Healthy Indoors Magazine - USA Edition

HI August 2017

Healthy Indoors Magazine

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Page 20 of 49

Healthy Indoors 21 compounds containing nitrogen belong to a class of organic chemicals (chemicals that contain car- bon) that are related to ammonia and that are called amines. Many amines have a strong, am- monia-like or fish-like odor. The odor seems strongest when the insulation is heated – when the sun is shining on the walls or roof where the insulation is present. In a few hous- es I investigated, the dead-fish odor didn't dissipate over time to a level the homeowners could tolerate. One option would be to cover the insulation with foil and metal tape; this would prevent most off-gassing. Sometimes, though, owners decided to have the insulation completely removed. This can be an expensive process. In one home, the foam was sprayed into wall cavities that were then covered with thousands of dollars of custom trim work. In another home with tongue and groove cathedral ceilings, the contractor had to remove all the roof shingles and sheathing to avoid damaging or hav- ing to remove the ceilings. One newly constructed house that I investi- gated ended up being demolished, because in the end it was more cost effective to build a new house rather than demolish the finished walls to get rid of the insulation. being "pressurized" by the mechanical system, so air was flowing out of the room into the adjacent work space where the air pressure was lower. That air flow was carrying the odors of the bathroom use and the sprays. The simple fix was to lower the supply-air flow in that bathroom by slightly closing down the supply louvers. Construction materials One couple with an "empty nest" built their dream house in which they intended to enjoy their impend- ing retirement. Shortly after they moved in, howev- er, the wife experienced headaches and found it difficult to sleep at night. Whenever she spent time away from home, she felt better (a strong sign that the house was a problem for her). In desperation, she finally moved into a furnished apartment, while her husband stayed behind in the house. The house was large and open, with lots of light. The first floor had an omnipresent, mild chemical smell. I found that the odor was stron- gest at the corners of walls and at intervals of sixteen inches on vertical "strips" from floor to ceiling. These areas coincided with where joint compound was applied to drywall joints and fas- teners during the construction process. The drywall installers must have used joint compound to which fungicide had been added. The joint compound was off-gassing an odor that was causing the woman's headaches. The solution? Remove all the drywall, unfortunate- ly; or cover it with another layer of drywall with aluminum-foil backing (chemicals cannot off-gas through aluminum foil). I'm working with a number of clients who own houses with spray polyurethane foam (SPF) insu- lation. SPF is created by mixing two parts (A+B) in an application gun. If part A and part B are not mixed in a 1:1 ratio or are mixed at incorrect tem- peratures or pressures, or if the insulation is not installed during recommended temperature/hu- midity conditions, the foam can off-gas an odor. A catalyst is required to facilitate the chemical reactions that occur when the foam is produced. This catalyst must contain nitrogen. Many organic SPF foam installed in an attic and covered with foil May Indoor Air Investigations LLC I'm an indoor air quality consultant, but I was educated as a chemist, so bear with me while I go into a little science here.

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