2 In determining crawlspace surface temperatures we can pretty much ignore the ventilation air change. We don’t get much ventilation air change in crawlspaces-the typical ventilation air change rate in a crawlspace is approximately 1 air change per hour (ach). And who cared if the ground or the ground cover was wet as long as the wood framing was not. In the good old days this was the ground-or the ground cover which of course is at the same temperature as the ground. In an irony not appreciated except by building science geeks ventilation air in the summer months in most parts of North America brings moisture into crawlspaces and deposits this moisture on surfaces that are below the ventilation air dew point.
The ground in crawlspaces is cold, 1 much colder than the outside air during the summer months. No one had heard of vinyl flooring yet.įigure 1: Old Crawlspaces-Old uninsulated and ventilated crawlspaces had warm floor assembly surfaces due to heat flow downward from occupied space above. This was a pretty big deal as the temperature of the floor framing was above the dew point temperature of the exterior air that was used for “ventilation.” And the old floor finishes tended to breathe-they were relatively vapor open. Everywhere, even in air-conditioned buildings. Why? The floor framing was pretty much always warmer than the ground ( Figure 1). They were ventilated and they didn’t have ground covers-and they didn’t have problems. Think of the good old days-the Civil War, WWI, the Great Depression, WWII-crawlspaces were uninsulated. Photograph 3: Ventilation Opening-Crawlspace has plenty of cross ventilation and good drainage. Photograph 2: Nice House Over Icky Crawlspace-This house with the crawlspace problem is in Washington, DC Photograph 1: Icky Crawlspace-Note the condensation on the underside of the fiberglass insulation and the rot at the exposed portions of the crawlspace floor joists. What caused this mess? The floor insulation.
#Walking papers light below vinyl code
Everything in this crawlspace was done “right.” It has code specified ventilation, a continuous impermeable ground cover, excellent drainage and still we have a mess. Did I mention that this is a vented crawlspace ( Photograph 3)? Oh, by the way, there is a continuous plastic sheet ground cover and excellent drainage. The house over this crawlspace is not shabby ( Photograph 2). The exposed wood floor joists are rotting. Photograph 1 shows the modern crawlspace, which is a forest of water droplets on the underside of fiberglass batt insulation.
Crawlspaces stink, they rot, and are just plain icky.
0 kommentar(er)
