Why is my chimney pulling away from the house or leaning?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: An exterior masonry chimney is a tall, heavy column, usually on its own footing at the edge of the house. When that footing settles, or the soil under it is soft or drying, the chimney can lean away and open a gap at the wall or roofline. Earthquake shaking is another possible cause in Oklahoma, which has had several moderate earthquakes ².

Why do chimneys move differently from the house?

Most of a house is light wood framing spread along long foundation beams. A brick or stone chimney concentrates a great deal of weight on a small footing. That difference means the chimney can settle or tilt on its own even when the rest of the foundation is moving only a little. When it does, the gap typically shows at the side wall, at the roof flashing, or as cracks in the chimney itself.

What the code requires under a masonry chimney

The residential code calls for footings under masonry fireplaces and their chimneys to be concrete or solid masonry at least 12 inches thick, extending at least 6 inches beyond the face of the fireplace ⁷. The footing must bear on natural, undisturbed soil or engineered fill below frost depth, or at least 12 inches below finished grade where the ground does not freeze ⁷. In higher seismic design categories (D0 to D2), the code also requires masonry chimneys to be reinforced with vertical steel bars and anchored to the floor, ceiling or roof framing ⁷. Outside those categories, these reinforcing and anchorage rules do not apply ⁷.

What can make a chimney separate or lean?

Heavier loads compress soil more

Engineers test how much a soil compresses by loading a confined sample in increasing steps and measuring the settlement at each step ⁴. In eastern Oklahoma, for example, the Osage floodplain soil is a poorly drained clay with a seasonal high water table 6 to 18 inches below the surface from November through May ⁵. A chimney footing on soil like that carries its load into ground that stays soft for much of the year.

Drying clay at the perimeter

A chimney stands at the outside edge of the house, where soil dries the most in summer. Expansive clay shrinks as it dries, and dry-season cracks in such soil can be about an inch wide at the surface ⁶. See shrink-swell and the active zone.

Earthquakes in Oklahoma

Oklahoma's earthquake activity rose sharply after 2009: about two magnitude 3.0+ events per year before then, compared with 903 in 2015 ². Notable events include the magnitude 5.7 Prague earthquake (2011), the magnitude 5.8 Pawnee earthquake (2016) and the magnitude 5.0 Cushing earthquake (2016) ². Historically mapped seismic areas include El Reno-Mustang, central Oklahoma, Love and Carter counties and the Arkoma Basin ³. After the 2016 Pawnee earthquake, a Pawnee resident was injured by bricks falling from his chimney ⁸. A chimney that cracked or separated right after a felt earthquake, with fresh crack faces, points toward shaking; see seismic damage vs soil movement.

How should it be documented?

1. Measure how far the chimney is out of plumb over a known height with a level or plumb line.
2. Measure the gap between chimney and wall at the bottom, middle and top.
3. Photograph cracks in the chimney with a scale, and note whether crack edges are clean or weathered.
4. Note when the gap was first seen, and whether it followed a dry summer, a wet season or an earthquake.
5. Include the chimney on a whole-house elevation survey.

Home inspection standards include inspecting the chimney from ground level or the eaves and reporting signs of possible foundation movement, such as brick cracks ¹.

What are the next steps?

Compare the pattern with the distress pattern library and the symptom matrix. For a chimney that continues to move, see working with engineers.

Related

• Concentrated load settlement
• Earthquake shaking damage
• Induced seismicity in Oklahoma
• Fresh, clean-edged cracks appearing suddenly
• Steel push piers