Protect Your Home: Everything You Need to Know About Chimney Thimbles

If you’ve ever done a major remodel of a historical home, you might have encountered some strange things; secret passageways, hidden rooms, or a walled-off staircase. One of the most common discoveries that historical homeowners often come across is a chimney thimble port; a circular hole in the wall used to house a thimble. The thimble enters the flue inside the chimney and is designed to accommodate a stovepipe. If the homeowner no longer uses the wood-burning stove, the pipe is removed, and the thimble port is covered over by drywall, wallpaper, or a pie-plate cover.

orange ceramic pie-plate | Doctor Flue

In this case, the homeowner put up a wall in front of it, concealing the pie-plate entirely. When the next homeowner came along, they decided that they wanted to use the chimney and cut a hole in the stud wall below the pie-plate, not realizing that it was there.

Thimble ports are hazardous

Unused thimble holes in chimneys are as dangerous as any breach in the chimney’s structure. Removing a previously existing stovepipe allows creosote to collect in the thimble that eventually ignites and spreads to the surrounds studs. It not only leaks dangerous flue gasses, but also allows smoke and flames into the house.

Consider a chimney liner

The proper way to close off a thimble port is with brick and mortar to create a solid and safe enclosure. It’s important that your chimney service technician checks that the area that gets closed off has a lining. If there’s no lining due to the flue, then a new one needs to be installed. Otherwise, there’s a possibility that the pie-plate will overheat.

Insist on video inspection

You can check for a poorly patched hole in the masonry repaired with aluminum pieces or bulges behind drywall or wallpaper, but the only way to know for sure is with a video scan.

Contact Doctor Flue today!

Chimney inspections by Doctor Flue offers a level of professionalism and innovation not found in all companies. We use innovative video equipment to see the interior of our chimney. Schedule your chimney inspection today! Give us a call at 800-438-3583 or send us an email at to request an appointment.

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