--- title: "Patio Drainage & Levelling FAQs | Cambridge Patios" description: "Straight answers to the questions we get asked about patio drainage & levelling, problems, costs, suitability and what to expect." canonical: "https://www.cambridgepatios.co.uk/faq/patio-drainage-levelling" lastmod: "2026-10-05T11:28:40.315Z" --- # Patio Drainage & Levelling Questions Every question we get asked about patio drainage & levelling, answered straight. ## Problems & Symptoms ### Why is water pooling on my patio? Water pools when the surface fall runs toward the house or a low spot rather than away from it. This is usually caused by settlement, a poorly set original fall, or a sunken slab creating a hollow. Even a few millimetres of dip is enough to hold standing water after rain. ### How do I know if my patio needs levelling or drainage work? If water sits on the surface for more than an hour after rain, or runs toward the house wall, the fall is wrong and needs correcting. Visible dips, rocking slabs, or puddles that form in the same spot every time are the clearest signs. A survey will confirm whether the base or the surface is the root cause. ### Can a small dip really cause water to sit on the patio? Yes. A dip of as little as 10-15 mm across a slab is enough to hold a puddle. Water always finds the lowest point, so even a shallow hollow collects and holds standing water rather than shedding it to the edge. ### Could there be a problem with the base underneath? Yes, and it is a common cause of recurring pooling. If the sub-base has compacted unevenly, washed out, or was too shallow to begin with, the slabs above will keep moving regardless of how many times the surface is reset. A survey checks the base depth and condition before work is specified. ### What causes water to pool on a patio in the first place? The three main causes are an insufficient or reversed surface fall, sunken slabs creating low spots, and blocked or absent drainage at the patio edge. Clay-heavy ground that does not absorb water quickly can make all three worse, particularly after heavy rain. ### Can drainage and levelling solve a patio that sits on clay-heavy ground? Yes, with the right base specification. Clay does not drain freely, so the sub-base needs adequate depth and compaction to prevent movement, and the surface fall must direct water away efficiently. A channel drain at the edge can also help where clay ground stays saturated for extended periods. ## Is It Right for You? ### Will the corrected fall move water away from the house properly? Yes, provided the fall is set to a minimum 1:60 gradient away from the building, surface water drains clear of the house wall. This is the standard fall used when resetting patio slabs close to a property. A survey confirms the correct direction and gradient for your specific layout. ### Will the repair cover the whole patio or only the low spot? The scope depends on where the fall breaks down. If only one or two slabs have dropped, the repair is localised. If the gradient is wrong across a wider run, more slabs are reset to create a consistent fall. The survey defines the exact area before any work is quoted. ### Is this the right fix if the patio has settled over time? Yes. Gradual settlement is one of the most common reasons [patios](https://www.cambridgepatios.co.uk/) need re-levelling. Lifting the slabs, correcting the sub-base where needed, and re-bedding with the right fall restores the surface to a stable, draining condition. It is a more cost-effective route than full replacement in most settled patios. ### Is patio drainage needed on previously farmed land or wet ground? Yes. Previously farmed or consistently wet ground holds water close to the surface and can shift under load. A deeper, well-compacted sub-base is typically needed, and a perimeter or channel drain prevents surface water from saturating the base over time. A survey of the ground conditions is the right starting point. ## Comparing Your Options ### Will fixing the slope sort out both the level and the drainage? Correcting the fall addresses both issues at once in most cases. Once the surface sheds water consistently toward a drain or lawn edge, pooling stops and the level reads flat underfoot. Where a drain is blocked or absent, a channel or point drain may also be needed alongside the re-levelling work. ### Do you need to lift the whole patio, or just the problem area? Usually only the affected slabs need lifting, not the entire patio. If the fall is wrong across the whole surface, more slabs will need resetting to create a consistent gradient. A survey identifies exactly how far the problem extends before any lifting begins. ### Can you fix this without replacing the whole patio? In most cases, yes. Lifting and resetting the affected slabs with a corrected bed and fall is enough to solve pooling and uneven surfaces. Full replacement is only necessary when the base has failed across the whole area or the slabs themselves are cracked beyond reuse. ### Will a quick patch actually stop the dip coming back? A surface-only patch without addressing the bed underneath will not hold long-term. The slab will re-settle into the same void. Lifting the slab, correcting or compacting the base, and re-bedding properly is the only approach that prevents the dip returning. ### Do uneven patio slabs always need replacing? No. Slabs that are structurally intact can be lifted, the bed corrected, and the slabs re-laid. Replacement is only needed when a slab is cracked, spalled, or cannot be matched after damage during lifting. [Patio cleaning and repointing](https://www.cambridgepatios.co.uk/services/patio-cleaning-repointing-repair) can restore the finish once levels are corrected. ### Will levelling help if the patio has already started to move after freeze-thaw cycles? Levelling helps, but the base must be checked first. Freeze-thaw movement often means water has been sitting in the bed and expanding. Re-levelling without addressing the drainage that allowed water in will result in the same movement next winter. The survey identifies whether the base needs rebuilding before slabs are reset. ## How It Works ### How much digging and lifting will the job involve? Slabs are lifted and the bed beneath is re-graded or built up with fresh mortar or compacted sub-base material. The depth of work depends on how far the base has dropped. Most levelling jobs do not require deep excavation unless the sub-base itself has failed. ### Is it better to fix this now or can I leave it until next season? Leaving it risks further damage. Standing water accelerates joint erosion, and freeze-thaw cycles through winter force water into cracks and lift slabs further. A small levelling job now is considerably less disruptive than a full base repair after a second winter of movement. ### How do you check whether the patio is draining the right way? A spirit level and straight edge across the surface shows the direction and degree of fall. A hose test confirms where water travels in practice. The installer checks fall at multiple points to identify any localised low spots that a single reading might miss. ### Do you need extra drainage on a patio in Cambridge because of wet winter ground? Cambridge’s clay-heavy soils drain slowly, so surface water has fewer places to go in wet winters. A correctly set fall is essential, and in lower-lying areas a channel drain at the patio edge is often worth adding to handle peak rainfall without water backing up onto the surface. ### Why does water keep pooling on my patio after rain? The patio is likely falling the wrong way, the sub-base has settled unevenly, or there is no drain to take the water away. In some cases it is one low slab; in others the whole surface needs lifting and relaying with a correct fall away from the house. ### Do uneven slabs always need replacing? Not always. If the slabs are sound, they can usually be lifted and relaid with the base rebuilt beneath them. Replacement is only needed if the slabs themselves are cracked or badly worn. ### Can a single small dip really cause a drainage problem? Yes. Even a shallow low point holds water after rain and makes the surface feel uneven underfoot. If the fall is wrong across a wider area, the puddling will keep returning until the gradient is corrected. ### What happens if I leave the problem another season? Standing water against a house wall can breach the damp-proof course over time. Frost then widens any gaps in the sub-base, accelerating slab movement and making the eventual repair more extensive and more costly. ### How do you check whether levelling or drainage work is needed? A laser level maps the existing surface to identify fall direction, low spots and any areas of sub-base settlement. That tells the installer whether the fix is a single slab relay, a full regrade, or a drainage channel at the low edge. ### Will lifting the slabs damage them? Carefully lifted slabs in good condition can be relaid without damage. Each slab is assessed before lifting, and any that are cracked or too fragile to reuse are flagged, so you know before work starts. ## Guarantees & Peace of Mind ### Will the patio be safe to walk on when the work is done? Yes, once the mortar or bedding has cured fully and joints are set, the surface is safe to walk on. The curing time is confirmed on the day, typically 24-48 hours for mortar beds before normal foot traffic resumes. ### Will the repaired patio have any trip edges or uneven joins? A properly executed repair brings reset slabs flush with their neighbours, eliminating trip edges. The installer checks levels across joins before the mortar sets. Where a slab cannot be matched exactly due to wear or breakage, the options are discussed before work starts. ### Could lifting the slabs damage the patio further? Careful lifting carries minimal risk. Natural stone and porcelain slabs can crack if levered incorrectly, so the method matters. Any slabs identified as fragile or already cracked are flagged before lifting so you can decide whether to replace them. ### How do you make sure the fix does not just let the water pool again? The installer sets a consistent fall across the reset area, checks levels at every slab join, and confirms water tracks to the intended outlet before finishing. Where the base was the root cause, it is compacted or rebuilt to the correct depth so the slabs have a stable, uniform platform. ## Tell Us About Your Patio Project We schedule a site survey and quote excavation, sub-base, bedding and paving as separate lines, so there are no hidden groundwork costs. [Start Your Enquiry](https://www.cambridgepatios.co.uk/contact) ## Business details ### Contact - **Phone**: [07787 475312](tel:07787475312) - **Email**: [contact@cambridgepatios.co.uk](mailto:contact@cambridgepatios.co.uk) - **Based in**: Cambridge, Cambridgeshire, CB1 - **Enquiries**: [Send an enquiry](https://www.cambridgepatios.co.uk/contact) — We ask for your name, phone number, email and a message. ### Opening hours - **Monday**: 08:00 – 18:00 - **Tuesday**: 08:00 – 18:00 - **Wednesday**: 08:00 – 18:00 - **Thursday**: 08:00 – 18:00 - **Friday**: 08:00 – 18:00 - **Saturday**: 10:00 – 16:00 - **Sunday**: 10:00 – 16:00 [Business details](https://www.cambridgepatios.co.uk/about/business.md)