Alternatives to chimney rebuild

New liner, bolted supports may do the trick

By Inman News Feed
Add Comment Add Comment | Comments: 0 | Posted Nov. 4, 2010

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New liner, bolted supports may do the trick

Bill and Kevin Burnett
Inman News

Q: After a heavy rain, we discovered that our unused fireplace insert had filled up with water. It seems that our brick chimney has developed a leak. When you push against the chimney it wiggles a bit.

We got a quote on tearing part of the chimney down and rebuilding it. Is there a cheaper alternative to a brick chimney? As part of the job we will be removing the fireplace insert that was not installed correctly. Thanks for any insights you can provide.

A: We think you can save your chimney -- and a lot of dollars. We always like to take the conservative approach and would bring out the demolition tools only as a last resort. It could be that all you need is some support for the chimney and a fix for the leak.

Before you hire a demolition contractor, see if there is a cap on the chimney. The leak could simply be rainwater entering the top of the chimney and pooling in the fireplace insert. If that's the case, install a chimney cap and that problem will be solved.

That won't fix the wiggle, though. To stop the wiggle, first on the to-do list is to have the fireplace and the flue inspected by a licensed and bonded chimney sweep. These specialists can tell if the chimney lining is intact, or whether there is lining at all.

Either way, we see no reason to tear down the chimney.

If the flue liner is cracked or isn't there, a metal flue liner can be retrofitted down the chimney into the firebox. This will work quite nicely since you are planning to remove the insert anyway.

As far as the chimney itself, we're guessing that it is made of unreinforced masonry. In other words, no steel was placed in the chimney structure; it's just one brick stacked on top of another.

Over time, the mortar decays and the structure weakens. If this is the case, we have a hard time seeing how tearing down part of the chimney and rebuilding it is going to get you anywhere.

Rather, if the chimney is serviceable, we recommend that you install supports around the top of the chimney and lag-bolt them to rafters. This will not only stop the wiggle but will increase the chance that the chimney won't tumble in a quake. A structural engineer can tell you the best and safest way to go about this.

Your chimney sweep can also tell you if the mortar joints need re-pointing and if the step flashing where the chimney meets the roof needs to be replaced.

Re-pointing is called for when mortar begins to deteriorate. Mortar is scraped from the joints at about a 1/2-inch depth, any loose sand is brushed or washed away, and the joint is moistened and new mortar is forced into the joints. If the job is done properly, you get many years out of this repair.

Step flashing consists of pieces of L-shaped metal that are embedded into the brick joints and woven through the roofing material on the sloped side of the chimney where it meets the roof. Sometimes the metal rusts through or pulls out of the mortar joints. This might also be the source of your leak.

Check out these alternatives before tearing down and rebuilding. You just might save yourself a pile of cash.

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