Fastener Conundrum: Snow Cables

[toxcrusadr]

If you've been to snowy places you've seen the cables strung horizontally along metal roofs to prevent sudden mass unloading of snow. They also use cleats. I need a similar thing for my shop building. It's 35x85 so a lot of roof to cover. I figured out a cheap solution: 100' rolls of stainless steel braided cable from Harbor Freight. But how to fasten it an inch or two above the roof while preventing leaks around the fasteners?

I thought of using a screw eye into the wood truss. The special screws used to hold the sheet metal on are a hex head with a built-in rubber washer with a metal washer over it. When you screw it in, the rubber washer seals the penetration.

I could use an eye bolt, rubber and metal washers, and a nut to tighten it all against the sheet metal, but an eye bolt has the wrong threads for wood. If I used a screw eye with wood screw threads, there's no thread to put a nut on to compress the rubber washer.

I wonder if a dab of silicone caulk is enough to seal up these penetrations. I don't want to create leaks in my roof, I got enough problems already with the snow. Including a destroyed gutter and a broken window (from a mass unloading of 15" a couple years ago).

Thoughts?

 

[BillWojo]

Do you know any smaller precision sheet metal shops in your area? Maybe they could shear some 14Ga stainless steel, punch 2 holes on one side and 1 hole on the other side. Bend it in the middle to form a piece of angle, similar to angle iron. The 2 holes will be used to fasten to the roof, use roof mastic under it for sealant and the single hole to thread the cable through. Not sure how high the cable needs to be off of the roof and how many supports you will need to keep the cable from sagging between supports. It would take a substantial structure at the ends if you try and tension the cable, but I wouldn't think it needs that.
Talk to the shop owner, let him know it's a cash job and your not in a major hurry. They may have scrap cutoffs that came from a job (already paid for) and if they are not busy may take it on as beer money. Worth a shot.

BillWojo

 

[BigElCat]

Just use 1/8" x 1" flat bar. 10" long. Stick them up between the gutter and the facia. Attach them to the facia. Use eye bolts, or weld washers perpendicular to the flat bar. If the cable retainers are welded to the flat bar, you'd have to stick them in from above. You'd need a double row of the cable.

No chance for roof leaks. Least expensive that I can think of.

You might want to run a screw in up high in the gutter itself for each flat bar. That way, if the flat bar would start to bend, the bend would be above the gutter. The cable fence would lean out over the gutter, rather than pull the gutter off.

The roof over-hang presents a challenge to this idea. You'd almost have to take the gutter down to do the install. Trim the over-hang for each flat bar, bend it down so the newly created tab is sandwiched between the flat bar and the facia. Then put the gutter back up.