Fastening Light Gauge to 5/16" Steel

[DHKpeWI]

I need to determine what screws should be used to connect a 5/16” plate to light gauge rafters and roof trusses. See the attached sketch. The wind uplift is around 80 pounds/foot. The 5/16” bent plate will support a gutter, which will weigh 16 pounds/foot if full of water. The building is in Florida.

What screws would you use in this application? If installed from above, the screws will go through the 5/16” plate first and then the light gauge. Hilti has a self tapping screw (S-MD 12x24/1-1/4 HWH #5) that will provide plenty of capacity. Have you specified this screw for this application? Did you get good results? Could the screws be installed from below?
Thanks

 

[MiketheEngineer]

Never used those - but I do believe in just about everything Hilti says and does. They are a good vendor. Check with them.

 

[woodman88]

I have/would never structurally attach a light gage metal to a steel plate with a self tapping screw from the steel plate side. I would be very interested in what Hilti says about doing this, for possible use in the future.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[DHKpeWI]

I spoke with the Hilti engineer, and he sindicated that the self tapping screws would work when drilled from above. He recommended using 14 gauge or 12 gauge material.

 

[dik]

I've used the Hilti fasteners and they are good... also depending on use I use TEKS3 and TEKS5 fasteners...

Dik

 

[ash060]

I would follow the calculations for pullout using the AISI equations, But 80#/ft is not that much.

 

[DHKpeWI]

Thanks everyone for your help!