Problems
Poor drainage around concrete
Water sits where it should not, or runs somewhere it should not.
Water is behind a large share of residential concrete problems. It moves the soil that supports slabs, gets into concrete and freezes, and collects in cracks and opens them. Almost every settled slab has a water story somewhere in it. That is most visible on a patio, where settlement and fall are the same question asked twice.
This is the least glamorous page on this site and probably the most useful one. What a contractor actually does about it — regrading, extending downspouts, cutting in a swale — is covered in drainage correction around concrete.
What to check yourself
Go outside during or just after heavy rain and watch. Not afterwards — during. Where does water come off the roof, where does it land, and where does it go from there? This single exercise identifies most drainage problems on a residential property.
Then look at the specifics: downspouts discharging within a few feet of a slab, extensions that have come apart or been removed, ground that slopes back toward the house, slabs that have settled into a reverse slope, and low spots that hold water long after rain stops.
- Downspout discharge points relative to driveways, walkways and patios.
- Whether the ground falls away from the house or toward it.
- Standing water more than a day after rain.
- Water running into a joint or crack rather than across the surface.
- Soil washed out or visibly eroded at slab edges.
Why concrete work without drainage work often fails
If a driveway panel settled because water has been running under it for years, lifting the panel resets the height and leaves the water running. The same void reopens on the same timescale.
This is why a contractor asking about downspouts before quoting is a good sign. It is also why a quote that includes an extension or a regrade may be better value than a cheaper one that does not, even though it costs more on paper.
The cheap fixes are often the real fixes
Extending a downspout so it discharges well clear of a slab costs very little and addresses a genuine cause. Clearing gutters so water leaves the roof where it is meant to costs nothing. Correcting a low spot in a lawn where water collects against a patio is a morning with a shovel.
None of this is concrete work, and none of it is what a concrete contractor is there to sell. That is exactly why it is worth raising yourself.
What to photograph, and when
During rain, not after. The useful photographs are of water in motion — where it comes off the roof, where it lands, the path it takes across the ground, and where it collects or disappears. Ten minutes outside in bad weather is worth more than any amount of inspection on a dry day.
Take a second set an hour after the rain stops, and a third the following day. Water still standing twenty-four hours later is telling you something that the same spot dry on a Tuesday afternoon never will.
Keep the dates. If you end up comparing quotes, a contractor who can see what actually happens on your property in a downpour will give you a better answer than one working from a description, and it settles arguments about whether a drainage item belongs in the scope.
What to ask a contractor
- Where is water coming from that affects this concrete?
- What would you change about where water goes, before or alongside the concrete work?
- Will this work change the slope, and which way will water run afterwards?
- Is any drainage work included in this price, or is it a separate scope?
Before you ask anybody for a price
Four things worth settling first. None of them needs a contractor, and none of them needs your contact details — they are simply what separates a useful conversation about water going somewhere it should not from an expensive guess.
Cosmetic, functional or structural
We cannot tell you which of these applies to your property — nobody can from a distance. What follows is how the three differ, so you can look at your own with a clearer question in mind.
- Cosmetic covers staining, marking and growth on a surface that gets wet often. It looks poor and it tells you where water sits, which is genuinely useful, but it is not itself damage.
- Functional is water standing long after rain, running back toward a building, or crossing a surface in a way that makes it unusable or unsafe in cold weather.
- Structural is where the water is reaching ground that supports something, which is how a drainage problem quietly becomes a settlement problem.
- Drainage is the one category where the cheap intervention is usually upstream: changing what arrives is nearly always easier than moving what has already arrived.
What to record before requesting proposals
Contractors price what they can see. Arriving with these already noted is the difference between quotes you can compare and quotes you cannot.
- Where water actually goes during heavy rain, not where it should go. This means going outside while it is raining, which is why almost nobody has this information.
- Where it is still standing a few hours after the rain stops — the more informative of the two observations, and the one that is almost never made.
- Every roof discharge point within reach of the affected area, and whether anything has been extended or rerouted.
- Whether the fall of the surface is away from the building or back toward it, checked with a hose if rain is not obliging.
Keep it in the Project Brief if you would rather not lose track of it — it prints to something you can hand to whoever comes out.
Signs that justify getting somebody out sooner
These are observations, not deadlines. Nothing here is a reason to rush a decision; they are the situations where waiting has a cost worth knowing about.
- Water reaches a wall or a doorway rather than merely standing on open ground.
- A previously dry area has started staying wet, with no change in the weather to explain it.
- Standing water is freezing on a route people use.
- The wet area sits over ground that supports a structure rather than over open lawn.
What not to assume
- That a drain is the answer. A drain conveys water; it needs somewhere lower to convey it to, and on level ground that place may not exist within the boundary.
- That the problem is where the water ends up. It is more often where it arrives, in what quantity, and how often.
- That resurfacing changes drainage. It changes what the water runs across, not which way the ground falls.
- That because it only happens in heavy rain, it is not doing anything. Repetition is the mechanism; a single event rarely matters.
How we know what this page says
Each of these is something this page says. What follows is why we say it, what we had to assume, and what would change our mind — so you can weigh it rather than take it on trust. How we grade what we publish.
Water where it should not be is more often a symptom of something else than the problem itself.
Strong field consensus Most experienced people would say the same thing, though it rests more on accumulated field experience than on anything formally settled. You will find few practitioners who disagree, and some who qualify it.
Evidence considered
- Water arrives somewhere because of where it is directed and how the ground falls, both of which are upstream of the slab.
- Correcting drainage frequently resolves conditions that were being attributed to the concrete.
- Repairs carried out while water is still arriving have a poor record.
Still to establish
- Water source — partly, on your own
- Drainage — you can check this yourself
- Soil movement — partly, on your own
Why we say this, and when it may not apply
Homeowners generally report the water, and the water is generally the third thing in a chain that starts with a slope, a discharge point or a leak. Fixing the visible end of the chain does not stop it.
What we had to assume
- That the water has an identifiable source, which is usually but not always the case.
- That the source is accessible enough to be corrected.
When this may not apply
- Where the water table is genuinely high, there may be no upstream source to correct.
- Where the concrete itself has failed in a way that admits water, the slab is part of the chain.
- Where a plumbing leak is the source, this is not a concrete question at all.
What would change it
- Establishing that wetness does not track rainfall or irrigation, which points at a leak or groundwater.
- Watching where water actually goes during rain, which frequently identifies the source outright.
- Meter movement with all fixtures off.
Strong field consensus does not mean this: It does not mean the question is closed, and it does not mean a contractor who sees it differently is wrong or dishonest. Consensus is a description of what most people think, which is not the same as proof.
Where water is contributing, correcting it first tends to protect whatever slab work follows.
Strong field consensus Most experienced people would say the same thing, though it rests more on accumulated field experience than on anything formally settled. You will find few practitioners who disagree, and some who qualify it.
Evidence considered
- Water contributes to several of the mechanisms that damage and move concrete.
- A correction carried out while the contributing condition continues is exposed to it from day one.
- Drainage work is frequently cheaper than the concrete work it protects.
Still to establish
- Drainage — you can check this yourself
- Water source — partly, on your own
- Access — you can check this yourself
Why we say this, and when it may not apply
Sequencing is one of the few things a homeowner can influence directly, and getting it wrong is a common way for good work to fail early.
What we had to assume
- That water is in fact contributing, rather than being coincidental.
- That the drainage correction is within reach at reasonable cost.
When this may not apply
- Where water is not part of the mechanism, sequencing this way delays the actual work.
- Where a trip hazard or similar makes the concrete an immediate safety matter, that comes first.
- Where the drainage correction requires the concrete to be lifted anyway, the sequence is set by access.
What would change it
- Observation during rain establishing whether water actually reaches the affected area.
- Establishing that the wetness does not track rainfall, which points elsewhere.
- Finding the slab must come up regardless, which reorders the work.
Strong field consensus does not mean this: It does not mean the question is closed, and it does not mean a contractor who sees it differently is wrong or dishonest. Consensus is a description of what most people think, which is not the same as proof.
Common questions
How far should a downspout discharge from concrete?
Far enough that water is not soaking into the ground supporting the slab, which depends on your soil, slope and how much roof drains to that point. General guidance varies and specific requirements can be set locally, so rather than fixing on a number, look at where the water actually goes and whether it is finding its way under anything.
Should I fix drainage before or after the concrete?
Before, or at the same time. Fixing it afterwards means the new work spends its early life in the conditions that damaged the old work.
Work it out, or judge the quote
Related guides
Concrete settlement
The process behind sunken slabs: why ground loses volume and what makes it stop.
Read more →Voids under concrete
Space beneath a slab — often before anything has visibly dropped.
Read more →Sunken concrete
A slab that now sits lower than it should — almost always a ground problem, not a concrete problem.
Read more →Replacement and new flatwork
Removing failed concrete and pouring new — plus what separates a good pour from one that fails early.
Read more →Driveways
The heaviest-loaded flatwork most homes have, and the most expensive to get wrong.
Read more →