How often should you water your foundation?

Short answer

Water the foundation daily or every other day in hot, dry weather. This only applies to a house on clay soil, the kind that cracks into plates in a drought, and the idea is to keep the soil around the foundation evenly damp so it doesn't shrink away from the slab. A soaker hose on a timer does it for you once it's set up, which takes 10 to 20 minutes and $20 to $60 in hoses and a timer. If your soil stays moist on its own, skip this job entirely.

Why it matters

Clay soil swells when it's wet and shrinks when it's dry, and it does both with real force. A house on clay rides on that soil, and in a long dry spell the soil around the edge of the foundation dries out first and pulls away from it. The edge of the slab, or the footing under a crawl space, loses its support and drops a little. The middle of the house, still on damp soil, doesn't. The result is a foundation that's bending, and the house shows it with cracks in the drywall, doors that won't close, and tile that pops.

When the rains come, the soil swells back and the foundation lifts, and the cycle wears on the house every year. Watering keeps the soil at the edge of the foundation from drying out, so it doesn't shrink, so the foundation doesn't drop. It's the cheapest foundation repair there is, because it's the one that stops the damage before it happens.

When to do it more often

The index gives one modifier, and it removes the job rather than adding to it: soil that stays moist doesn't need watering. This is a clay soil job, common in parts of the South and the plains, and pointless on sand, loam or anywhere the ground stays damp through summer.

Where it does apply, the weather sets the pace. Daily in a hot, dry stretch with no rain. Every other day when it's merely warm. Not at all for a few days after a good rain. The goal is steady moisture, not a swamp, and a gap opening between the soil and the foundation is the sign the ground is drier than it should be.

What you need

Soaker hoses, enough to run around the whole foundation
A hose timer, so the watering happens without you

Steps at a glance

Lay the soaker hoses on the ground around the foundation, a short distance out from the wall rather than against it, so the water soaks in where the footing sits.
Connect them to the outdoor faucet through the timer.
Set the timer to run early in the morning, long enough to dampen the soil without pooling.
Check the soil a few days later: it should be damp a hand's depth down, with no gap at the foundation and no standing water.
Adjust the run time with the weather, and turn the timer off after a soaking rain.
Disconnect and drain the hoses before the first freeze.

You're done when the soil around the foundation stays damp and even through the dry season, with no gap opening at the slab.

Signs it's overdue

A gap opening between the soil and the foundation, which means the soil has shrunk.
New cracks in the drywall, especially above doors and windows.
Doors that have started to stick.
Soil pulling away from the slab in plates, with cracks in the ground.

DIY or pro

This is an easy job, and the timer makes it a job the house does for itself. The setup is a morning's work, and after that it's a glance at the soil now and then and a change to the timer when the weather shifts. There's no service to hire for it.

A foundation that's already shown the signs, with cracks that grow and doors that stick through the seasons, needs more than a hose. That's a structural engineer's call, and watering is what they'll likely tell you to do alongside whatever else is needed, since it's the one thing that addresses the cause.

FAQ

Does watering the foundation really work?

On clay soil, yes. It keeps the soil at the edge of the foundation from shrinking away in dry weather, which is what lets the foundation drop.

How far from the foundation should the soaker hose be?

A short distance out from the wall, not against it, so the water soaks down to where the footing sits rather than running down the face of the concrete.

Should I water the foundation in winter?

No. The soil doesn't dry out in cool weather, and the hoses should be drained and put away before the first freeze.

Can you overwater a foundation?

Yes. Standing water beside the foundation causes its own problems. The aim is damp soil, so run the timer long enough to soak in and no longer, and skip it after rain.