Running Wires Across A Rooftop?

Scottyk

Was hoping someone had some advice. I need to pull low voltage siamese cable across a flat tar commercial rooftop. I rather not run the wires across the roof, but I dont have any other choice. Pipe in EMT or PVC? I dont want to use fasteners <dont want to cause any leaks> so use Tar or another adhesive to strap pipe?

copusbuilder

E.M.T. with raintight connectors strapped to blocks tarred to the roof was the norm a few years back. You might not need the raintight if your wire will survive outdoors.

The roofers used to set the blocks so not sure how they would feel about you setting them?

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Slyfox

If you run your pipe good, making sure your fittings are tight,
you won't need to fasten the blocks to the roof, just fasten the pipe to the blocks and leave the blocks loose layed.
We always suggest 4x4 blocks, but have used 2x4's.

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We Fix Houses

Try laying out some 2" (less weight) or 4" thick 8" x 16" cinder block and running conduit across them. Fasten with straps and tapcons. Include a loop or two of liquidtite so it can be moved a bit.

Scottyk

Thanks for all the great ideas, much appreciated. I like the cinder block idea so i dont have to break out the tar. Is there any drawbacks to using objects as heavy as the cinder blocks on the roof? I need to run 160' of pipe. How far apart should I place the cinder blocks / standoffs? If i dont tar them down... do i need to worry about extreme high winds possibly blowing the pipe off the roof?

MALCO.New.York

DO NOT use CMU's on EPDM. I prefer to NOT use CMU's on any roof that is not a "Built-Up".

As far as the spacing.......Depends on the "Roof Traffic".

On a non-residential building, 4 inches (or there abouts) past EVERY coupling. EVERY coupling! DO NOT put the supports directly under the Couples. Mid-span if really concerned. (although redundant)

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RoofGod

Just use treated 4x4 pieces every 4' or so with the pipe fastened to the wood blocks and set it on the roof. No tar or anything. It wont blow away.