This post originally appeared on the Green Building Advisor website. www.greenbuildingadvisor.com
Pyrolysis [pahy-rol-uh-sis] noun
The chemical decomposition of wood by the application of heat alone in the absence of oxygen.
I used to perform risk assessment inspections for a couple small, local mutual insurance companies. These companies would insure properties that were considered “high risk”, most were rural, some were accessible only by boat, ATV or snowmobile and they were often a long way from the nearest fire department. Many had solid fuel burning appliances, usually a woodstove or fireplace. Part of my job was to make sure that the woodstove or fireplace had the proper clearances to combustibles, proper floor protection, and that the stovepipe and chimney systems met the requirements of the manufacturer and/or code. Most installations were safe, but every once in a while, I would find a home in danger of burning down. Continue reading “Building Science-Pyrolysis”
This year seems to be a good (or bad depending on how you look at it) year for ice dam problems in my area, the intensity of ice dams seems to change year to year. I was recently on an ice dam diagnostic with an insulating contractor and a general contractor, the home was built in the early 1990’s and there is evidence there have been issues from the beginning. We spent a couple hours testing this home, I’ll get into what we found in a bit.
Continue reading “Building Science-Ice Dams”
This three-part series first appeared on the Green Building Advisor website and has been condensed into one post.
An unconditioned and uninsulated crawlspace, an unsealed and uninsulated forced air heating system, and an uncovered dirt floor, which by the way has a sewage leak. If this were your home and you wanted to make improvements, where would you start? Continue reading “Building Science-Existing Construction Improvements”
As I write this post at the end of November, our outdoor temperature is 28°F with an outdoor humidity of 75%. Inside my home, the temperature is 70°F with a humidity level of 21%. Slightly uncomfortable humidity levels for my family. During last year’s polar vortex, when the temperatures reached nearly -40°F, my indoor humidity dropped to 9%, much too dry. Knowing what I know about building science, I will not operate a humidifier. This post will explain why. Continue reading “Building Science-Wintertime Interior Humidity”
I have talked many times about blower door testing, air sealing and air leaks in this blog, on the Green Building Advisor’s website, and more recently, in the pages of Fine Homebuilding Magazine. Most of what I’ve written deals with testing a home or techniques used in air sealing a home. This time I’m going to discuss the mechanisms that cause air to leak, there are only three of them, but first a little science. Continue reading “Building Science-Three Way Buildings Leak Air”
I’m a big fan of exterior insulation. It’s rarely used in my area, mostly because the State of Minnesota has eliminated that code requirement. It has to to with our wide use of polyethylene sheeting as a vapor retarder on the warm in winter side of a wall assembly and then adding a low permeance plastic insulation product as exterior insulation. These plastic foams would be the choice for most contractors, lower cost and easy to source. Very slow vapor movement in either direction when a wall assembly becomes wet. This posting isn’t going to get into the foam insulations, but more into what exterior insulation can do for a home. Continue reading “Building Science-A Benefit of Exterior Insulation”
I think most of us know of this man, one of the founders of The Energy Conservatory and designers of the Minneapolis Blower Door. I recently had the opportunity to chat with Gary. My intent with the interview is a little different from other interviews that have featured Mr. Nelson. I wanted to ask questions from a practitioner working in the field point of view. Continue reading “Building Science-An Interview with Gary Nelson”
If you’re a nerd like me, chances are you’ve heard of WUFI. WUFI is a German acronym that basically translates to heat and moisture movements through a building assembly. This is called hygrothermal analysis, it predicts wetting and drying of an assembly and lets us know if that assembly is risky. Continue reading “Building Science-WUFI”
Recently I was at a house conducting an energy audit when the homeowner indicated they were experiencing high humidity in the master bathroom. The windows were fogging up and they had some mold growing in one of the ceiling corners. They operate a bath fan regularly but it didn’t seem to remove any moisture. Continue reading “Building Science-How to Test a Bath Fan.”
I recently tested the Code Minimum House for air tightness at the rough framing stage. We ended up where I was hoping at this first test, .55 ACH50, 140 CFM. Given the volume of the home, the leakage area is equal to approximately 15 square inches. Continue reading “Building Science-A Visual for Blower Door Testing”