We use Velcro plates for attaching just about anything. For roofing, they work great as a platform on which to secure rafters, vigas, or trusses. Their main function is to distribute the weight of the individual roof members to keep it from digging into the earthbag wall. The plate is attached to the roof member prior to being lifted onto the wall. When the roof member is correctly positioned, the plate is Velcroed into place with three-inch (7.5 cm) long galvanized nails.
The Velcro plate alone is not enough to secure the rafter. The rafter needs to be anchored firmly to the wall to prevent uplift from wind blowing up underneath the eaves. Rafters can be secured by banding or strapping that has been installed three to four rows below the top row of bags. The strapping itself is installed during construction (Fig. 9.11a & b on page 115).
In addition to the tie-down method, another row of bags can be placed atop the Velcro plates in between the rafters. Besides adding additional anchoring to the Velcro plate system, the bags fill the spaces between the rafters up to the level of the roof itself. The bags
9.9: This Anasazi structure in Chaco Canyon, New Mexico, shows the original vigas and latillas sitting on stone and mud walls, still intact after 1,000 years. Will a modern tract house ever get to make this claim?
CHECKLIST FOR SUCCESS
Combine all of these features:
• Provide adequate solid wall in between openings.
• Keep the openings relatively small.
• Integrate interior walls and/or buttressing.
• Keep roof spans short or build internal supporting walls or post and beam structure.
• Choose a roof design that exerts pressure downward instead of outward.
also provide each rafter with lateral support. Any of these tie-down systems can be used for trusses and vigas as well (Fig. 9.12).
9.10: Examples of roof styles suitable for earthbag buildings.
flat ccding truss
rafter bolted to Velcro plate with steel bracket, Velcro plate cinched tight with banding rope over notched rafter cinched through exposed ends of a loop of and 3/4"poly pipe in rafter set into wall overlap and twist ends overlap and twist ends
9.11b barbed wire "haJos" resemble a
9.11b barbed wire "haJos" resemble a after laying a whole row, gently tamp bags in between rafters as a dirtbag substitute for wood blocking nailing halos of barbed wire in between rafters creates a mini tension ring
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