subject: Yurt Problems, Part Two [print this page] Yurt Problems, Part Two Yurt Problems, Part Two
As anticipated, we have experienced unanticipated problems with our yurt, during our first few months of living in this innovative, yet archaic home.
The most recent problem is that of condensation.
Our yurt is 28 feet in diameter, with a 28 degree roof pitch. It is insulated with R-6 fiberglass insulation in the wall assembly, and R-12 in the roof. Laid over this insulation, in the interior surface, is foil-coated bubble insulation, with an estimated R value of 3-5. The entire wall is sealed with foil tape, making it a vapour-proof structure. Similarly, the roof is lined with bubble insulation and taped. However, because of the joining of the roof ring and vent system, we are unable to seal the roof cavity entirely. Additionally, there is some inevitable movement of the exterior tarpaulin, which creates a convection of cool air meeting the light insulation layer.
During the daytime, sunlight on the roof often raises the temperature, during cool fall days, to a minimum of 10F above the inside temperature of the yurt. In the evening, moisture from our cooking, and moisture in the warm air (evening temperatures drop to about 30-40F lower than comfortable interior temperature) rises into the dome cavity of the yurt, and is trapped there. The vent, used to great effect in the summer, cannot be opened on cool fall or cold winter days.
As a consequence of dropping outside temperatures, the tarpaulin canvas accumulates excess condensation on the inside and outside of the fabric, which drips for hours as the air cools. The moisture in the warm interior air now conflicts with the cooler surface of the lightly insulated tarpaulin, and forms condensation which drips throughout the living space (there is nothing quite so "stimulating" as icy water dripping on you during a sound sleep!).
To resolve this problem, we have installed four 12volt min-fans near the surface of the ceiling area. Drawing less than 6 watts (at 12 volts), they run all night without a noticeable rain on our batteries, drive a small amount of the warm air at the apex of the building downward, and keep the condensation under control.
In the past week, we have experienced only modest condensation within the yurt. However, exterior condensation still exists. Next week, we will be installing insulation in the roof vent cavity, covered by a foil "liner" and taped with foil tape. This should seal interior air from contact with exterior air at the roof line, and eliminate the condensation issue.
