Why Sandstone Earns Its Place in British Gardens

Sandstone has become the default choice for patios across the UK for good reason. It is a natural stone, so every slab is slightly different, and it costs a fraction of what you would pay for granite or porcelain while still feeling solid underfoot. Most sandstone sold here is riven, meaning the surface has a natural split that gives grip even when wet — a real advantage in a country where a patio can be slick with rain from October to March.

It also handles frost better than many people expect, provided you buy a decent grade. Sandstone is porous, and water that soaks in can freeze and expand, which is what causes flaking and spalling over time. Dense, well-graded stone from a reputable supplier will shrug off most winters. Cheap, soft, heavily salt-laden imports will not. If you are offered stone at a price that seems too good, ask about its water absorption and where it was quarried.

Thickness: The Number That Decides Your Build-Up

Thickness matters because it dictates how the patio is built, not just how it looks. For a patio laid on a full mortar bed over a compacted sub-base, most calibrated sandstone packs come in at 18mm to 22mm, and that is perfectly adequate. The stone is not carrying the load on its own — the sub-base and bedding do that.

• 18–22mm: the standard calibrated patio pack. Fine for pedestrian use over a solid, well-compacted base of around 100mm MOT Type 1.
• 25–40mm: thicker riven stone, often sold as "project packs" or hand-cut. More forgiving if the base is slightly uneven, and a good choice where a vehicle might occasionally cross.
• 20mm and up: the practical minimum if you plan to lay on adjustable pedestals, with 30mm giving a more stable, longer-lasting finish.

Check the thickness of individual slabs before you start. Even in a "calibrated" pack you will find the odd slab a couple of millimetres out, and bedding those down evenly is much easier if you sort them first.

Colour and Character: Planning for Natural Variation

No two crates of sandstone look identical, and that is part of the charm — but it does need managing. Colours are usually sold under names like buff, grey, camel, autumn brown or rainbow, and the variation within a single pack can be dramatic. A slab that looks pale and sandy in the crate may dry to a much deeper tone once laid.

A few habits will save you a lot of regret:

• Open three or four crates at once and blend slabs from each as you lay, rather than working through one crate at a time.
• Lay a dry run of the main area first so you can see how the tones sit together before any mortar is mixed.
• Wet the stone with a hose to see its true colour. Dry sandstone and wet sandstone can look like two different products.
• Expect the patio to lighten slightly over the first year as surface dust and quarry residue weather away.

If you want a calm, uniform look, choose a sawn or honed finish in a single colour — but remember that smooth surfaces become slippery when wet, so keep them out of shaded, moss-prone corners.

Sealing: When It Helps and When It Doesn't

Sealing is the subject that causes the most confusion. Sandstone does not need sealing to survive a British winter, and plenty of patios go decades without it. What a good impregnating sealer does is slow down staining from bird droppings, barbecue fat, red wine and leaf tannins, and make routine cleaning easier.

What you must avoid is a film-forming sealant that sits on the surface and traps moisture underneath. In a freeze-thaw climate that is a recipe for flaking. Choose a breathable, impregnating sealer instead.

• Seal only when the stone is thoroughly dry — usually after a run of two or three dry days.
• Apply two thin coats rather than one thick one, and wipe off any excess before it dries.
• Do not seal in direct sunlight or when rain is forecast within 24 hours.
• Reapply every three to five years, or when water stops beading on the surface.

Many installers now pre-seal before pointing, which makes cleaning off cement haze or resin residue far easier. If you are using a resin jointing compound, follow its guidance carefully — some require the stone to be sealed first, others do not.

Weatherproofing the Details

Sandstone copes with British weather when the details around it are right. Build in a fall of about 1:80 away from the house so water runs off rather than pooling, and make sure the sub-base drains rather than forming a bowl. Point the joints properly; wide, crumbly mortar joints hold water and grow moss.

An annual scrub with a stiff brush and warm soapy water in spring will keep algae at bay, and a diluted patio cleaner can be used on stubborn green patches — never a pressure washer on full blast, which strips the surface and opens up the pores. Do those small jobs and a sandstone patio will quietly outlast most of the plants around it.