Hurricane ties
Trevor_Lambert
| Posted in General Questions on
I was going to use hurricane ties for roof trusses on my workshop. They’re not required by code, but I figured for about $100 in materials, why not? The framer I’ve contracted to install the trusses thinks they are unnecessary. I get the impression he’s not too enthusiastic about using them, probably because I imagine they require hand nailing rather than a nail gun. He’s technically correct, they aren’t necessary, but am I correct in thinking it’s a worthwhile upgrade?
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Replies
Use timberloks, really fast install
You can use a nail gun to attach connectors like hurricane ties, you just have to use a "positive placement nailer" such as this model from Paslode:
https://www.homedepot.com/p/Paslode-Pneumatic-30-F150S-PP-1-5-in-Positive-Placement-Metal-Connector-Air-Tool-Framing-Nailer-515850/314572454?source=shoppingads&locale=en-US&srsltid=AfmBOopoynB0Xm9gk9wxHmsLXVuPD3_mq32HZrIPECLo40KfuoKTj3tGGQY&gQT=1
Note that there are plenty of other similar products that can do what you need. The "positive placement" part is basically a special tip on the nailer that makes sure you can get the nail into the hole in the steel strap part of the connector.
That said, the purpose of hurricane ties -- and there are TWO PARTS to them (one ties the rafter/truss, top plate, and stud together, the other ties the stud, sill plate, and foundation together) is to resist uplift forces that are created by high winds. The idea is to keep the structure tied together so that it can hold up better in high winds. Without hurricane ties, you have forces acting to pull nails straight out, not unlike the force exerted on a nail when removing it with a hammer's claw. The hurricane ties put the forces on the nails in shear, where they have more resistance to pulling out of the wood framing members.
Bill
Trevor,
Definitely worth it. Cheap and fast to install. As Bill said, most framers have positive placement guns for joist hangers. I use a palm nailer.
Several manufacturers also make truss screws that serve the same function.
https://www.strongtie.com/strongdrive_interiorwoodscrews/sdwc_screw/p/strong-drive-sdwc-truss-screw
I use a palm nailer too, since I don't nail these things often enough to justify buying a postive placement nail gun. It's worth mentioning that you MUST use the nails the manufacturer specifies when attaching connectors. If you use some other kind of nail, the connector's listings/ratings are invalid.
Bill
Not required, specifically, in some municipalities. But uplift resistance is required, and how much depends on your design standard. Basically, hurricane straps (or screws) are standard construction these days. Cheap and easy to install. What else does your framer think is unnecessary?
I've got both the short and long (1.5 and 2.5 inch) Senco positive placement nailers (the shorter was for a specific project for joist hangers), and they work fantastic. Nothing that can't be done with a palm nailer; pos placement nailers are just faster and easier.
Honestly, I'm probably going to get the Simpson truss screw system for the next building I do, because it sidesteps some air sealing and drywall headaches that can be caused by standard hurricane ties. Still debating that one though.
Put a hurricane strap on a truss or solid rafter, and you'll be shocked at how much more solid they are then code-minimum toe nailing, etc.
So the consensus is that the hurricane ties (Simpson H1A) are better than the Timberlok screws?
If so, is there any reason I can't install the ties myself after the fact?
Trevor,
Truss screws are designed slightly differently than similar general structural screws like Timberlock and GRK RSS, in that they have continuous threads throughout their length. I would use one made specifically for this purpose. These are very similar to the Simpsons:
https://www.camofasteners.com/products/screws/structural-screws/truss-screws/
No reason you can't do it yourself once the trusses are up.
The TimerLok ones claim to be for trusses, if you look at the 6 inch ones. They have specs for uplift and sheer resistance. I'll see if the Camo ones are for sale anywhere.
Timberloks are specifically designed for rafters and truss tie connections and are not a general structural screw according to fastenmaster. They even make a specific install tool that aligns it with your rafter
freyr_design,
You are right. I missed those ones!
Trevor,
I don't think there is much to choose between any of them. I'd buy whatever was available near you, and cheapest.
You need something to prevent truss uplift. The options all have different load ratings for their resistance to uplift forces. I calculate what is actually needed and spec whatever is appropriate. Often that's a truss screw, installed per manufacturer's instructions. In other cases it's an H2.5A which is usually more than enough in my area, even though it only fastens the truss or rafter to the upper of the two top plates. On rare occasions I use one of the heavier-duty options.
I believe the ties are stronger compared to the screws. You can look these up on Simpsons technical data on uplift for the ties. But just going on feel, If you've ever seen fastener pullout test on YouTube, a screw in pine isn't the most robust. Vs a hurricane tie that uses 8 x 8d nails in shear. And if you want more stability in addition to the uplift, I think the H1 ties are good for that.
I have a mcn nail gun, so metal connectors are no big deal for me. Obviously the screws are easier and I expect are still a good solution if you make sure it's above your uplift loads.
Fasteners go through rigorous testing and the math is pretty simple. Going by "feel" for something like this is silly when accurate data is easily accessed.
Here is the data for Simpson truss screws, with options for different types of wood and different types of loads: https://www.strongtie.com/strongdrive_interiorwoodscrews/sdwc_screw/p/strong-drive-sdwc-truss-screw.
Simpson H2.5A "hurricane clips" have roughly similar values: https://www.strongtie.com/seismicandhurricaneties_strapsandties/h25a_htie/p/h25a.