Roof Vent Replacement, Pipe Boots and Flashing Repair
Cracked plastic box vents, sun-split pipe boots, a bath fan blowing into the attic — the small roof jobs that cause big leaks, done in one visit at a per-unit price.
JMB Builders replaces roof vents, pipe boots and flashing on asphalt shingle roofs across the Twin Cities metro, and installs new roof caps for bathroom fans, range hoods and dryers that were venting into the attic. Each vent, boot or cap is priced per unit, so a roof with three cracked plastic box vents and two split boots is one quote. Quoted from your photos within one business day and done in a single visit.
- Priced per unit: vent, boot or cap
- Bath fan and range hood caps ducted through the roof
- Quote from photos in 1 business day
- Licensed MN contractor BC809005
Everything that sticks through a roof wears out faster than the shingles around it. Plastic box vents go brittle and crack. The rubber collar on a pipe boot splits. A bath fan cap loses its damper flap and birds move in. A furnace flue collar rusts. None of these is a roof replacement, but each one is a leak waiting for the right rain, and a lot of roofers will not come out for one vent. We will, and we price it per unit so replacing all of them at once is a straightforward number.
The other job on this page is venting things that should have been vented years ago. A bathroom fan that dumps into the attic wets the insulation and grows frost on the sheathing every winter. A range hood or dryer run that ends in the soffit pulls the moist air right back in at the soffit vent. We cut the roof, set a proper cap with a damper on ice and water membrane, and connect the duct with an insulated run so it does not drip condensation back into the fan.
Any of these can be done on their own or added to a leak repair or a full reroof.
What you supply
- Photos of the roof from the yard showing the vents and pipes, plus a close-up from a ladder if you have one
- For a new fan or hood vent: a photo of the fan or hood and where the duct currently ends
- The fan itself if you are having a new bath fan installed; wiring beyond swapping a fan in place goes to an electrician
What JMB supplies
- New pipe boots (rubber or lead-free metal) set on ice and water membrane under the shingles above
- Metal box vents, turtle vents or ridge vent to replace cracked plastic, re-shingled around
- Roof caps with dampers for bath fans, range hoods and dryers, cut in and flashed
- Insulated flex or rigid duct from the fan to the cap, strapped so it drains toward the cap
- Step, counter and kick-out flashing replaced where it is missing or caulked over
- Furnace and water heater flue collars and storm collars
- Photos of each finished unit in your job folder
How it is priced: per unit
Quoted in writing from your photos within one business day. What moves the number:
- Swap in place (boot for boot, vent for vent) vs. a new cut through the roof and duct run
- Roof pitch and height; steep roofs slow every unit down
- How many units on the same visit; the trip is shared, so each added one is cheaper
- Length and route of a new duct run through the attic to reach the cap
- Flashing repair that means lifting more shingle courses, such as a sidewall or chimney
- Whether the shingles around the unit are brittle and have to be replaced in a wider area
Count the pipes and vents in your yard photo and tell us which ones are leaking or look cracked; the quote lists every unit separately.
How long it takes
Boots and box vents: an hour or two each, several in a morning. A new bath fan roof cap with duct: half a day. All of it in one visit.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized quote within one business day. We only come out to measure first when the job needs a tape measure — no pressure, no games.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Pipe boot replacement
The plumbing vent stack boot is the number one leak. New boot on membrane, shingles above lifted and reset, sealed at the collar. We can fit a boot with a metal collar that will not split again.
Box and turtle vent replacement
Plastic box vents crack at the corners and at the nail line. We replace them with metal vents of the same footprint so the shingle cut does not change, or swap several for a ridge vent if the roof and intake support it.
Bath fan roof vent install
A fan venting into the attic or the soffit gets a real roof cap with a damper, cut in through the sheathing and flashed under the shingles, with insulated duct back to the fan so it does not sweat and drip.
Range hood and dryer roof caps
A larger cap with a backdraft damper for kitchen hoods and dryers when a wall exit is not possible. Dryer runs get smooth metal duct and a cleanable cap, not a screen that clogs with lint.
Flashing repair
Missing kick-outs, caulked-over step flashing, rusted valley metal or a storm collar that has slid down the flue. We replace the flashing the way it should have been done, tucked under the shingles and behind the siding.
Roof Vent Replacement, Pipe Boots and Flashing Repair: questions, answered
How much does it cost to replace a roof vent?
We price each vent, boot or cap per unit and list them on the quote. What moves the number is whether the vent is swapped in place or newly cut in, how steep the roof is, and how many are done in the same visit. A roof with several to replace is far cheaper per unit than a trip for one. Send a yard photo and you have the list the next business day.
Can a bathroom fan vent through the roof?
Yes, and in a story-and-a-half or a hip roof house it is often the only sensible route. The cap needs a damper so cold air does not fall back down the duct, the duct should be insulated so warm moist air does not condense inside it, and the run should slope toward the cap. Venting into the attic or ending at a soffit vent is not an option; both put the moisture right back into the house.
How do I know if my pipe boot is leaking?
Look at the rubber collar where the pipe goes through the boot. If it is cracked, curled away from the pipe or has a gap you can see daylight through, it is leaking or about to. Inside, the stain shows up on the ceiling below the pipe, often near a bathroom or kitchen since that is where the plumbing vents are. A new boot takes under an hour.
Should I replace all the roof vents at once?
If one plastic vent has cracked, the rest are the same age and going the same way. Doing them all in one visit shares the trip and the setup, and you stop chasing them one leak at a time. On a roof that will be replaced within a few years we may tell you to wait and do them with the reroof instead.
Do you install the bath fan too, or just the roof vent?
Both, if the new fan replaces an old one in the same box on the same circuit. We set the fan, run the insulated duct and install the roof cap in one visit. A new fan where there was none, or a new circuit or switch, needs a licensed electrician for the wiring; we will coordinate the timing so the roof cap and duct are ready when the electrician is.
Can you add a ridge vent instead of box vents?
Yes, if the roof has a ridge long enough and the soffits provide intake to feed it. We cut the slot along the ridge, install the vent and cap it, and close off the old box vents so the ridge vent does not just pull air from them. If the soffits are closed or blocked we tell you first; a ridge vent with no intake does nothing.
Get a written quote for this job
Three photos and a sentence is enough. You hear back within one business day. Or text the photos to 763-204-2099.
Related jobs we do
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Ice dams, a furnace that never shuts off, a bedroom that is cold at the ceiling: the attic is the first place to look and the best payback in the house when the air sealing is done before the fluff.
Read moreFascia Board Repair & Soffit Section Replacement
The gutter is pulling away, the fascia behind it is black and soft, and a soffit panel is hanging down. We replace the bad section, fix what caused it, and put the gutter back where it belongs.
Read moreChimney Flashing Repair — Step and Counter Flashing Rebuilt
A stain on the ceiling next to the fireplace, wet brick in the attic, a ring of roof cement around the chimney — the flashing rebuilt in metal, cut into the brick, so it stays fixed.
Read morePage reviewed September 24, 2026 · JMB Builders LLC, MN license BC809005 · All roofing pages
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