Drainage and grading cost
Regrading around a house costs $500 to $3,000 and drainage $1,500 to $8,000. Together they are the cheapest structural insurance a house has, because most foundation problems begin as water against a wall.
National average
$1,500
per project
Regrading around a house costs $500 to $3,000, typically around $1,500. Adding a drainage system costs $1,500 to $8,000. Together they are the cheapest structural insurance a house has, because most foundation and basement problems begin as water sitting against a wall.
The soil around a house settles over decades. What was a slope away from the foundation when it was built is frequently level or reversed by year thirty.
What it costs
| Job | Typical cost |
|---|---|
| Downspout extension | $10 to $100 each |
| Buried downspout line to daylight | $300 to $1,200 each |
| Regrading one elevation | $500 to $1,500 |
| Regrading around a whole house | $1,500 to $4,000 |
| Topsoil delivered, per cubic yard | $25 to $60 |
| French drain in the yard, per linear foot | $10 to $35 |
| French drain at the foundation, per linear foot | $30 to $90 |
| Curtain drain uphill of the house | $1,500 to $6,000 |
| Channel drain across a driveway | $500 to $2,500 |
| Catch basin | $300 to $1,200 |
| Dry well | $1,500 to $5,000 |
| Swale, shaped and planted | $1,000 to $4,000 |
| Sump discharge extension and freeze fitting | $200 to $800 |
| Rain garden | $1,500 to $6,000 |
| Retaining wall to hold a new grade | $20 to $55 per sq ft |
The numbers that matter
Six inches of fall in the first ten feet away from the foundation. That is the figure, and it is what most codes require for new construction.
Six inches of foundation exposed above the finished grade, so siding and framing are not in contact with soil.
Two inches above a paved surface where a patio or path meets the wall.
Downspouts discharging six to ten feet away, minimum, and further on clay soil.
Take a level and a straight board along each wall and check. Most houses over thirty years old fail at least one of these somewhere.
The cheap fixes first
In order of value per dollar:
1. Downspout extensions. Ten dollars each, twenty minutes, and they move thousands of gallons a year. Nothing else on this page comes close on value.
2. Cleaning and repairing the gutters. An overflowing gutter waters the whole wall.
3. Moving the mulch back. Mulch and soil piled against siding holds moisture against the wall and often buries the weep screed or the siding's lower edge.
4. Regrading. Adding soil to build a slope away from the house, keeping six inches of foundation exposed.
5. A swale, a shallow shaped channel that carries surface water around the house rather than through it. It is landscaping rather than plumbing and it is invisible when planted.
Only after those does buried pipe become the answer.
French drains, honestly
A French drain is perforated pipe in a gravel trench wrapped in filter fabric, which collects water in the soil and carries it away.
Two things decide whether it works, and both are invisible once the trench is filled:
Slope. It must fall continuously toward the outlet. A drain with a flat section holds water and silts up.
An outlet. The water must have somewhere to go: daylight on a lower part of the site, a dry well, or a storm connection where permitted. A French drain with no outlet is a trench that fills up.
Ask where the water leaves, and then go and look at that point. That single question separates a drain that works from one that does not.
Fabric matters. Sock-wrapped pipe in unwrapped gravel silts up in a few years. Fabric should line the trench, not just the pipe.
Frequently asked questions
Can I regrade myself?
Adding topsoil and shaping a slope is achievable with a wheelbarrow and a rake for one elevation. Do not raise the grade above the top of the foundation, and do not bury siding or a weep screed. Machine work and drainage pipe are contractor territory.
What soil should I use for regrading?
Clay-rich fill against the foundation, which sheds water, topped with topsoil for planting. Sandy or loose topsoil against the wall lets water straight down to the footing.
Where can I discharge the water?
Onto your own property, away from the house, and not onto a neighbour's land. Many jurisdictions prohibit connecting to a sanitary sewer and some prohibit storm connections too. Check locally before trenching.
Will this fix my wet basement?
Frequently, and it is what should be tried before any interior system. Surface water handled properly resolves a large share of wet basements at a fraction of the cost.
What about the neighbour's water running onto my land?
Water law varies substantially by state. A curtain drain uphill of the house at $1,500 to $6,000 intercepts it without a dispute, which is usually faster than resolving one.
Read next
Wet basement repair cost$2,000 to $15,000per projectFixing a wet basement costs $2,000 to $15,000. The cheapest fixes are outside and cost a few hundred dollars. Doing them in the wrong order is the most expensive mistake in this subject.
French drain cost$10 to $90per linear ftA French drain costs $10 to $90 per linear foot depending on depth and placement. Slope and an outlet decide whether it works, and both are invisible once the trench is filled.
Basement waterproofing cost$3,000 to $10,000per projectBasement waterproofing costs $3,000 to $10,000, averaging $5,000. Interior drain tile is $50 to $120 per foot and exterior excavation $100 to $220. Do the cheap things first.
Foundation inspection cost$300 to $1,000per eachA foundation inspection costs $300 to $1,000 from an independent inspector. Repair companies offer them free, and that is a sales visit that may also be a competent inspection.
How long does a foundation last$5,000 to $30,000per projectA poured concrete foundation lasts 80 to 100 years or more. Foundations essentially do not wear out; what fails is everything that manages water around them.