Building Science

Tear at the fastener

Beyond Water Resistance

Posted on April 23, 2009 by Peter Yost

Housewraps and Building PaperTypically referring to Grade D building paper, this product is an asphalt-impregnated kraft paper that looks a lot like a lightweight asphalt felt. The Grade D designation has come to mean that the building paper passes ASTM D779 (minimum 10-minute rating with the “boat test”) and different products are called out as “30-minute” or even “60-minute” based on D779 results. At times confused with roofing felt, roofing felts and building paper differ in two ways: felts are made of recycled-content paper, building papers of virgin paper; felts are made of a heavier stock paper; building papers a lighter stock. See also roofing felt.: Beyond Water Resistance

Tensile strength, vapor permeability, and pliability are important, too.

In a recent blog post, I covered water-resistive barrierSometimes also called the weather-resistive barrier, this layer of any wall assembly is the material interior to the wall cladding that forms a secondary drainage plane for liquid water that makes it past the cladding. This layer can be building paper, housewrap, or even a fluid-applied material. (WRB) tests to separate the wheat from the chaff in terms of water resistance. But a good WRB has other properties as well.

Rotten sill

Don’t Let This Happen to You

Posted on April 12, 2009 by Michael Maines

Door design details
The photo at right is from an entry that's just 15 years old. Fortunately, it was able to be repaired. I haven’t always been so lucky. Let’s just say that replacing subfloor and framing is no fun. A safe assumption is that, for one reason or another, doors always leak. They shouldn’t, but they do. Seals wear out. Wind blows. Jambs rot. Sills crack. Weepholes clog. Following are some ways to mitigate the chance of damage.

    Modified boat test

    Simple DIY Tests for Housewraps

    Posted on April 10, 2009 by Peter Yost

    How do you know if your housewrap really works?

    In the good old days, we weatherlapped 3-ft. courses of building paperTypically referring to Grade D building paper, this product is an asphalt-impregnated kraft paper that looks a lot like a lightweight asphalt felt. The Grade D designation has come to mean that the building paper passes ASTM D779 (minimum 10-minute rating with the “boat test”) and different products are called out as “30-minute” or even “60-minute” based on D779 results. At times confused with roofing felt, roofing felts and building paper differ in two ways: felts are made of recycled-content paper, building papers of virgin paper; felts are made of a heavier stock paper; building papers a lighter stock. See also roofing felt. underneath our wall claddings, and that seemed to work just fine. But then along came all sorts of snazzy “gift wrappings” (a.k.a. housewraps) in handy, 9-ft. rolls. Some claimed to be both air barriers as well as water-resistive barriers; others claimed to be vapor permeable. Along the way, it got pretty confusing about just exactly what the housewrap’s job is in our walls. (For a practical and detailed perspective on housewraps, see “Making Sense of Housewrap”.)

    Climate Smart

    Reducing Our Carbon Footprint — Part Two

    Posted on April 6, 2009 by Annette Stelmack

    Boulder County’s Climate Smart loan program

    Part Two: A deeper level of action
    The first major step toward reducing your carbon footprintAmount of carbon dioxide and other greenhouse gases that a person, community, industry, or other entity contributes to the atmosphere through energy use, transportation, and other means. is understanding how much energy you use. Energy efficiency is often more cost effective than renewable-energy alternatives. The target is to use less energy for the same amount of heating, cooling, lighting, and of course, powering appliances, the stereo, televisions, and iPods. Fortunately, a big benefit of most energy-efficiency measures is creating greater comfort in the home over the long term.

    HVAC

    Can’t We All Just Get Along?

    Posted on April 3, 2009 by Rob Moody

    I’ve been absent from the blog for about a week. My apologies. I was traveling and studying for the LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. AP exam, which I took on Monday this week and passed. I have since been recovering. I’m glad it’s over, and I am looking forward to enrolling in the LEED AP+ program when it comes out later this year. The test was pretty much what I had expected, and I’m definitely glad that I studied.

    Mold in a vented attic

    Don't Try This At Home: Armchair Building Science

    Posted on April 2, 2009 by Peter Yost

    The homeowners called me after a certified home inspector stated that the attic was underventilated and moisture was building up as a result. The roof assembly had soffit vents at the eaves and two gable-end vents. These vents would not be as effective as ridge-to-soffit ventilation, but were probably close to building code requirements (see Green Basics – Attics).

    Climate Smart

    Reducing Our Carbon Footprint — Part One

    Posted on March 31, 2009 by Annette Stelmack

    How many of you have searched the Web to calculate your carbon footprint? I have, and it is exciting, intimidating, and perhaps an all-consuming process. More than 10 years ago my husband and I signed on with Xcel Energy support wind power. We installed a programmable thermostat and set the temperature higher in the summer and lower in the winter.

    USGBC Education Provider Program

    LEED Can Change, Part Three: The Education Program

    Posted on March 24, 2009 by Rob Moody

    Here’s where I start to get a bit giddy (I know that’s geeky). When I was teaching high school environmental science, I had my students create and carry out green building projects. Partially due to my excitement about the topic, I had some of the best results in that class of any unit that I taught. The basic model that I utilized for most of my major lessons was the same: I would verbally present the content, followed by a demonstration of the topic, and conclude with a lab or project so that the kids could experience the concept first-hand.

    hygrometer

    Moisture Sources, Relative Humidity, and Mold

    Posted on March 24, 2009 by Peter Yost

    A little water goes a long way

    We hear a lot about how moisture can be an indoor pollutant in tight houses. But just how much moisture can be a problem; how does boiling a pot of water compare to a 15-minute shower? This keeps some of us mold worrywarts up at night, so I thought it would be a good idea to run some numbers.

    thermal bridge - steel

    Thermal Bridging

    Posted on March 19, 2009 by Peter Yost

    Everything is relative — especially when it comes to thermal bridgingHeat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel. . Thermal bridging occurs wherever assembly components with low R-values relative to surrounding materials span from the inside to the outside of a building assembly. Thermal bridging takes place in wood-framed assemblies because, although wood is a pretty good insulator at about R-1 per inch, it is at least three times more thermally conductive than any cavity insulation, which start at about R-3.5 per inch.

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