Watching a slab through a dry summer

Soil moves. Clay-bearing soils swell when they are wet and shrink when they dry, and a slab sitting on them moves a little too. A dry mid-South summer, especially one with watering restrictions, can pull enough moisture out of the ground for that movement to become visible indoors.

What is usually normal: fine hairline cracks in a slab or in drywall, particularly in the first year or two of a new build as everything settles and dries. Doors that stick in humid weather and free up again when it dries.

What is worth attention:

• A crack you can fit a coin into, or one that is visibly wider at one end than the other.
• Cracks that are still growing — mark each end with a pencil and date it, then look again in a month. That simple habit answers the only question that matters, which is whether it is moving.
• Stair-step cracking through brick mortar joints.
• Doors or windows that have gone out of square and stayed that way through a change of season.
• Gaps opening where a wall meets the ceiling or the floor.

The most useful thing you can do in a drought is keep the moisture around the foundation even. Soaker hoses a foot or two out from the slab, run briefly and regularly, do more good than an occasional soaking. The goal is consistency rather than volume — it is the swing between wet and dry that moves a foundation, not moisture itself.

Keep water away in the other direction too. Everything in the gutters and drainage article applies here; the two problems are the same problem viewed from different seasons.

Call someone if: a crack is growing, you see stair-step cracking in brickwork, floors have begun to slope, or doors and windows have gone out of square and stayed there.