Healthy Indoors Magazine
Issue link: https://hi.healthyindoors.com/i/1173074
Healthy Indoors | 31 Lint from dryer vented into crawl space and moldy insulation was present May Indoor Air Investigations LLC Beam decay due to moisture from dryer vented into crawl space. The top of the post was penetrating the bottom of the decayed beam. May Indoor Air Investigations LLC Central Vacuum Systems These are great to have, but they should vent to the exterior and not into the basement, garage, or crawl space; other- wise, if the canister is leaky, biodegradable dust can collect on surfaces and lead to mold growth. Devious Fragrances eled through an unheated attic. The warm, moist air from the dryer cooled as it traveled through the piping. Water condensed within the piping, leaked out the joints, dripped onto the garage ceiling, and created stains about every six feet where the sections of pipe connected. In another house, the dryer vented directly into a cold, attached garage. When I looked into the garage I faced a nightmare. Water was dripping from the walls and lint was stuck to surfaces. Moisture and biodegradable material mixed together equal? MOLD! Bathroom Exhausts In one house the bathroom exhaust vented into the soffit. Even with the fan off, there was significant passive air flow from the bathroom into the vent grille. I asked the home- owner to feed non-toxic smoke from my smoke pencil into the grille. I stood in the attic to watch the smoke-filled airflow as it flowed into the soffit. The smoke separated into two distinct flows. One narrow laminar band of smoke moved quickly along the sheathing, flowed up to the ridge vent, and then flowed back down the other side of the ridge pole. The second, slower-moving smoke cloud was turbulent and rose slowly until it encountered the ridge pole, at which point it sank to the floor of the attic. Why was this happening? The sun was shining on the sheathing so the sheathing was warm and created a narrow band of laminar air flow. That air rose up to the ridge and its momentum carried it over the ridge pole; the opening at the ridge vent was inadequate and there was no flow into it. The roiling, turbulent cloud that followed behind was almost the depth of the rafter bay and when it struck the ridge pole, it just sank to the floor. Crawl spaces When a crawl space is vented to the exterior, outside air can flow into the space. If the crawl space is connected to the basement, air can flow from the crawl space into the basement, because the air pressure in the crawl space can be greater than the air pressure in the basement. The vast majority of crawl spaces I've inspected contained mold growth because the relative humidity was not being ade- quately controlled. Crawl spaces open to the exterior can even contain pest infestations if there is exposed fiberglass insulation present (mice love to nest in the stuff). Then mold spores as well as mouse odors can flow into the basement and from there, up into the house. More than once, I've inspected a crawl space into which a dryer was vented. You can just imagine the moisture and moldy lint I saw on all those surfaces. In two cases, the main beam was decaying!