In other words you ve got a leaky roof.
How much charge replace pipe boot roof.
And the simpler the roof the simpler the repair job.
The more squares to be repaired the higher the cost.
If built up or membrane roofing probably more like 100 per location minimum on up to as much as 200 each depending on roofing type some are a pain to get right and require several layers of sealing and roof repair to replace and of course if built up roofing commonly requires hot tar use also so prep time and cost on that.
A detachable plastic metal or rubber vent boot seals the vent pipe to prevent a leaking roof water stains moisture damage.
If not replaceable or can t get the replacement boots then the entire roof jack the sheet metal cone with the boot and flat metal base has to be replaced which means it has to be pulled out from under the overlying shingles and off the duct that connects through it and typically that means removing about a 3 5 foot area of shingles because.
Roof valley replacement cost roof valley replacement costs 200 to 850 depending on the length slope of the roof type open or closed and the number of shingles replaced.
If you have a friend that can climb a ladder it would be much cheaper.
If your roof boot moves or is damaged in some way it can allow water to penetrate your roof.
And in order to calculate how much repairing your roof will cost you you need to understand these factors.