Why is a driveway sinking or heaving?

Start with the direction of movement

A low panel beside a high panel can be deceptive. One may have settled, the other may have risen, or both may have changed. A garage threshold, adjoining walk and street connection provide useful references, but the assessment needs measurements rather than an impression from a photograph. The intended surface must still work across the whole entrance.

Historic photographs can help show change when they include a recognizable fixed feature. Tell us whether the bump appeared suddenly or developed gradually, whether it changes with wet and dry conditions and whether previous repairs altered the surface. Those observations inform the investigation without proving a single cause.

Settlement can have several explanations

Inadequately compacted supporting material can consolidate later under loading, allowing the pavement to settle. That later movement is different from deliberate construction compaction, which prepares material to provide suitable support before pavement is placed. Erosion and loss of contact beneath a panel can also contribute to settlement. A trench or earlier repair may also have different support from the neighboring driveway. None of these should be assumed simply because a slab is low. The scope needs to distinguish a recoverable elevation problem from pavement that is too damaged to retain.

Read how driveway base failure affects repair choices if a depression has returned after previous work. For asphalt, a low area can involve the surface, its underlying layers or both. The right repair may be localized asphalt patching with preparation below the visible defect, rather than adding material until the surface looks level.

Heaving requires a different question

A slab can rise where underlying soil expands or an obstruction affects it. Nearby roots may deserve assessment, but their presence alone does not establish responsibility. Cutting roots or trying to force a panel down without understanding the situation can create another problem. Our tree-root damage guide explains the limits of visual identification.

Harris County Flood Control identifies clay soils in its regional explanation. That context makes ground conditions relevant, but does not prove that every parcel has the same soil or that every uneven panel is soil heave. An assessment should preserve that uncertainty. A repair chosen around a guessed cause is difficult to evaluate when the surface moves again.

Lifting must have a workable target

For suitable concrete, driveway leveling may restore a settled section toward a defined elevation. The important word is suitable. Fragmented concrete, incompatible fixed heights or continuing external pressure may rule out a straightforward lift. Raising a lower neighbor to match a heaved slab can leave the entrance higher than it should be.

Before agreeing to lift, ask how the finished surface relates to the garage threshold and the path for runoff. A smooth transition that directs water toward a building is not a satisfactory result. The pooling-water guide helps distinguish a pavement depression from a broader outlet or grading problem.

Replacement changes what can be accessed

When a panel cannot reasonably be retained, panel replacement allows the underlying area to be exposed and prepared. The proposal should describe the intended panel boundary and how reinforcement or connections to retained concrete will be addressed. It should also identify what remains outside that boundary.

Replacement is not automatically a cure for ongoing ground movement. The work below the panel, the surrounding grades and any obstruction still need appropriate treatment. Compare leveling with replacement on that basis instead of treating the two methods as interchangeable ways to remove a bump.

Plan access while the problem is assessed

Avoid using a visibly unstable or badly broken area as a test track. You can describe what you have already noticed without driving back and forth to demonstrate movement. Tell us about vehicle clearance concerns and pedestrian trip points so access arrangements can be considered while the scope is developed.

A written estimate should identify the intended finished relationship between sections, the limits of the work and the return-to-use instructions. If an approach crosses a sidewalk or public right-of-way, the relevant authority depends on the address and road. Review driveway permit considerations before assuming that changing the entrance height is only a private paving decision.

Related decisions

• What does driveway base failure mean, and how is it repaired?
• Are tree roots causing your driveway damage?
• What should you do about water pooling on a driveway?
• Should you level a driveway slab or replace the panel?