How to plan a concrete path, patio or driveway
Concrete is made up of cement, aggregate (particles of stone) and sharp sand. When you mix these ingredients with water, they bind into a solid, hard material. In different proportions, they produce concrete of different strengths for different uses.
It's important to get the proportions right. If there's too much aggregate, you'll struggle to get a satisfactory finish. And too much sand will make the mix weak, so that the finished surface could be damaged by the elements.
Concrete begins to harden after about two hours, and then becomes unworkable. But it doesn't become really strong for several days, and continues to harden as long as there's some moisture in it.
Read our helpful new buying guide for cement, mortar and concrete
Designing with concrete
To make sure that your concrete is strong enough, you'll need to take a number of factors into account when designing your path, pad or drive.
- The type of mix will be decided by what the concrete will be used for (see the table for more details).
- The thickness of the concrete is determined by the weight it'll be supporting. A pad for a lightweight wooden shed would only need to be 100mm deep. But for a stone, brick or block garage, you'd need a 150mm sub-base of compacted hardcore and a 125mm concrete pad. Also, the edges of this pad would need to be deeper (at least 200mm) to support the walls.
- The surface of the concrete must form a slight slope, so that water drains off. It should slope away from buildings or (in the case of a slab used to site a shed) away from the door.
- When it's laid against the wall of your house, the surface must be at least 150mm below the damp-proof course.
- In an area that has to cope with heavy weights (such as a driveway), you should reinforce concrete with a steel grid at half its depth.
Top tip - Easy mix
Concrete mix is an ideal option if you don't want to combine the ingredients yourself, or you only need a small amount of concrete.
Mixing concrete by hand
Mixing concrete by hand is only really an option for small amounts. You prepare it in the same way as mortar, mixing it thoroughly and methodically until it's an even consistency - neither too dry nor too sloppy. When you pick up a shovelful it should stay on the shovel, and when you drop it onto the sub-base it should spread slightly but retain some shape.
Using a mixer
Start by pouring about a quarter of a bucket of water into the mixer. Add half the aggregate and half the sand (or half the all-in aggregate), and all the cement. Then check the mix to see if you need to add more water. Add the rest of the aggregate (and sand, if you're using it), and more water if necessary. If you find it difficult to assess how much is in a shovelful, try using buckets instead . If the final mix is too sloppy, add more aggregate and cement in proportion. An average-sized mixer will take 12-14 shovelfuls of aggregate and two to three shovelfuls of cement.
Ready-mixed concrete
If you're planning to lay a large area of concrete or you're short on time, ready-mixed concrete is well worth thinking about. Depending on how easy it is to get to your site, the concrete will be delivered in lorries and either poured directly on to the area or wheelbarrowed from the lorry to the site. It's a much more expensive way of buying concrete, but it does cut down on labour enormously - and you can get any quantity delivered. If you decide to use ready-mixed concrete, you'll need to ensure that everything is organised before the lorry arrives and that help is on hand. You order ready-mixed concrete by the cubic metre: it's sensible to add 10% for wastage and specify the job you're doing, so the right mix can be prepared.
Concrete mixes
| Ingredients | Amounts required for approx. 1 cubic metre of concrete |
| Paving mix (strong mix suitable for exposure to all weathers, including frost), using separate aggregate 1 part cement 1.5 parts sharp sand 2.5 parts 20mm coarse aggregate | 16x25kg bags 0.5 cubic metre 0.75 cubic metre |
| Paving mix (strong mix suitable for exposure to all weathers, including frost), using all-in aggregate 1 part cement 3.5 parts all-in aggregate | 16x25kg bags 1 cubic metre |
| Foundation or footing mix (and for concreting in fence posts), using separate aggregate 1 part cement 2.5 parts sharp sand 3.5 parts 20mm coarse aggregate | 11.2x25kg bags 0.5 cubic metre 0.75 cubic metre |
| Foundation or footing mix(and for concreting in fence posts), using all-in aggregate 1 part cement 5 parts all-in aggregate | 11.2x25kg bags 1 cubic metre |
| For garage or garden shed bases (not exposed to weather), using separate aggregate 1 part cement 2 parts sharp sand 3 parts 20mm coarse aggregate | 12.8x25kg bags 0.5 cubic metre 0.75 cubic metre |
| For garage or garden shed bases (not exposed to weather), using all-in aggregate 1 part cement 4 parts all-in aggregate | 12.8x25kg bags 1 cubic metre |
Estimating the amount
Working out how much concrete you need calls for a bit of basic geometry. Measure the surface area of your site by multiplying the length by the width (in metres). Then multiply that figure by the depth or thickness you need (as a fraction of a metre) to get the volume in cubic metres.
In practice, figures are rounded up and about 10% added for wastage. For example: (width) 2m x (length) 6m x (depth) 0.15m = 1.8 cubic metres, which you'd round up to 2 cubic metres of concrete.
If your site is circular, use the formula ?r2 (? = 3.14 and r2 = the radius of the circle squared). Multiply them together to get the surface area, then multiply that number by the depth of the concrete needed to get the volume. For example: (?) 3.14 x (radius) 2m x (radius) 2m x depth 0.15m = 1.884 cubic metres of concrete. Rounded up, you would need 2 cubic metres of concrete.
Irregular shapes
To work out the volume of concrete you need for an irregularly-shaped site, draw it accurately and to scale on graph paper. Each square should represent one square metre of the site. Count all the squares you're covering, and roughly add up the part squares. Then multiply that total by the depth of the concrete, and round the figure up by 10%.
Designing with concrete
To make sure that your concrete is strong enough, you'll need to take a number of factors into account when designing your path, pad or drive.
- The type of mix will be decided by what the concrete will be used for (see the table for more details).
- The thickness of the concrete is determined by the weight it'll be supporting. A pad for a lightweight wooden shed would only need to be 100mm deep. But for a stone, brick or block garage, you'd need a 150mm sub-base of compacted hardcore and a 125mm concrete pad. Also, the edges of this pad would need to be deeper (at least 200mm) to support the walls.
- The surface of the concrete must form a slight slope, so that water drains off. It should slope away from buildings or (in the case of a slab used to site a shed) away from the door.
- When it's laid against the wall of your house, the surface must be at least 150mm below the damp-proof course.
- In an area that has to cope with heavy weights (such as a driveway), you should reinforce concrete with a steel grid at half its depth.
Top tip - Easy mix
Concrete mix is an ideal option if you don't want to combine the ingredients yourself, or you only need a small amount of concrete.
Mixing concrete by hand
Mixing concrete by hand is only really an option for small amounts. You prepare it in the same way as mortar, mixing it thoroughly and methodically until it's an even consistency - neither too dry nor too sloppy. When you pick up a shovelful it should stay on the shovel, and when you drop it onto the sub-base it should spread slightly but retain some shape.
Using a mixer
Start by pouring about a quarter of a bucket of water into the mixer. Add half the aggregate and half the sand (or half the all-in aggregate), and all the cement. Then check the mix to see if you need to add more water. Add the rest of the aggregate (and sand, if you're using it), and more water if necessary. If you find it difficult to assess how much is in a shovelful, try using buckets instead . If the final mix is too sloppy, add more aggregate and cement in proportion. An average-sized mixer will take 12-14 shovelfuls of aggregate and two to three shovelfuls of cement.
Ready-mixed concrete
If you're planning to lay a large area of concrete or you're short on time, ready-mixed concrete is well worth thinking about. Depending on how easy it is to get to your site, the concrete will be delivered in lorries and either poured directly on to the area or wheelbarrowed from the lorry to the site. It's a much more expensive way of buying concrete, but it does cut down on labour enormously - and you can get any quantity delivered. If you decide to use ready-mixed concrete, you'll need to ensure that everything is organised before the lorry arrives and that help is on hand. You order ready-mixed concrete by the cubic metre: it's sensible to add 10% for wastage and specify the job you're doing, so the right mix can be prepared.
Concrete mixes
| Ingredients | Amounts required for approx. 1 cubic metre of concrete |
| Paving mix (strong mix suitable for exposure to all weathers, including frost), using separate aggregate 1 part cement 1.5 parts sharp sand 2.5 parts 20mm coarse aggregate | 16x25kg bags 0.5 cubic metre 0.75 cubic metre |
| Paving mix (strong mix suitable for exposure to all weathers, including frost), using all-in aggregate 1 part cement 3.5 parts all-in aggregate | 16x25kg bags 1 cubic metre |
| Foundation or footing mix (and for concreting in fence posts), using separate aggregate 1 part cement 2.5 parts sharp sand 3.5 parts 20mm coarse aggregate | 11.2x25kg bags 0.5 cubic metre 0.75 cubic metre |
| Foundation or footing mix(and for concreting in fence posts), using all-in aggregate 1 part cement 5 parts all-in aggregate | 11.2x25kg bags 1 cubic metre |
| For garage or garden shed bases (not exposed to weather), using separate aggregate 1 part cement 2 parts sharp sand 3 parts 20mm coarse aggregate | 12.8x25kg bags 0.5 cubic metre 0.75 cubic metre |
| For garage or garden shed bases (not exposed to weather), using all-in aggregate 1 part cement 4 parts all-in aggregate | 12.8x25kg bags 1 cubic metre |
Estimating the amount
Working out how much concrete you need calls for a bit of basic geometry. Measure the surface area of your site by multiplying the length by the width (in metres). Then multiply that figure by the depth or thickness you need (as a fraction of a metre) to get the volume in cubic metres.
In practice, figures are rounded up and about 10% added for wastage. For example: (width) 2m x (length) 6m x (depth) 0.15m = 1.8 cubic metres, which you'd round up to 2 cubic metres of concrete.
If your site is circular, use the formula ?r2 (? = 3.14 and r2 = the radius of the circle squared). Multiply them together to get the surface area, then multiply that number by the depth of the concrete needed to get the volume. For example: (?) 3.14 x (radius) 2m x (radius) 2m x depth 0.15m = 1.884 cubic metres of concrete. Rounded up, you would need 2 cubic metres of concrete.
Irregular shapes
To work out the volume of concrete you need for an irregularly-shaped site, draw it accurately and to scale on graph paper. Each square should represent one square metre of the site. Count all the squares you're covering, and roughly add up the part squares. Then multiply that total by the depth of the concrete, and round the figure up by 10%.
Frequently Asked Questions
- Is it cheaper to do a concrete patio?
Generally, a concrete patio can be cheaper than many alternatives, depending on the size, finish and whether you do it yourself. Material costs for basic concrete are typically low, but excavation, sub-base, reinforcement and labour add to the total. Decorative finishes, drainage, or complex shaping increase costs, while DIY installation reduces labour but needs skill and tools. Get quotes for materials and trades, and compare with paving slabs or resin options to decide what suits your budget.
- Can I lay my own concrete patio?
Yes, you can lay your own concrete patio. It is a manageable DIY job if you have basic DIY skills, the right tools and time for proper preparation, mixing and finishing. Key steps include marking out, excavating and compacting a firm sub-base, installing formwork and any reinforcement, pouring and levelling the concrete, then finishing and curing correctly. Check for underground services, allow adequate drainage, and follow local guidance or seek professional advice for large or sloping areas.
- Is it cheaper to build a deck or a concrete patio?
Generally a basic timber deck is often cheaper to install than a concrete patio, but total cost depends on materials, size and labour. Decks can be less expensive for small areas and uneven ground, while concrete needs more groundwork, formwork and labour but can be cheaper for large, low-maintenance areas. Consider drainage, ground preparation, ongoing maintenance and expected lifespan when comparing overall cost.
- What is the lifespan of a concrete patio?
A well-installed concrete patio typically lasts 25 to 50 years. Longevity depends on factors such as the quality of the subbase, correct mix and placement, adequate reinforcement and jointing, drainage, and how it is used. Regular maintenance, like sealing, cleaning, and repairing cracks promptly, helps extend life, while heavy vehicle use, poor drainage or freeze thaw cycles can shorten it. Proper installation and upkeep give the best results.