Sandstone Patio Cleaning

Why sandstone needs care

Sandstone is made of sand grains bonded together. Its surface can be worn away by harsh cleaning, and it absorbs water, stains and dirt. High pressure can erode the surface and the pointing between slabs.

Common problems

Green algae and moss in shaded areas, black spots of lichen, weeds in joints, organic staining from leaves and general grime. Sandstone can also show iron staining from fertilisers or furniture.

Gentle cleaning

Sandstone is cleaned with suitable solutions, brushing and controlled rinsing. Pressure is kept low to protect the surface and joints. Acid-based cleaners can damage some sandstone and are avoided unless known to be suitable.

Black spot

The small black spots common on sandstone are usually lichen. They are stubborn and often fade gradually after treatment rather than disappearing immediately.

Joints and pointing

Weeds and moss in joints are removed. Washed-out joints may need re-pointing after cleaning.

Keeping it clean

Sweeping regularly, clearing leaves and improving drainage on shaded areas all help. Our slippery patio guide explains safety.

Indian sandstone

Much of the sandstone laid in UK gardens in recent decades is imported Indian sandstone. It comes in many colours, from buff and grey to multicoloured. It is still a sandstone and needs the same gentle approach. Some colours show algae and lichen more than others.

Riven and sawn finishes

Riven sandstone has a naturally split, textured surface that holds dirt and algae in its ridges. Sawn sandstone is smooth and cleaner looking but can be more slippery when green. Each needs brushing suited to its texture.

Sealing sandstone

Sealers can help reduce staining and slow algae, but they change the surface slightly and need reapplying over time. Sealing must be done on clean, dry stone. Ask for advice on whether sealing suits your patio.

Shaded patios

Patios under trees or beside walls stay damp longer and grow algae and moss quickly. Improving drainage, trimming overhanging plants and sweeping regularly all help. Shaded areas may need cleaning more often than sunny ones.

Furniture and pot stains

Metal furniture legs can leave rust stains, and plant pots leave rings of algae and mineral marks. Moving pots occasionally and using feet under them reduces staining. Some rust marks may not lift completely from porous stone.

Patios after winter

Spring is a natural time to clean patios after the damp months, when algae has built up and the patio is about to be used again. Our spring exterior checklist covers other jobs.

Patio drainage

Patios should fall slightly away from the house so water drains off. Where water pools, algae grows faster and stains build up. Cleaning can reveal where pooling happens, but fixing the fall is a landscaping job.

A step-by-step view of a sandstone clean

First, furniture and pots are moved and loose debris is swept away. Weeds and moss are lifted out of the joints by hand. A cleaning solution suited to sandstone is applied and left to work on algae and organic staining, then the surface is brushed to suit its texture, whether riven or sawn. Rinsing is done at controlled pressure so the surface and pointing are not eroded. Finally, any joints that have washed out or were already loose are noted so you can decide whether to have them re-pointed.

Lichen black spots are treated during the clean but often keep fading for weeks afterwards. That is normal for sandstone and worth knowing before you judge the finished result on the day.

Paths and steps too

Sandstone paths, steps and garden walls collect the same algae and lichen as patios. They are cleaned in the same gentle way and can be included in the same visit.

Get a quote

Send a photo of your patio. Quotes are free across Hampshire, Surrey and Sussex. See patio cleaning.