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Remove a metal chimney flue or vent pipe.

Roofing & Remodeling:

Removing A Metal Chimney Flue Vent

Unused Metal Vents That Penetrate The Roof Can Be Removed To Reduce Leaks

 
In This Article:

An old metal chimney vent is pried up and the fasteners are removed. Shingles are lifted carefully as needed to reach the edges of the metal flashing.

Related Articles:
Skill Level:
2-3 (Basic + )
Time Taken:
About 30 Minutes
Author:
Project Date:
November 1999
 
 
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When remodeling a house, sometimes a chimney needs to be removed. These days many people are installing high-efficiency furnaces which use PVC pipe for the exhaust, instead of a metal chimney. Since these furnaces are often vented through the side wall of the house, it may render the old metal chimney flue unnecessary.

If a metal chimney needed to be removed, it's a fairly straight-forward job. Patching the old hole in the roof is fairly easy too... if you can find shingles to match the area around the hole.

[See Tools and Materials] [Add your comments below the article]

 

Existing Vents:
Unused metal chimney flues.

This roof had two vents that were unused. A previous owner had used them as dryer vents, and they leaked during heavy rains.

As far as I could tell, these were actually 4-inch B-vent chimney flue pipes.

If you know anything about roofing, you can see why these leaked: they were installed OVER the shingles on the sides. Only the bottom edge should go over the shingles.

 

 

Removing Metal Vent Flashing:

 

I scraped the roofing tar from the deck screws that held the vents to the roof.

Then I used a cordless drill to remove the deck screws.

Removing tar from screw heads in chimney flashing.
 

 

Prying up the shingles around the chimney flashing.

I used a flat pry bar to scrape away the roofing tar that once sealed the vent to the roof shingles.

 

 

Then I peeled up the shingles to expose all edges of the vent.

This is the top edge of the metal vent flashing.

Lifting up shingles around the metal chimney flashing to expose the edges.
 

 

Prying up the old metal chimney flashing from the roof.

I pried the metal flange up...

 

 

... from all sides. It came off without a fight.

Prying up the metal chimney.
 

 

Note that the photos above are a great example of how NOT to install a roof flange. The top of the flange is barely covered by shingles. It's clear to me that whoever installed these vents could not be bothered to removed a few shingles and cover the flange properly. Read this article for more info. 

 

Lifting an old metal chimney from the roof.

The vent lifted straight up.

 

 

At this point I realized that this device was actually a chimney "B-vent", for a furnace or gas water heater. You can tell because B-vent pipe has a double wall.

It was never intended to be used for venting a clothes dryer... though it may work okay for that purpose.

View into lower end of vent pipe.
 

 

 
 
 
 
 
 
 
 

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Roof with two 4-inch holes from old vents.

The roof, after both vents were removed.

These holes are easy to fill in. 

 

 

Check Down Below:

Just out of curiosity, I wanted to see what was down that hole. Nothing but some unused pieces of vent pipe insulation.

It's a good idea to look into the attic to make sure everything is okay... of course, you wouldn't be removing an old vent flashing unless you already knew the situation.  

Interesting things found in attic.
 

 

Next Step: Patching The Holes In The Roof.

 

More Info:
Tools Used:
  • Flat Pry Bar
  • Cordless Drill-Driver
Materials Used:
  • None
 
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