Penetrating roof -- what sealant to use?

I have to make penetrations in my roof for an attic fan and a vent cap for a bathroom fan. The bathroom fan vent cap installation instructions recommend using roof tar to put under the flashing and to seal the roofing nails. The attic fan installation instructions recommend pure silicon sealant for the same thing.

Any recommendations as to which I should use?

Thanks!

Reply to
Bob in CT
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I would recommend using what they recommend. I doubt if either is going to be a problem, but it is possible the materials used by each are different and the use of the other product may damage those materials.

Reply to
Joseph Meehan

What kind of roofing material is it? Is it asphalt shingles? If so you don't really need any sealer at all, just slide the flashing up under the shingles.

Reply to
Paul James

It is asphalt shingles. I think I'll still put a little sealant up there, just in case!

Reply to
Bob in CT

I have seen it recommended by the manufacturer for use with asphalt shingles, not so much to seal the opening as to glue the roofing tab down.

Reply to
Joseph Meehan

Are your flashings metal or plastic, if plastic most manufacturers don't recommend that you use any kind of tar based sealer. For metal if you have any nail heads showing it's a good idea to dab them with a little tar. I agree that if you break the seal on the shingles around your flashing a little dab of roof cement will stick them back down.

Reply to
Paul James

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