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Roof Framing for Hurricane Safety with Reflective Sheathing for Energy Savings
computer-generated transcript - may not be 100% accurate
" -Okay, so we're sheathing the back of this roof and joining me is Brian Redling from the APA Engineered Wood Association, whose gonna help understand a little bit about the new technology to some of these materials. We're looking at the clips, Brian, there are on the rafters as they join the top plate of the wall."
" -Right."
" -And that's these little things here."
" -Yeah."
" -What's the purpose of these?"
" -Basically, that enables us to load the nail, instead of pulling the nail out like a traditional toenail, these clips act to shear the nail off or shear the head of the nail off, which a lot more strength than just simply pulling the nail out."
" -Exactly, the nail is driven in horizontally into 2 wooden members, either down to the plate or down into the raft and that gives more strength and when there is a hurricane situation and that lift is trying to bring the roof off of the house, this will prevent it."
" -Right."
" -Or will help to prevent it."
" -That's all the part of our continuous load path that we need, all the way from the top of our roof, all the way down to the foundation."
" -Right. We've looked at other aspects of it along the way. Now, the TechShield is a product that we're using to sheath the roof, but it's essentially a plywood with a reflective surface and I've got it upside down here, so that we can look at it, but this will be flipped out and the reflective surface faces the attic space. Now, this is a hot-weather product. This is not something that's designed for cold climates, but rather for areas where you can reduce the amount of heat gain into the attic space by up to 30 degrees because this will actually act as a mirror, it will radiate the heat right back through the plywood and shingle and won't let it get in to the attic space, so it's a real energy saver."
" -What about, how it should be attached Brian?"
" -Attachment of roof sheathing in a high-wind area like we have here is critical. A low-slope roof, the lower the slope, the more uplift you have. And in this case, we would recommend a ring shank nail be used because of the additional withdrawal capacity."
" -Right."
" -And that will be located at 4 inches on center along the end of the panel and 6 inches on center along the intermediate framing member."
" -And the point of the ring shank is a little bit like a screw, it's not quite a screw, but it does grip and it won't slip back out of the wood."
" -It has a lot more withdrawal value than the smooth shank nail. "
" -Right, and what about adhesives? Do we recommend the use any kind of panel adhesives on the sheathing? "
" -We don't really recommend the use of an adhesive because that tends to squeeze out in the panel joints. We like those joints to maintain a 1/8 of an inch space, so that the panels can expand, more or less an expansion joint."
" -Uh huh."
" -With adhesive in that joint, kind of restraints the panel from expansion."
" -However, as I understand it, the sheathing system of a roof in a hurricane can still keep a lot of water out and most of the damage in a hurricane is from water, right?"
" -Right. Insurance industry studies have shown that once the roof coverings or the roof sheathing of lost and water comes in to the building, we've lost about 80% of the total value of our structure and its contents. One of the products that kind of being seen more and more is this peel and seal about 10 minutes membrane, that's stuck across the panel joints to keep the rain out if the roof covering is lost. This seals the joints of the plywood or the OSB said that water doesn't between the joints and into your house."
" -Uh huh. Now, the fact that they have a shinny side on it is totally coincident, it has nothing to do with a shinny side on the TechShield."
" -No."