Key Takeaways
- A patio is four layers: the ground, a compacted sub-base, a bedding layer and the surface. Nearly every patio that doesn’t settle right has failed in one of the three layers below.
- Paving slabs, block paving, loose gravel and poured concrete are the four surfaces worth choosing between for a patio, and each one has it’s weak point. The sound way to choose is to pick then one you would rather live with.
- A patio needs a fall away from the house and a finished level that sits safely below the damp-proof course. Correcting the ground first beats trying to drain water that has been sent the wrong way.
- Patio quotes differ because of what sits underneath and how hard the ground is to reach, not because of the surface materials. Two quotes for the same area can be thousands apart on groundwork alone.
I used to get asked to look at more patios than I get asked to build from scratch. The surface looked fine for a summer, then a slab started to rock, or a corner holds water, a run of joints suddenly washed out. The owner wants to know what went wrong with the surface, but it nearly never went wrong on the top.
A patio is a small building project that happens to be flat, and the part that decides whether it lasts is the part you fill in before the nice bit goes on. This page is the map; if you want to know how it all comes together, my build guides carry the numbers.
What a patio is actually made of
A patio is a layered structure and the surface is only the top layer of four. Under it sits a bedding layer the surface is laid on, then a compacted sub-base (a crushed stone layer, usually MOT Type 1, that spreads the load and stops the surface sinking), then the natural ground, dug down far enough to fit everything in.
Each layer has one job. The ground has to be firm and free of anything soft. The sub-base carries the weight and stays put when wet. The bedding gives the surface something even to sit on. The surface is the only layer you see, and on most DIY builds it is the only one that gets any attention. That is the wrong way round. The depths, the materials and how much to order for a solid foundation are in my sub-base guide, with a sub-base calculator for the tonnage.
Choosing your surface: slabs, block paving, gravel or concrete
The four surfaces worth comparing for a UK patio are paving slabs, block paving, loose gravel and poured concrete, and the useful question is not which lasts longest. It is which failure you would rather deal with.
| Surface | Look | Skill to lay | How it fails | Fixing it |
|---|---|---|---|---|
| Paving slabs | Clean, large format, the classic patio | Moderate. Bedding and levels take practice | A slab rocks or sinks where the bed under it was thin | Lift the one slab and relay it |
| Block paving | Small units, patterns, takes curves well | Moderate to high. Lots of cutting on curves | Joints wash out, edges spread if not restrained | Top up joints, refix the edge |
| Loose gravel | Informal, cheap, easy to change later | Low. Most of the work is the base | Migrates, thins out, weeds through a poor membrane | Rake, top up, replace the membrane |
| Poured concrete | Seamless, any shape | High. One chance to get it right | Cracks, and the crack is permanent | Overlay, or break out and start again |
Slabs and blocks can be lifted and put right one piece at a time, which is why I lean toward them for most gardens. Concrete cannot. Gravel is the easiest to live with and the easiest to change your mind about, and it is what I would put in a garden that is still being worked out. I have written the two builds in full: the gravel patio, from excavation to the hose test, and laying slabs on a semi-dry sand and cement bed.
How big it should be, and where to put it
A patio should be sized around the furniture and the people walking round it, not around the slabs. The classic mistake is a patio that fits the table and chairs exactly, so nobody can push a chair back without stepping onto the lawn. Allow a metre of clear space behind every seat that gets used.
Position is about sun and about the house. A patio that catches evening sun gets used; one in permanent shade becomes the place the bins live. And a patio hard against the house brings the levels question straight into play, which I cover below. Small gardens are the trap: paved wall to wall they look smaller, not bigger, because the eye reads the paving straight into the fence. Leave planting around it.
What sits underneath, and the edges that hold it
The layers under a patio decide whether it is still level in five years, and they are the part I see skipped most often. A sub-base of compacted MOT Type 1 does the structural work, spreading every footstep and table leg across the ground rather than letting it punch through. On a loose-surface build a membrane goes over it to keep base and surface apart.
Then the surface needs holding in. Slabs and blocks creep sideways under load unless the edge is restrained, and gravel simply walks off the sides. That restraint is edging, and my garden edging guide covers what to use where. I am not giving you the depths here, because they change with the surface and the ground, and the build guides carry them properly. What I will say is that, currently, this is the half of the job we supply: MOT Type 1 for the sub-base, grano dust and ballast for the bedding layer, as well as decorative stone for the top of a gravel patio. Get this layer right and the surface has a chance.
Levels, and where the water goes
A patio has to shed water away from the house, and its finished level has to sit safely below the damp-proof course (the barrier in the wall that stops ground moisture rising into the house). Get either wrong and you have built a device for putting water into your own kitchen wall.
The mistake I see most is people solving this with drainage instead of levels. If the ground slopes toward the house, correct the ground. Do not lay the patio on the slope and hope a channel drain catches it. Drains block. Falls do not. Where the whole patio cannot fall away from the house, water has to be collected and sent somewhere it can soak, which is where a soakaway or a french drain comes in. The fall figures themselves are in the build guides.
Keeping a patio looking right
Patio maintenance is three jobs: keeping the joints filled, keeping the surface clean, and stopping weeds and moss getting a hold. None is difficult. All get worse if ignored for a year. Sand-filled joints want topping up in the first few months while they settle. A pressure washer is fine once they have firmed up, but aimed into a joint it blasts the sand straight out, so keep the lance flat. Sealing is a choice, not a requirement, and close to irreversible, so I leave a new patio through one winter before deciding. Cleaning, sealing and weed control each get their own article in time.
Making it feel part of the garden
A patio looks finished when something softens its edges. A bare rectangle of paving against a lawn reads as a car park; the same rectangle with a gravel margin and planting spilling over the edge reads as a garden. That is the whole trick. Gravel is my favourite way to do it, because it ties the paving to the beds and takes plants happily. Lighting along the edge earns its keep on autumn evenings. Pots do the rest. A raised bed does the same job on a bigger scale, as long as the water draining out of it has somewhere to go, and raised beds on a patio shows how.
Doing it yourself, or getting someone in
A patio is a realistic DIY job for someone reasonably fit who will do the groundwork properly, and a poor one for anyone hoping to skip it. The digging and the sub-base are the hard, dull, decisive work. Laying the surface is the reward.
Be realistic about time: what a two-person crew finishes in days takes a weekend DIYer a couple of months. If you are getting quotes, know why they differ. Access, what has to come out first, how deep the ground goes and drainage move the price far more than the slabs. And a contractor free this week is free for a reason; a good one is booked four to twelve weeks out. When it is finished, check it. A dip you can see under a straightedge is grounds for a conversation before the final payment, not after.
Next Steps
Pick your surface first, then read its build guide: the gravel patio or slabs on dry mix. Then price the layers underneath, because that is where the money and the longevity both sit. We carry the MOT Type 1, grano dust and ballast for the base and bed, and limestone chippings for a gravel surface, delivered on a pallet to the kerb.
If you would rather talk the sub-base and bedding materials for your patio through with a person, ring Outdoor Aggregates on 0330 043 7585. The office is open 7am to 7pm, seven days a week.
Have you ever laid a patio yourself, or had one laid? Which surface did you go for, and how has it held up? Let us know in the comments.
FAQs
Can a beginner lay a patio?
A beginner can lay a patio, and a small slab or gravel patio is a good first hard-landscaping job, provided the groundwork gets the same effort as the surface. The base is where beginners cut corners and where it then fails.
What should you put under a patio?
A patio needs a compacted sub-base of crushed stone, usually MOT Type 1, with a bedding layer on top for slabs or a membrane for gravel. Soil alone is never enough, however firm it looks dry.
Can you lay a patio directly on soil?
A patio laid directly on soil moves within a year, because soil softens when wet and lets the surface sink unevenly. A compacted sub-base is what stops that.
What is the cheapest patio to install?
A gravel patio is the cheapest patio to install, because the surface is inexpensive and the skill needed is low. The base still has to be done properly, so the saving is in the top layer, not the whole job.
What are the most common patio mistakes?
The most common patio mistakes are a thin or missing sub-base, no fall away from the house, and a finished level too close to the damp course. All three are invisible on the day the patio is finished and obvious a year later.