I'm having a new roof installed and the roof vent is cast iron with some kind of lip on the end which won't allow a standard roof flashing ring to go over it. Can I cut the cast iron w/sawzall below the roof line about 3 feet and transition to pvc through the roof to allow a proper flahing kit to avoid further leaks.How high above roof must the pipe extend and can I use a 4 band clamp for the connection. I live in Massachusetts. Thanks for your help.

Hi Neighbor...

YUP! Cut the cast iron with a sawzall as you suggested and install 2 band PVC x cast iron MISSION COUPLING (see image) to stay within code requirements although I think the 4 band clamp you suggested actually makes a better seal as it has the 4 bands... ;)

Lennox makes a great DIAMOND sawzall blade that'll cut that cast iron in 5 minutes if you can find it. Republic Plumbing Supply Company has 9 locations throughout Mass. so could check with them for all your needs.

Welcome to Republic Plumbing Supply Co.

They'll have a proper size roof boot, too... see image.

The vent needs to terminate 18"-24" above the roof line... depending on your city/town inspector.

Good luck!

Mark

I think to be precise about height you need to know your pitch; the steeper the pitch the higher the vent must be, and it depends too on proximity to a chimney.

Hi joypulv...

As noted above, a vent that penetrates a roof in Massachusetts must be between 18-24" above the roof line... because of snow.

Pitch of the roof and proximity to a chimney have nothing to do with it here in Mass. Anyway.

Proximity to a SKYLIGHT, on the other hand, is a concern and the vent cannot be within 10 feet of that... ;)

Mark

Check with your local Building Department for code on the height of the vent from the roof line.
Marks code calls for between 18 and 24 inches while our code allows 6" above the roof line. The difference being that Mark lives where it snows and I live in Florida.
And how is your ttemperature today? Tom

Hey Tom...

Amfrugal is from my state... why I answered the question so specifically... ;)

Have a great day!

Mark

Thanks Mark I missed that part. My code also mandates that if you live in a frost area, Brrrr!'That all vents smaller then 3 inched be increased to 3" in the attic before exiting the roof. ( SPC-- 1405.1 and 2 (Frost Closure) So far when haven't had to do that in the Tampa Bay Area. Cheers, Tom