Soil pulling away from the foundation
A gap along the wall is an open channel for rain. It usually comes from drying clay, settled backfill or both.
When soil pulls away from the foundation, it leaves a gap that lets rain and roof water run straight down along the wall. The gap itself is rarely the cause of a problem. It is a warning that the ground beside the house is shrinking or settling, and it also makes every storm worse.
This page prints no prices. It explains the causes and the safe steps, and it stops where a structural question begins.
Why the soil shrinks away
Clay soil swells when wet and shrinks when dry. In a long dry spell, the ground near the wall can contract and split away from the concrete. The gap often appears on the sunny side first, where the soil dries fastest.
Backfill is the second common cause. Soil placed against a new foundation settles for years as it compacts. That settling leaves a trench-like dip beside the wall.
What the gap does
- Rain and downspout water drop into it and reach the lower wall.
- Water finds the footing faster than it would through solid soil.
- The dip holds water against the wall instead of shedding it.
In a dry spell the gap is a nuisance. The first heavy rain afterward is when it matters.
What you can safely do
Keep the area from making things worse. Rebuild the slope with compacted soil so the ground falls away from the wall, and keep the fill below any siding. The grading and downspouts page shows what that slope should look like.
Then check every downspout. Roof water landing near the gap is the fastest way to turn a crack in the soil into a wet basement. Extensions are covered in downspout drain pipe.
Do not just fill it with loose soil
Loose topsoil poured into a gap washes straight back out, or compresses and leaves the dip again. Pack the soil in layers. Skip a bag of gravel as the whole fix, because gravel against a wall can carry water down faster.
Watering the soil near the wall during very dry weather can slow the shrinking in clay. Do it lightly and do not soak the ground, which defeats the point.
When the gap points to something bigger
A gap that returns every summer is normal in clay. A gap that keeps widening, with new cracks in the wall or sticking doors upstairs, is a different story. The soil may be moving because the foundation is. Read when to worry about foundation cracks. Take a position: a gap alone is a drainage chore, but a gap plus wall movement is not.
Where to stop and call someone
If a wall is cracked, bowed or leaning, do not dig beside it. Excavating next to a stressed foundation can make it worse. That call belongs to a licensed structural engineer, and an independent one has no repair to sell you. For local grading rules, ask your building department.
Frequently asked questions
Why is soil pulling away from my foundation?
Usually drying clay shrinking in dry weather, or backfill that is still settling. Both leave a gap along the wall.
Is a gap between soil and foundation serious?
On its own, it is a drainage issue. A gap that widens, or comes with new wall cracks, deserves a look from a licensed structural engineer.
How do I fix soil pulling away from the foundation?
Pack compacted soil in layers, rebuild a slope that falls away from the wall and send downspouts well clear.
Does a gap let water into the basement?
It can. Rain runs down the gap along the wall and reaches the footing faster than it would through solid soil.
Should I dig beside the foundation to fix it?
Not if the wall is cracked or leaning. Digging next to a stressed foundation can make it worse, so ask a licensed structural engineer first.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- US EPA. What You Can Do to Soak Up the Rain
- US EPA. Soak Up the Rain. Managing stormwater around a property