The cause
Drainage and grading around a foundation
Soil moves because water does. Fixing where water goes is the cheapest real foundation repair, and the code’s baseline.
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Written by HyreFoundation Research Desk Primary-source research and fact checking
The short answer
Good foundation drainage means the ground falls at least 6 inches within the first 10 feet from the wall (about 5%), paving within 10 feet slopes at least 2% away, and roof water discharges well clear of the house.
That is the International Residential Code baseline under R401.3. It is the cheapest fix for soil movement, and it belongs before any structural repair.
Key takeaways
The code switches between them based on a finding about your site, not on how much you spend.
Both drying and wetting move a house.
What to check yourself, this weekend, for nothing
In rough order of how often it turns out to be the answer.
A downspout emptying at the wall delivers the entire roof plane to one spot of soil. Extensions that carry it well clear of the foundation are the single highest-value few dollars in this whole field.
Overflowing gutters are a downspout problem wearing a disguise.
Stand at the wall and look. Soil settles over the years and beds get topped up, and a house that was graded correctly in 1998 frequently is not now.
A patio or driveway pitched the wrong way delivers water to the wall faster than soil ever could, and it is the case the 2 percent rule exists for.
Sprinkler heads throwing at the foundation, or a drip line in a bed against the wall, keep one strip of soil permanently wet while the rest of the perimeter cycles. Differential moisture is what does the damage, not moisture.
Also check that soil is not piled above the damp-proofing or against siding.
A regraded lot or a new patio next door can redirect a surprising volume.
A new deck, a removed tree, a replaced driveway, a repaired main. Foundations respond to changes in water, and changes in water are usually human.
The order to do this in
Cheapest and most reversible first. It is also, conveniently, most-likely-to-work first.
Clear gutters, then extend downspouts. This is the intervention with the best ratio of cost to effect in the entire subject and it can usually be done in an afternoon.
Re-establish fall away from the wall — around six inches over the first ten feet. Where a lot line or a slope prevents it, the code’s own answer is a swale or a drain rather than accepting the fall toward the house.
Slabs pitched toward the house can sometimes be lifted and re-pitched rather than replaced. This is one of the legitimate uses of slab lifting.
Free, immediate, and reversible. If symptoms respond over a season, that is diagnostic information you did not have before.
Begin an elevation log and dated crack photographs at the same time you make these changes, so you can tell whether they worked. Without a baseline, "it seems better" is not a finding.
Exterior excavation and waterproofing, or an interior drain tile and sump, are real solutions to real problems and they cost orders of magnitude more. They also do nothing that the four steps above have not already been given a chance to do.
What the residential code asks for
The base International Residential Code provisions on grading, drainage and below-grade walls are set out below. Your jurisdiction adopts and frequently amends them, so the local building department is the authority — but this is the shape of it.
| Option | What it means for you |
|---|---|
| R401.3 — surface drainage | Lots graded to drain surface water away from foundation walls, with the grade falling not fewer than 6 inches within the first 10 feet. Where lot lines, walls or slopes make that impossible, drains or swales shall be constructed instead. Impervious surfaces within 10 feet slope not less than 2 percent away. |
| R405.1 — foundation drainage | Drains required around concrete or masonry foundations that retain earth around usable space below grade. Gravel drains extend at least 1 foot beyond the footing edge and 6 inches above its top, under a filter membrane. Exception: not required on well-drained ground or sand-gravel soils (Unified Soil Classification Group I). |
| R406.1 — damp-proofing | The baseline for below-grade walls enclosing interior space: damp-proofed from finished grade to the higher of the top of the footing or 6 inches below the top of the basement floor. On masonry, not less than 3/8-inch Portland cement parging before the coating, unless a material is approved for direct application. |
| R406.2 — waterproofing | Replaces damp-proofing "in areas where a high water table or other severe soil-water conditions are known to exist". Named materials include two-ply hot-mopped felts, 6-mil polyethylene or PVC, 40-mil polymer-modified asphalt, 60-mil flexible polymer cement and 60-mil liquid-applied synthetic rubber. |
| R408.6 — crawl space grade | Rarely quoted: where there is evidence groundwater can rise to within 6 inches of the finished floor at the building perimeter, or that surface water does not readily drain from the site, the under-floor grade must be brought as high as the outside finished grade unless an approved drainage system is provided. |
Code text above was read through code mirrors rather than the publisher’s own server, which blocks automated retrieval, and states amend Chapter 4 materially. Treat these as the shape of the requirement and confirm the adopted local text before relying on a number in a dispute.
Damp-proofing is not cheap waterproofing.
In the code, damp-proofing is the baseline and resists moisture and vapor. Waterproofing replaces it where the site has a high water table or severe soil-water conditions, and it resists liquid water.
Get in writing which one you are buying and why. The code does not say "hydrostatic pressure" here, so a quote citing that as code text is paraphrasing.
What to ask before you sign
The full checklist is on choosing a foundation contractor.
Where this goes wrong
In expansive clay, soil that dries out shrinks and soil that wets swells. Watering one side of a house through a drought while the other bakes creates exactly the differential the house cannot tolerate. The target is even moisture, not minimal moisture.
A perimeter drain and sump manages water entering a basement. It does not address structural movement, and it is frequently sold in the same visit by the same company, which is where the confusion comes from.
The words are used interchangeably in advertising and are not interchangeable in the code. Get the specification, not the adjective.
Grade has to fall away, but not by burying the damp-proofing, the weep holes or the bottom of the siding. Correcting one code problem by creating another is common.
A drain placed against a guess intercepts nothing. Establish the source and the path before trenching.
If four things change simultaneously and the symptoms improve, you have learned nothing about which one mattered — and you will not know what to maintain.
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Tell us about the work
Three short steps: the job, your home, and how to reach you. Nothing goes to a foundation company unless you agree.
A straight answer first. Matching is still being built, so this is not an instant quote. If a wall is moving or a door frame has racked out of square this week, call a structural engineer first.
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Questions
How much slope do I need away from my house?
Do I need a French drain?
Will fixing drainage repair foundation damage that already happened?
Should I water my foundation during a drought?
Is a sump pump a foundation repair?
Is a wet crawl space a code issue?
Written and audited by
HyreFoundation Research Desk
Primary-source research and fact checking
We read the model building code, the federal soil and moisture guidance and the insurer position ourselves, and we publish each figure with the document it came from and the date we retrieved it.
Where a number cannot be traced to a primary source, we say so instead of printing it. HyreFoundation does not inspect, engineer or repair foundations. Authorship is organizational: this desk, not a named persona.
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How this desk works
- Primary sources only. Code statements come from the International Residential Code, Chapter 4, as the model code. Soil statements come from USDA and USGS. Insurance statements come from the policy language and the Insurance Information Institute. We open the source rather than cite a blog that cites it.
- The code is a model, and adoption is local. Your jurisdiction adopts an edition and amends it, and foundation chapters are amended more than most because frost depth and soil are local facts. Every code figure says so.
- We hold no job data. We have no dataset of bids, pier counts or invoices, so no page claims an average from one. Calculators show the arithmetic and the inputs they assumed, and label the result as an estimate.
- We do not diagnose your house. A crack guide can tell you which pattern to measure and when to call a structural engineer. It cannot tell you whether your foundation is failing. An engineer on site does that work.
- We do not repair foundations, and we take no payment for placement, ranking or a favorable mention. Nobody buys a position on this site.
Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
Information on this page is general and varies with soil, climate, foundation type, building code, insurance policy and circumstance.
It is not engineering, insurance or legal advice, and no page can tell you whether your house has a structural problem: that needs a licensed professional on site.
HyreFoundation is an independent foundation resource, not a repair contractor or an engineering firm, and does not perform, supervise or warrant foundation work.