Drought watering and a foundation on clay

A long dry spell hits a house in two places. The lawn and beds need water, and the soil around the foundation dries out. On clay, the second one matters as much as the first.

Why clay soil matters to a foundation

Expansive soils swell when they get wet, and they can press on a foundation hard enough to crack it or lift it. Collapsible soils shrink when they get wet, and the ground sinks. Either kind can leave a trough along the wall that collects water and sends it toward the foundation. Whether your lot is on expansive or collapsible soil takes a hydrologist, a soil scientist or an engineer to say.

Watering in a drought

Your local water utility or the cooperative extension service can tell you how often to water where you live. The water goes further when you:

• Water early in the morning or in the evening. In the middle of the day, the sun evaporates much of it before it gets to the roots.
• Split each watering on clay or a slope into shorter runs with breaks between them, so the water soaks in instead of pooling. This is called cycle and soak.
• Measure what the sprinkler puts down. Set a few empty tuna cans on the lawn and time how long it takes to fill them with half an inch of water.
• Stop when water starts to pool.
• Put a rain barrel under a downspout to catch what rain does fall.

Let the lawn go

Most landscapes need about an inch of water a week, rain included. In a long drought, the lawn is the easiest place to cut back. Cool-season grasses can go dormant in hot, dry weather and recover when it turns cooler and wetter, and warm-season grasses handle heat better.

Watering along the foundation

A soaker hose laid in the bed between the foundation and the base of the shrubs puts water where the house needs it, and it helps keep the foundation from cracking. Use one with enough pressure to squirt water at least 3 inches high from its openings. Skip the kind that sweats along its length, since those clog and water unevenly.

Spread 2 inches of mulch over the hose and around the shrubs, and add more at least twice a year. Run the hose at least 4 hours a day, every 2 weeks, in place of an inch of rain.

An annotated example

What to do next

Ask your water utility or extension service how often to water in a drought. Lay a soaker hose in the beds between the foundation and the shrubs, under mulch. Make sure the downspouts still carry water 5 feet or more from the house, so the first storm doesn't dump it all at the foundation. Fixing water that pools in the yard covers the downspouts and the grade.