some time ago I was digging around and came across a web site that advertised massive gains in structural strength. Key to their proposal was the use of Kevlar tape.
Used in place of a collar tie the rafters would be set and a length of Kevlar tape would be temporarily fastened in place up the edge of one rafter, across the ridge board and and down the corresponding rafter on the other side. Then the roof deck would be nailed down in the normal manner. The Kevlar firmly clamped and with numerous nails through it would hold the roof deck and rafters together at the ridge line.
I was looking at this sort of thing thinking that it was a really neat idea. Reinforcement that can be nailed anywhere. Not just in the little holes. Where the reinforcement doesn’t block nailing when the next layer is applied. A reinforcement that gets stronger the more layers applied over it and nails shot through it.
I got looking around and found Kevlar tape that seemed about right, loose weave, 1/16″ thick and 2″ wide so you can get a little sloppy on placement. Found some at about $1 to $2 per foot. The price goes down with bigger orders of course.
It would be nice if it cam self-stick. Slap it on and lay the deck.
Perhaps a bead of PLPremium on top and underneath the tape would help. Be messier. The weave is pretty open.
I was thinking it would be great reinforcing the Stud- top plate- rim joist- bottom plate- stud junction between floors.
You could eliminate a lot of structural reinforcements. I’m thinking of ways it might be used to replace hangers.
What do you think? Will we be seeing Kevlar tape on job sites any time soon? Good idea or lunatic ranting?
What do you think.
Replies
Unless they have developed a treatment for it, the longevity is in question. moisture weakens Kevlar over time.
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I'd question the strength of the Kevlar when used in this fashion. If all you're looking for is to tack stuff together while it is going up is one thing, actually looking for structural improvements when compared to steel clips and the like is another.
It's all in the weave. As with any anisotropic material, you have to pay close attention to where the fibers point vs. where the load is. Point the fibers in the wrong direction and the whole thing may fall apart. Another thing to avoid are point loads, so I hope you can remove sharp corners and other hazards that'll significantly reduce the stress-capability of the fibers.
Then there is the question of how to bond it well with the underlying wood. I wouldn't trust nails to do it. For me, polyester, vinylester (or better yet, epoxy) are the only methods I would use. You can still nail through all that, but setting up a proper curing station for these materials is tricky, particularly in the kinds of environments found on construction sites.
Lastly, wherever you take this idea, I wouldn't focus just on Kevlar. There are many kinds of fiberglass, and E-Glass, S-Glass, etc. are a whole lot less expensive than Kevlar and may give you similar performance in this application.
In my estimation, the quickest way to improve the structural rigidity of anything is to put away the Paslodes and require folk to use properly-sized screwguns.
Somewhere someone was marketing large kevlar straps that were to be run from one sill, over the top plate, across, and down to the sill on the other side. Sort of a whole house hurricane tiedown. It was to be placed over the sheathing/under the siding. I want to say they were 4 inches wide, though I cannot remember for sure. They could be nailed through as needed, so they did not interfere with standard construction techniques. This was 8 or 9 years ago when I was designing a coastal home. Didn't use them.
Reminded me in concept of the old coastal homes in Maine that are held down with steel cables, though these are unseen.