roof flashing

[Charles2]

If you are installing a double-wall chimney pipe up through a roof covered in asphalt shingles, but you think the roofing might later be changed to standing seam metal, does it make any difference in how the base of the chimney ought to be flashed?

 

[begreen]

I'd probably replace the flashing when and if the roofing changed

 

[Highbeam]

If you are installing a double-wall chimney pipe up through a roof covered in asphalt shingles, but you think the roofing might later be changed to standing seam metal, does it make any difference in how the base of the chimney ought to be flashed?

No. You'll get a whole new flashing when the new roof material is installed. The hole in the decking is the same regardless which is to be 2" bigger than the pipe OD.

 

[SteveKG]

Ditto on installing new flashing with a new roof. You "can" sometimes salvage old flashing, but it is usually bent up a lot and has a lot of dried-up or sticky sealant. That sealant needs to come off and is a bear to do. I've done it both ways, and I'll never try to re-use old flashing again. It is really worth the money to have easier installation plus reduced chance of a water leak.

I tore off the cedar shingles on my roof and went with standing-seam metal. I attempted to re-use my old flashing in that particular case and it was a lost cause. Plus, the flashing for standing-seam roofs is sometimes a bit different in that one can mold the edge of it across the seam(s). If you are lucky enough to have the stovepipe come out of the roof in the center of a steel panel [equidistant between two standing seams], you can often use regular flashing. I wasn't so fortunate. Plus, trust me, the old flashing will be a mess when you remove it to re-roof.