I am residing my house located in Minneapolis, MN built in 1907. The wall assembly is -- plaster/lathe, wood framing, building paper, wood board siding, and the old wood lap siding (which will be removed except for the soffit/crown trim at the eaves.) Before residing I will be blowing dense pac cellulose into the stud cavities. My house is a 1 ¾ story gabled configuration with ~10” overhangs. The exterior wall are highly exposed to the sun and weather.

From what I have gleaned from this site a drainscreen installation will maximize the longevity of the wood lap siding and paint.

In Green building techniques | Asked By j chesnut | Mar 12 10
13 Answers
Tight Homes/Good Ventilation

I am huge advocate of building tight homes. Air leaks, to me, represent poor workmanship that wastes a huge amount of energy. But, just for a minute, I want to be the devil's advocate, primarily because I hear this argument all the time. Tight homes need good, dependable ventilation systems or the occupants will suffer and the durability of the building will suffer......whole house ventilation systems, exhaust fans in bathrooms, hoods, sealed combustion gas appliances, etc.

In Energy efficiency and durability | Asked By Ed Welch | Mar 9 10

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