How to Tell If Your Patio Needs Repointing or Just a Clean (Before You Pay for the Wrong Job)

We get a fair number of calls that start the same way: “My patio looks awful, how much to sort it out?” It’s a reasonable question, but it’s also the wrong one to lead with, because a dirty-looking patio and a patio with failing joints are two completely different jobs, priced completely differently, and it’s genuinely hard to tell which one you’ve got from a few feet away. Before you get quotes, here’s how to work out which category your patio actually falls into, so nobody talks you into paying for a repair you don’t need, or a quote you got misses a job you do.

Why This Matters Before You Even Call Anyone

A clean addresses what’s on the surface: algae, black spot, general grime, faded colour. Repointing addresses what’s between the slabs: the mortar or sand that holds them in place and stops water getting underneath. They’re priced very differently, and, this is the bit that catches people out, a clean genuinely won’t fix failing joints, and paying for full repointing when your patio only needed a wash is money you didn’t need to spend. Getting this wrong in either direction is how homeowners end up either under-quoted for the job they actually need, or upsold on repair work a good clean would have sorted.

Signs You Probably Just Need a Clean

• The surface looks dull, green, or has dark patches, but the joints between slabs still feel solid when you press on them.
• Slabs don’t move or rock underfoot, everything feels stable, just dirty.
• Discolouration is even across the patio rather than concentrated around specific joints or edges.
• Weeds are growing on the surface itself or in gaps that have clearly just collected windblown dirt, not in gaps where you can see the mortar has actually gone.

If that’s what you’re looking at, our patio cleaning service is the whole job, and our patio cleaning cost guide will give you a realistic figure before anyone even comes out.

Signs You’re Actually Looking at a Repointing Job

• You can see daylight or a visible gap where mortar used to be between slabs, rather than the joint just looking dark or dirty.
• A slab rocks, tips, or feels loose when you stand on one corner of it.
• Weeds keep coming back in the exact same joints no matter how often you clean or pull them, that’s usually a sign the mortar’s gone and there’s nothing stopping seed getting underneath.
• Water sits in a line along a joint after rain rather than draining away, which often means the pointing has sunk or cracked and is holding moisture instead of shedding it.
• You can push a screwdriver or a key gently into the joint and it crumbles away rather than meeting solid resistance.

Any of these on their own is worth a proper look. Several together usually means it’s time to book patio repointing rather than another wash.

The Screwdriver Test

This is the quickest way to tell the two apart yourself, and it takes about thirty seconds. Pick a joint that looks like it’s in the worst condition, and press the tip of a flat-head screwdriver or an old key into it with light pressure, no need to force it. If the mortar is sound, it’ll feel solid and won’t move. If it’s failing, it’ll crumble, flake away, or the screwdriver will sink in further than you’d expect with barely any pressure. Try this in two or three different spots around the patio, not just one, since joints often fail unevenly depending on drainage and sun exposure.

Why Black Spot Can Confuse the Diagnosis

One thing that trips people up: black spot (lichen) can look structurally alarming even when the joints underneath are perfectly sound, because it forms dark, crusty patches that some homeowners mistake for crumbling mortar. Our guide to patio black spot removal goes into how to tell the difference, it’s worth ruling this out before assuming you’re looking at a repointing job.

A Job That Illustrates This Well

A customer in Berkhamsted rang us convinced her whole patio needed re-laying, it looked patchy, dark, and a couple of slabs felt like they were lifting slightly at one corner. On inspection, about 90% of it just needed a proper clean and biocide treatment; the joints were sound everywhere except one shaded corner near a drainpipe, where the pointing had genuinely failed and let water sit underneath. That corner got repointed, the rest got cleaned and sealed, and the job came in at a fraction of what a full repoint would have cost. That’s a fairly typical split, in our experience, most patios are cleaning jobs with a small repointing job hiding in one corner, not the other way round.

What If It’s Both?

Often it is, at least in part, and that’s fine, it just changes the order of operations. Cleaning always comes first, because repointing over dirty, algae-covered joints means the new mortar won’t bond properly and will fail again quickly. Once the surface is clean, it’s also much easier to see exactly which joints need attention rather than guessing under a layer of grime.

When to Go a Step Further: Repointing vs Restoration

If you’ve worked through this and it’s clear you need more than a handful of joints redone, sunken slabs, widespread cracking, or a patio that’s more gap than mortar in places, that’s a different decision again, and one we’ve covered in detail in Patio Repointing vs Patio Restoration. Think of this post as the step before that one: work out whether you’re dealing with dirt or damage first, then, if it’s damage, that guide will help you work out how much of it.

What to Ask Before You Book Anyone

• Ask them to specify, in writing, whether the quote covers cleaning, repointing, or both, vague quotes are where most of the upselling or under-quoting happens.
• Ask what proportion of the patio they think needs repointing, not just whether it does, a full quote for a full repoint when only two joints have failed is worth questioning.
• Ask whether cleaning is included before repointing work, since it should be, for the bonding reason above.

The Honest Bottom Line

Most patios that “look terrible” are dirtier than they are damaged. Do the screwdriver test in a few spots, keep an eye out for movement and pooling water rather than just discolouration, and you’ll walk into any quote already knowing roughly which category you’re in, which is the best protection there is against paying for the wrong job.

Related Reading

If you’ve confirmed it’s a repointing job, see Patio Repointing vs Patio Restoration for the next decision. If it’s cleaning, our patio cleaning cost guide and common patio cleaning mistakes are worth a read. For dark staining specifically, see patio black spot removal, and if you’re still unsure, our signs it’s time to call local patio cleaners guide covers the broader warning signs.

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