Of all of the effects of foundation problems, issues with the chimney are perhaps the most unexpected. A home’s foundation is one of its lowest points while the chimney rises over the roofline.

Still, if an exterior chimney is beginning to pull away from a house, foundation problems are likely to blame. The question becomes, which foundation is the problem, the home’s, the chimney’s, or both.

What is Differential Settlement and How Does It Affect Chimneys?

Differential settlement is generally considered to be when a portion of a home’s foundation settles more than the rest of it, placing the entire structure under stress. This is the cause of many foundation problems.

But how does that impact chimneys?

We’ll discuss interior chimneys later, but for now let’s focus on exterior chimneys, those built along the side of the house. Exterior chimneys are often built on their own foundations. This means there are three types of differential settlement to consider. First, where the home is experiencing differential settlement. Second, where the chimney is experiencing differential settlement. And third, where the home’s foundation and the chimney’s foundation are settling at different rates.

Depending upon the direction of the force of the differential settlement, one of two things will happen. The first is that the settlement creates a force that begins to pull the house and the chimney apart. This creates the “leaning chimney” that is often described as being a symptom of foundation problems, whether the chimney is actually leaning or just appears to be relative to the house.

The other possibility is that the forces could be acting in the opposite direction, creating a compressive force as the push the house and the chimney together. In this case, the effect might not be quite as noticeable, but it can still be significant, leading to cracks along mortar lines and possibly a bowing of the chimney under the stress from the pressure of the house.

Are Interior Chimneys Affected By Foundation Settlement?

While the most noticeable cases of chimney damage from foundation problems are generally found with exterior chimneys, interior chimneys can be affected as well.

One of the main differences is that unlike exterior chimneys, interior chimneys generally share a foundation with your home. That doesn’t mean it is immune. It just means that you are dealing with settlement from one foundation, not two.

In this case the chimney will be impacted the same way doors and windows are. Foundation problems caused by differential settlement throw the home slightly out of alignment. This can cause doors and windows to stick or cause gaps in trimwork. Similarly in chimneys it can cause cracking especially at stress points such as where it meets floors and ceilings as well as above the roofline, where vertical cracks caused by settlement are common.

Does Your Chimney Have Structural Problems? If So, Check Your Foundation

If your chimney is experiencing structural issues, a masonry contractor might be needed to repair the damage. If the underlying problem isn’t solved, however, the problem might simply recur. Instead, also consult a foundation specialist who can help determine the cause of the chimney problems. If you live within our Oklahoma service area, contact Pierman today.