How can you tell if a chimney is load bearing?
Short answer. Most chimneys are not load bearing in the sense of holding up the roof, because code requires wood framing to be kept clear of masonry chimneys, but some older homes have joists, beams or rafters resting on or pocketed into the chimney. Check the attic, each floor and the basement or crawlspace for framing that touches or sits on the masonry, and have a structural engineer confirm before removing any part of a chimney.
Why most chimneys are not structural
Current codes require an air space between masonry chimneys and combustible framing, 2 inches for a chimney inside the house, so rafters, joists and headers are framed around the chimney rather than resting on it. In homes built that way, the chimney supports only itself.
When a chimney may carry load
- Older homes where floor joists or a beam end sit in pockets in the brickwork.
- A ridge board or rafters resting on the chimney in the attic.
- Chimneys built as part of a load-bearing masonry wall.
- Renovations where someone used the chimney as a convenient support.
How to check
- Attic: look where the chimney passes through. Framing should stop short of the brick with a gap, and headers should carry the rafters around it.
- Each floor: look for beams or joists entering the brick, often visible in unfinished closets or from below.
- Basement or crawlspace: see whether beams rest on the chimney base or its footing.
- Exterior chimneys: check whether wall framing ties into the chimney where it meets the house.
If you plan to remove it
- Have a structural engineer evaluate it before any demolition, and expect a permit.
- Partial removal, taking the chimney down below the roofline, is common and avoids touching lower framing, but the roof opening must be framed, decked, underlaid and shingled.
- Any appliance flue that uses the chimney must be rerouted first.