Old brick chimney needs sweeping change

Hey there, time traveller!
This article was published 15/10/2016 (3277 days ago), so information in it may no longer be current.

QUESTION: I have a house in the country that’s about 75 years old with a brick chimney above the roof and square cinder blocks below the roof. The house used to be heated by a wood furnace, but about 30 years ago was converted to forced-air electric heat. There is no fireplace. I am hiring a roofer to reshingle the roof and was wondering what the pros and cons are of removing the chimney? What would you do?

Thank you very much for your anticipated reply, Harold Billan

Answer: Some home renovations or modifications can be done any time, without significantly impacting other systems or areas of the home. Others, like your chimney removal, can wait until the situation is more opportune, such as when the roofing is being replaced. That will be an ideal situation, as the shingle upgrades will allow better patching and sealing of the roof sheathing and roofing, preventing possible leakage.

Most systems in our homes require periodic maintenance or repair. Items that are subject to outdoor environmental conditions especially need some TLC to prevent excessive damage. Older brick chimneys fall into this category, as the brick is porous and the mortar is subject to deterioration over time. Regular inspection of the chimney for damaged bricks or crumbling mortar will tell if repairs are required. Also, metal flashings near the top and bottom of the chimney’s exterior above the roofline often corrode or come loose and need to be secured or replaced. While these repairs may only be required every decade or so, it’s rather wasteful to put resources toward an older, redundant chimney, just to keep it from falling apart.

The main reason to remove the chimney is to eliminate the need for repairs when the chimney does begin to erode. There is no sense spending money or time fixing something that’s no longer required. It also may not be prudent to knock down the old stack when the roof is in good condition, as this will necessitate a roof patch and repair and risk damage to the existing roofing. It can be difficult to match the older shingles, as well as properly patch the hole where the chimney is, without removing a larger section of roofing. That’s why the chimney’s removal is ideally suited to a time when the shingles are also being replaced.

Knocking the old bricks apart often isn’t much more difficult than climbing the roof, ensuring proper harnesses and other safety measures are used, and dismantling the chimney with a sledge hammer. Care must be taken to protect the area below, and prevent any pedestrian traffic, due to flying debris. The eavestroughs and roofing surrounding the chimney should also be protected, possibly with old plywood or other sheathing, to prevent damage from dropping bricks. Once the part of the chimney that exists above the roof is taken down, another decision has to be made before continuing.

Deciding how much of the chimney to remove may depend on how much work you want to take on, or to budget for the job. If you decide to remove it just below the roofline, that may only require sealing the top and insulating it to prevent warm air intrusion into the attic. If you decide to remove all of the chimney inside the attic, you may need to do some minor structural repairs to the rafters if they’re being partially supported by the old brick. Otherwise, removing the bricks inside the attic will require further protection of the attic floor, to prevent damaging the ceiling finishes in the home.

If you decide to stop at the attic floor, insulating inside and around the top of the chimney and air sealing it should finish the job. If you decide to remove the chimney all the way to the bottom, patching and air sealing the ceilings and floor inside the home will also be required.

So far I’ve listed only the benefits of chimney removal, but you also inquired about any negative aspects.

The only possible negatives of removing your chimney when you upgrade your shingles are the same as with any other renovation. If things are done properly, there should only be benefits, but if corners are cut or improper repairs done there could be moisture issues afterwards. The possible screw-ups include improper roof patching and reinforcement of the rafters or trusses, if needed. This is less likely than the more common omission of air sealing either the top of the chimney inside the attic, or the ceiling itself, if the stack is removed further down.

It’s doubtful that a professional roofing contractor would not properly patch the roof sheathing after your chimney is gone, but much more likely that the inside air sealing is missed. If that is omitted, condensation and moisture issues inside the attic are almost guaranteed. Further sealing the bottom of the flues and cleanouts in the basement will also help prevent this type of damaging warm air intrusion.

The benefits of removing your old, unused chimney above the roof when the shingles are replaced far outweigh the potential negatives, unless the job is amateurishly done. If the few important items mentioned are taken into consideration, and properly attended to, you should have better protection from leakage at the roof as well as less maintenance in the future.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the former president of the Canadian Association of Home & Property Inspectors — Manitoba. Ari can be reached at 204-291-5358, or check out his website at trainedeye.ca. Questions can be emailed to trainedeye@iname.com