Porcelain is better if you want a patio that stays clean and uniform with little upkeep, and it costs £140–£210 per m² laid in the West Midlands. Indian sandstone, at £110–£160 per m², is cheaper and looks more natural, but it weathers, marks and needs more cleaning. Both last well on a proper base, which matters more than the slab.
The rest of this guide covers what each costs, why porcelain needs a primer, how each should be laid, which is more slippery, how they age and which gives better value over time. Prices are from the site's patio cost guide.
How much does each cost?
Prices are supplied and laid on a new base, with waste taken away.
| Indian sandstone | Porcelain | |
|---|---|---|
| Per m², laid | £110–£160 | £140–£210 |
| About 22m² on an old lawn, including digging out | £2,640–£3,920 | £3,300–£5,020 |
On a medium patio, porcelain comes out roughly £660–£1,100 dearer. Lifting old slabs or block paving first adds £15–£25 per m² for either material, and old concrete £20–£35 per m². New patios start at about £1,500.
Part of the porcelain premium is the slab, and part is labour. Porcelain is thin and very hard, so it takes longer to cut, and every slab needs a primer on the back so it bonds to the mortar.
Why does porcelain need a primer or slurry?
Porcelain is fired to a very dense body that absorbs almost no water, typically 0.5% or less, which is what the ceramic tile standard BS EN 14411 sets for porcelain. That density is why it resists stains and moss, but it also means mortar cannot key into the back of the slab the way it soaks into sandstone.
To make the bond, installation guidance for outdoor porcelain calls for a bonding primer or slurry brushed onto the back of each slab and laid while it is still wet onto a fresh, full mortar bed. If the primer is skipped, or allowed to dry before the slab goes down, the slab can come away from the bed. That is the usual cause behind forum questions about porcelain slabs that rock or lift after a winter.
Sandstone is porous, so it bonds to mortar more readily. Some installers also prime the back of sandstone slabs, particularly paler stones, to help stop staining coming through from the bed.
What base and bedding does each need?
The base is the same for both. The old surface is dug out, a crushed-stone sub-base is laid and compacted, and each slab goes onto a full mortar bed, not five dabs at the corners and centre. Dabs leave voids that let slabs rock and crack and let water sit underneath, whichever material you choose.
The differences are in the detail:
- Porcelain is usually thinner and made to a consistent size and thickness, so the bed has to be flat and even. Any unevenness shows as lipped edges. Joints are filled with a specialist jointing compound suited to porcelain.
- Indian sandstone varies in thickness from slab to slab, especially hand-cut stone, so each one is bedded individually to bring the tops level. Joints are usually mortar or a brush-in compound.
Whatever the material, the patio must fall gently away from the house and sit low enough below the damp-proof course. The patios service page explains the falls and the 150mm rule. Ask for the sub-base depth and bedding method in writing before work starts; patios fail for the same reasons as cheap drives, covered in why cheap driveways fail.
Which is more slippery when wet?
It depends on the finish, not just the material. Riven Indian sandstone has a naturally textured surface with good grip. Porcelain ranges from smooth to textured, so check that the slabs are an outdoor grade with a published slip rating.
The Health and Safety Executive's guidance on slip resistance gives a useful yardstick. A pendulum test value of 36 or more is low slip potential, 25 to 35 moderate, and 24 or under high. On the R-scale often printed on tiles, HSE notes that surfaces rated R9, and in some cases R10, will be slippery when wet. Compare the wet figures if they are published.
Both materials become slippery when algae and moss build up, which is mainly a problem in shade. Sandstone's textured surface holds more growth than smooth porcelain, so it tends to need cleaning more often.
Does Indian sandstone fade?
Natural stone changes with weathering. Sandstone colours often mellow and soften over the years, and some stones lighten or pick up marks from leaves, rust from furniture or spills. Many people like that aged look; others find it patchy. Sealing can help resist staining, but it needs renewing and some sealers change the appearance.
Porcelain's colour is part of the fired slab, so it generally holds its look far better, and it shrugs off most stains. The trade-off is that it looks the same in twenty years as on day one, which some people find less characterful.
Which is better value in the long run?
Porcelain costs more to lay but less to keep looking good. Sandstone usually needs a clean every year or two in a shady garden, and cleaning a patio costs £4–£8 per m², or £10–£20 per m² with re-sanding and sealing, with a minimum of about £350 a visit. See driveway and patio cleaning.
On a 22m² patio, the extra £660–£1,100 for porcelain is roughly the cost of two or three professional cleans of sandstone. If you would clean it yourself, or like how stone ages, sandstone is the better value. If you want low upkeep and a crisp look, porcelain earns its premium over time. No reliable source shows either adding more to a house's value than the other.
Can I mix porcelain and sandstone?
Yes, and it is common, for example a porcelain main area with a sandstone or setts border, or a sandstone patio with porcelain steps. Because the two are laid differently, the specialist needs to plan the levels so the finished surfaces meet flush, and use bedding and jointing that suit both. Mention a mix when you ask for a price, since it affects cutting time.
Questions
Why are my porcelain slabs coming loose?
The usual causes are a missing or dried-out primer on the back of the slab, or slabs laid on dabs or a dry mix instead of a full wet mortar bed. A loose slab normally has to be lifted, cleaned off, primed and relaid on a fresh bed.
Does Indian sandstone need sealing?
It is optional. Sealing can help light sandstone resist staining and make it easier to clean, but most sealers need renewing every few years and some change the colour or add a sheen. Leaving it unsealed and cleaning it when needed is also a reasonable choice.
Does porcelain paving crack in frost?
Porcelain's very low water absorption means there is little water in the slab to freeze, so it generally copes well with frost. Cracks in a porcelain patio usually come from voids under the slab or a weak base rather than the cold.