I recently came across a plumbing vent flashing repair device that looked like a cross between a two-piece plumbing vent cap and Darth Vader's helmet.
Easy fix for split boots on plumbing vent flashings
Includes Screws, Hex Driver and Gloves for Installation #1 Fits 3/4 to 2-3/4 Pipe OD, #2 Fits 3/8 to 4- 1/2 Pipe OD, #3 Fits 2 to 7 1/4 Pipe OD
EAGLE 1 EPDM Flexible Roofing Pipe Flashing Retrofit Split Zipper Boots - On Site Adjustable Roof Pipe Jack Boot with Round Base (Multiple Sizes) (No.
DEKTITE® 0 - 5 Retrofit Split Boot Roof Vent Pipe Flashing at
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Vent Flashing Done Right - Fine Homebuilding
An easy fix for split boots at plumbing vent flashings
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Roof Flashing, Roof Jack, Chemcurb, Pipe Jack, Lead Flashing, Pipe