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9 Answers

Water and Wood at Micro and Nano Scale

here is a micrograph of white oak

I am trying to verify the scale
Are the units in Microns?
does the visual scale in the lower left corner indicate 100 microns?
Or in other words 100,000 Nanometers?

In General questions | Asked By John Brooks | Sep 26 10
1 Answer

Double-stud walls and air barriers

I am working on the design of a double-stud wall residence (approx. 12" thick) in climate zone 6b and am currently detailing the air barrier & estimating costs on a variety of different products/approaches.

The insulation will consist of dense pack cellulose and the exterior cladding will be lap siding on a ventilated rainscreen in some areas and vertical board & batt (basically a ventilated rainscreen on its own) in other locations.


In Green building techniques | Asked By James Kennedy | Feb 8 13
9 Answers

Warming passive make-up air for exhaust only ventilation

I need advice on where to locate and how to condition (or at least protect occupants from the cold flow) incoming make up air. I need to bring the rigid vent pipe on the exterior (unconditioned crawl space) under the floor and enter through my 12” insulated floor baysup. There is no suitable wall or soffit entry point for the intake. I can install more than one intake if necessary.

I have 3 draws: (1) an electric clothes dryer, (2) a single 80 -120 CFM bathroom exhaust fan and (3) a 120 CFM range hood; plus a small wood stove. The Prestige boiler is direct vented.

In General questions | Asked By Oak Orchard | Feb 7 13
2 Answers

I am working on a single family house in Climate Zone 5 in New York State.

The first floor is a suspended concrete slab with radiant heat over wood framing. The basement is totally buried with the exception of the top 6". It's covered in 2" of rigid insulation. It will be heated but to a lower temperature than the first floor.The only opening into the basement is a bilco door.

I had originally specified 1" white Dow to be used under the first floor joists but am wondering if I can specify instead one of the radiant barrier materials in the interests of economy. Thanks.

In Energy efficiency and durability | Asked By Linda Gatter | Feb 7 13
2 Answers

Vapor barriers inside AND outside of unvented crawl space?

I have been trying to figure something out for days. Maybe you can provide some clarity.

If I am building an unvented crawl space, and have an interior vapor barrier on the ground and sealed to the stem wall, with rigid insulation over it, do I need to have a vapor barrier on the EXTERIOR of the foundation wall, as well?

Do I even need to brush asphalt on the exterior CMU or do I want it to breathe?
Thanks so much!

In Energy efficiency and durability | Asked By Beyhan Trock | Feb 7 13
15 Answers

Would this building envelope work? Zone 4A in Japan

Thanks to GBA members' answers I received to an earlier question ( www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durab... ), I have decided to abandon local building practices. I am aiming to build a well-insulated & airtight 600 square foot house for my family.

In General questions | Asked By Eric Matsuzawa | Jan 26 13
2 Answers

How long should VOCs linger after removal of the source?

I purchased a home n Florida built in 2005 which I discovered had a VOC problem after closing. There is a aromatic sort of piney smell in the house that attaches to anything left in the house for more than a few hours. The house is empty of any furnishings, had engineered wood floors glued to the slab over 50% of the house with tile/carpeting in the rest. The kitchen and bath have cherry wood cabinetry and there are plastic blinds on the windows. I removed one cabinetry box from the home and didn't notice the odor. The odor doesn't extend into the attached garage.

In General questions | Asked By Mary Loughran | Feb 7 13
3 Answers

Can pressure-treated lumber be used inside of a dwelling as framing material?

...such as where basement partitions on bottom plates of a wall or where concrete meets lumber, and what type of barrier is required between lumber and concrete?

In Building Code Questions | Asked By John Poulette | Feb 7 13
15 Answers

Ineffectiveness of increasing R-value with more than 4 in. of closed-cell spray foam?

I have been told a number of times that using more than 4" of cc spray foam (in a wall or roof assembly) has little value at increasing r-value. In other words, does using more than 4" not have a linear increase in r-value? The reason I ask is b/c I need the recommended r-35 against the bottom of my roof sheathing (with blown-in cellulose in the remainder of my cathedral truss) to prevent the roof sheathing to dip below the dew point and create condensation. Any thoughts? Thanks.

In GBA Pro help | Asked By Matthew Michaud | Feb 2 13
4 Answers

Controllng infiltration through entry way doors

In my caulked-to-death cottage, there is annooying air infiltration around my front and back doors. The inflow increases when exhaust fans are turned on, the negative pressure results in the opening up/softening the connection and allowing air in.

I am surprised not to be able to find much info on how to seal entryway doors. I can't find any lock-sets or after-market door sealing solutions that convince me of their effectiveness.

In Energy efficiency and durability | Asked By Oak Orchard | Feb 5 13
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