Once the walls of our yurt and the roof rafters were in place, there was a strong urge to apply the tarpaulins, just so we could see the “finished” product. However, several preliminary steps were required, to ensure that the treated fabric would last, that the building was wind- and rain-proof, and that the structural integrity was intact.
Hurricane ties were installed on the outer end of each rafter, in addition to the two screws holding the rafter ends in place. Although wind resistance is minimized with the circular design, screws are insufficient to provide the strength needed, as screws have a tendency to shear. In fact, in most jurisdictions, screws are not acceptable, according to the Building Code, for framing.
Hurricane ties were also installed on the roof ring end of the rafters, as a secondary support for the six-inch bolts securing each inner rafter end.
To reduce lateral sway, crossties were installed, earlier, at approximately the midway point of each rafter (see prior blog posts).
Where screws extruded from each plate joining the two-foot wall segments, the ends of the screws were treated with latex caulk, to reduce rub friction against the inner layer of tarpaulin.
At the top edge of the roof ring, we fastened a rubber edging, to prevent rubbing of the tarpaulin against the sharp edge of the ring. We used a rubber molding from an old automobile windshield, fastened with roofing nails to the ring.
Lastly, an inner layer of tarpaulin was secured around the perimeter and on the roof of the yurt. These tarpaulins provide an additional rain and barrier, but, more importantly, act as a buffer between the final, outer tarpaulin layer and the framing. The tarps cost less than $90 each, and should extend the life of the outer tarpaulin by 3-5 years (a cost saving of more than $1,600).
Just as in conventional buildings, caulk was applied around the windows and door, and drip mold & j-channel framed the openings.
One additional feature that we incorporated into the design was a roof-top vent system, to improve air flow. This vent was constructed (see picture) of osb, and oriented in a north/south direction, so that the vent windows can be opened on either (or both) end(s) to maximize ventilation.
In our next post, we will discuss finishing touches and exterior tarpaulin application. The following article will provide information on interior finishing stages. The last three articles will provide information on setting up our solar, wind & biomass energy systems, as well as our grey water recovery systems.
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