|Stone chimney before|
We are seeing a lot of leaning chimneys these days. This project is on a 100-year old home Kansas City, Missouri, that required tear down and rebuilding of the stone chimney. We poured a new foundation, rebuilt a frame wall on the house to bring it back into plumb, and are currently rebuilding the the chimney using stone at the base, and a stone/brick combination further up. The chimney had moved 14”out of plumb, was bowed out in the center, and was in severe danger of collapsing. The homeowners were concerned that it was a safety hazard, and indeed it was.
|Chimney 14" out of plumb|
Watch out for the hidden leaning chimney – one that has trim work on the exterior added to conceal a space between the chimney and the house. We've seen some trim added that was 1” wide at the bottom and 6” wide at the top. Signs of chimney movement can also be found at the flashing area, where you may find flashing pulled out of place or large gaps. The homeowner may also complain of a leak.
|Tony Gross and Ricky Cline on the job|
Anytime a chimney is moved it is likely to have interior damages that can be a fire hazard, so it is imperative for the homeowner to call a qualified chimney sweep to inspect the interior using an interior camera system. If cracks in flue tiles or shifted flue tiles are found, relining will be necessary. When a chimney pulls away from the house, a gap is usually left behind the facial wall of the fireplace, which is not a structural part of the chimney. This space can allow heat to escape into an area where there are likely combustible framing and headers, so a gap here can be a real fire hazard. It is common for masonry chimneys to shift or settle slightly, so this is an area that needs to be inspected at the time of any chimney evaluation and if gaps of any size are found they should be packed in with mortar.
We've also seen some rare instances where a chimney leans in towards a house, and that presents a more difficult problem because access to the foundation is not as easy. The solution is usually to tear the chimney down and rebuild it.
When a chimney starts to show structural failure with cracks in the masonry or bowing of the masonry, or if the structure has shifted far out of plumb, the chimney needs to be taken down completely and rebuilt. Homeowners should consult with a chimney construction specialist or structural engineer if they are in doubt about what to do, since there is a “gray area” where the solution could be either piering or rebuilding, and is a matter of opinion.
Homeowners can help prevent chimneys from leaning by thoroughly watering the foundation every two or three days during drought in order to keep clay and dirt packed against the foundation.
|Prep work involved bracing the chimney so it |
didn't collapse during the tear-down process
For the safety of our crew (and to protect the neighbor's house), Gene set up special supports using the neighbor's stone porch as a counter support during the tear down process. The supports were constructed using $250 worth of 4” x 6” x 16' lumber (see photo). This is usually not required, but it is a useful technique to know. The lumber can be reused. The crew set up roof protection and scaffold with safety rails and walk-boards installed, and removed all of the stones from the chimney one at a time from the top down. This is the only way to safely tear down a chimney. A commercial dumpster was placed on site for debris removal, however, most of the stones were still in good condition so they were saved and reused.
|Ricky Cline pointing in the new stones|