Costs and decisions
Repair or replace concrete?
You have a problem and four possible answers, and every contractor sells a different one.
This is the question underneath almost every other question on this site. Repair, level, resurface or replace — four answers, very different costs, and a real chance of picking the wrong one because the contractor you called happens to specialise in it. Some of what prompts the question turns out to need nothing at all: surface crazing is the clearest example of a pattern that alarms and does not signify.
The useful way through it is not to compare the options against each other. It is to work out what is actually wrong, because each option assumes something different about the problem, and most of the time only one or two of those assumptions hold. Where two methods genuinely survive that test, the method-by-method comparisons set out what actually separates them.
What each option assumes
Leveling assumes the concrete is sound and only its elevation is wrong. If that is true, it is usually the least disruptive answer. If it is not, lifting produces a damaged slab at a better height.
Localized repair assumes the problem is contained and the rest is fine. That holds when the cause was local — a trench, a downspout, a root. It does not hold when the same failure is starting in four other places.
Resurfacing assumes the structure is sound and only the surface has failed. It cannot correct movement, and it will reproduce a moving crack along the same line.
Replacement assumes the concrete itself is finished. It is the only option that lets you change thickness, reinforcement, slope or layout, and the only one that resets the base.
The three observations that decide it
First: has it moved, or has it deteriorated? Movement is a ground problem and points toward leveling or replacement. Deterioration is a concrete problem and points toward resurfacing or replacement. Both together usually means replacement.
Second: is the slab still one piece? Lifting requires a slab that moves as a unit. Concrete in several pieces cannot be lifted meaningfully and cannot be usefully resurfaced.
Third: is it still changing? A stable problem can be treated on its own terms. An active one means the cause is still running, and anything installed over it inherits the countdown.
- Moved, intact, cause fixable → leveling is worth pricing.
- Deteriorated on the surface, sound underneath, unmoved → resurfacing is worth pricing.
- Contained damage, stable, rest of the area fine → localized repair is worth pricing.
- Broken up, crumbling, widespread, or several of these at once → replacement is the realistic path.
- Still actively moving → find out why before choosing any of them.
The trap of the cheapest answer
The cheapest option is only the cheapest if it holds. Lifting a slab for a fraction of replacement is excellent value when the slab is sound and the cause has finished, and poor value when it needs replacing in two years anyway.
Conversely, replacement is not automatically the safe choice. Replacing sound concrete that has simply settled means paying for demolition, disposal and a new pour to solve a problem that lifting would have solved.
The question is not which is cheaper. It is which is true.
When to get more than one opinion
When a contractor who only does one thing recommends that thing, that is not dishonest, but it is not independent either. A leveling specialist looking at a marginal slab and a replacement contractor looking at the same slab will often reach different conclusions in good faith.
Where the job is large enough to matter, getting one quote from each discipline is worth the time. Ask each of them what would make them recommend the other approach — the answer tells you a great deal about how they think.
What to ask a contractor
- What do you think is actually causing this?
- What would make you recommend a different approach than the one you are proposing?
- If I do the cheaper option now, what is the realistic expectation before I am back here?
- Is there anything that needs fixing that is not concrete work?
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 the repair-or-replace decision 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 problems almost never justify replacement on their own. If the concrete is sound and supported, appearance has cheaper answers.
- Functional problems are where the decision genuinely sits, and where it turns on one question: has the material failed, or has its support failed?
- Structural problems change who should be deciding. Once movement has begun travelling into the building itself, the sequence starts with somebody qualified to assess that, not with a price for flatwork.
- Material versus support is the whole decision. Crumbling edges, exposed aggregate and rough deteriorating crack faces say the material is spent. An intact slab sitting wrong says the ground moved.
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.
- Close photographs of the crack faces and the edges, because that is where material failure shows and where it is invisible in a wide shot.
- Whether the affected sections are intact or broken into pieces, stated plainly — it is the fact that most changes which options are open.
- Dated images across at least two seasons if the movement might still be active, since correcting a surface over moving ground buys a newer surface on the same ground.
- What has been done before and when. A repair that did not hold narrows the options honestly.
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.
- Movement has reached something structural rather than staying in the flatwork.
- The same area has been repaired before and has returned to the same condition.
- The problem is spreading to sections that were sound when you first looked.
- Nobody can offer an explanation for the cause, only a price for the symptom.
What not to assume
- That replacement is the thorough option and repair is the cheap one. Replacing sound concrete over unresolved ground is the expensive way to keep a problem.
- That repair is always less disruptive. Some corrections need the same access and preparation as a replacement.
- That a contractor recommending the larger job is overselling. On spent material it is the honest answer, and treating it as a tactic costs you a good contractor.
- That the decision can be made from photographs alone — including by this site. What is written here narrows the question; it does not answer it for your property.
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.
Concrete that is uneven does not automatically need replacing.
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
- Unevenness is a description of where the slab sits, which can change without the concrete itself deteriorating.
- Several repair categories exist specifically to correct position while leaving sound concrete in place.
- The condition of the concrete and the condition of what supports it can differ independently.
- Where a previous position correction was carried out and did not hold, that is evidence about whether the movement is still active.
Still to establish
- Void depth and extent
- Subgrade and compaction
- Whether damage is surface or full depth — partly, on your own
- What the concrete adjoins — partly, on your own
- Previous repairs — you can check this yourself
Why we say this, and when it may not apply
It is the most common assumption homeowners arrive with, and acting on it is expensive. Unevenness describes position; replacement addresses condition, and the two are separate questions.
What we had to assume
- That the concrete itself is structurally sound rather than broken through its depth.
- That whatever moved the slab can be identified and, where it is still active, addressed.
When this may not apply
- Where the slab has broken into multiple pieces that move independently, position correction has little to hold.
- Where the surface has deteriorated through its depth as well as moved, correcting position leaves the other problem.
- Where the concrete adjoins or supports part of the building, the question stops being a paving question.
What would change it
- Evidence that the slab is cracked through its full depth in more than one place.
- Evidence that the ground is still moving, which would undo a position correction.
- Finding that the slab is tied into a foundation rather than independent of it.
- Finding that a previous correction was already tried here and did not hold.
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
Can I trust a contractor who only offers one method?
Usually, yes — specialisation is normal and often means they are good at it. What you cannot get from them is a neutral comparison, because they can only sell you one side of it. Ask them directly what would make them tell you to do something else. A good one will have a clear answer.
How many quotes should I get?
For anything substantial, three is a reasonable norm, and it is more useful when they are not all from the same discipline. Two leveling quotes and one replacement quote tell you more than three leveling quotes.
Work it out, or judge the quote
Repair or replace tool
Ten questions about what you can see, and the options your answers rule out.
Open it →Estimate decoder
Work through one proposal item by item: what it states, what is unclear, and what to ask before signing.
Open it →Freeze–thaw and soil risk guide
How water, freezing, soil movement and compaction damage slabs — and how to tell which one you have.
Open it →Related guides
Leveling vs replacement
When lifting is the smart economy and when it is a deposit on a job you will still do.
Read more →Resurfacing vs replacement
When a new surface is genuine value and when it is a cosmetic delay.
Read more →Common concrete problems
Start here: match what you are seeing to what it usually means and what it usually needs.
Read more →How to compare quotes
Make different-looking quotes comparable before you compare the totals.
Read more →Questions to ask a contractor
The questions that separate a diagnosis from a sales call — organised by what you are buying.
Read more →