Lead flashing for 3" stink stack -- sealant required?

Just up-sized my plumbing venting so that it now has a 3" vent going through the roof.

I had a roofer install a lead flashing (with lead counter-flashing cap) for me. He nailed it along the top edge (under the shingles), but did not use any sealant/roofing cement/anything. He said the weight of the lead would keep it in place and it would be able to move slightly to accommodate thermal expansion of the horizontal ABS piping below (the 3" ABS 90's just below the roof).

From the inside of the attic, I could see sunlight around the cutout, so I went up on the roof and pressed the lead flashing down flat against the roof. The jostling of the pipes during final hookup must have bent the flashing.

Before I seal up the ceiling below, should I be making another trip up onto the roof to apply some sealant?? If so, what and where?

Roof is 8/12, fiberglass shingles, over skip-lath and OSB.

Thanks!

You shouldn't need sealant but that's not to say it won't hurt.

It normally will not leak unless you have a "driving rainstorm".

Yes by all means if you can see sunlight then water will flow !

I use henrys #208 roof mastic

MACPLUMB 777 said:

Yes by all means if you can see sunlight then water will flow !

I use henrys #208 roof mastic

Click to expand...

Thanks -- where would I apply it? Under the lead base? Top side of the lead base between it and the shingles? Somewhere else?

Here's a picture of it once I flattened it back down flush with the roof (8 in 12 slope):



The lead base is currently nailed along the top edge (under the shingles).

Thanks!
.../j

I would do around the bottom edge and where the pipe comes out though the flashing

what these plumbers in the southwest don't know is how much constant rain you in

the great northwest get,

i spent 5 years there so i do know that you get a avg. Rainfall

of at least 18 - 20" a year and the way the wind blows it can come in anywhere !

MACPLUMB 777 said:

I would do around the bottom edge and where the pipe comes out though the flashing

Click to expand...

There is a lead counter-flashing cap on this assembly that comes down inside the plastic ABS for 1/2" or so. Is that where you mean by "where the pipe comes out through the flashing"?

And, by "around the bottom edge", do you mean under the lead flange?

You're right -- we get 50mph winds with driving rain at least a few times a year... want to make sure there are no surprises after this is all closed up....

If the flashing go's over and into the pipe no problem !

You just don't want to be able to see daylight !

Yes i was talking about the lower edge of the flashing on the shingles