Sandstone Patio Cleaning and Re-Jointing in Oxford
Sandstone patio cleaning and repointing in Oxford: progressive black spot removal, loose slab repairs, Chiltern EverGuard™ and a complete resin repoint.
EXPERT CARE. LASTING RESULTS.
Before · The day before the works
Sandstone Patio Cleaning and Repointing
Princes Risborough, Buckinghamshire
Black spot treated within the stone, the back steps relaid and repointed, and the whole patio protected with Chiltern EverGuard™.
Chiltern Surface Cochilternsurface.co.uk
EXPERT CARE. LASTING RESULTS.
The Brief
The project at a glance
Client
Peter Johnson
Location
Princes Risborough, Buckinghamshire
Surface
Indian sandstone, approximately 120 m²
Areas
Rear patio, hot tub surround, French-door steps, side passages and the circular terrace at the garden room
Brickwork
Retaining wall, piers and coping that frame the patio
Team
Two Chiltern Surface Co technicians
Condition found
Established black spot lichen, green algae and soiling across the sandstone; failed jointing, with loose slabs on the semicircular back steps; displaced and freeze-thaw damaged coping bricks; algae across the brickwork
Work carried out
Controlled restoration cleaning, black spot treatment, the back steps lifted, relaid and fully repointed, the coping repointed, the retaining wall and piers soft washed, masonry protection cream to the brick edging, and Chiltern EverGuard™ applied to every treated surface
Outcome
The natural colour variation of the sandstone visible again, sound jointing on the steps, and the whole patio protected against regrowth
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Before · The day before the works
The Issues
Black Spot, Algae and Failing Joints
The Indian sandstone at this Princes Risborough home was carrying established black spot lichen, green algae and general soiling — across the rear patio, around the hot tub, on the steps and through the shaded side passages, where the growth was heaviest.
The jointing had worn or failed in places, and on the semicircular back steps three or four slabs had worked loose. Open joints let water into the bedding and give moss a foothold, so the steps needed rebuilding at the jointing, not patching.
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Before · Black with growth
The Issues · What We Found
Almost black, slab after slab.
Algae and black spot had taken the colour out of the stone entirely. In the shade, some slabs had gone close to black, with moss holding in every open joint.
Lichen, crusted in
Before · By the conservatory
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Lichen in every slab.
Before · Across the patio
Before · The garden room terrace
At the far end of the garden
The Garden Room Terrace
The circular terrace in front of the garden room was one of the worst-affected areas — pale lichen across every ring of stone, moss in the joints, the colour gone grey.
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Stage 01 · Restoration cleaning
Our Approach · Stage 01 of 05
01
Controlled Restoration Cleaning
Every area of sandstone was cleaned with commercial surface-cleaning equipment, at a pressure set for the stone rather than for speed — lifting the soiling, algae and loose organic matter without scarring the face of the slabs.
Garden furniture and planters were moved and returned, and the hot tub stayed in place, protected throughout the works.
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Stage 02 · Black spot treatment
Our Approach · Stage 02 of 05
02
Targeted Black Spot Treatment
Black spot is a lichen that roots itself into the pores of sandstone. Cleaning alone makes it look gone; left untreated, it comes straight back. A dedicated black spot treatment was applied across the clean stone and left to work.
Soft washing is letting the chemistry do the work. Knowing which treatment to use on which surface, and when, is what Chiltern Surface Co technicians are trained for.
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Before · Joints open, slabs loose
Our Approach · Stage 03 of 05
03
The Back Steps, Relaid and Repointed
Rather than patch the failed sections, both semicircular steps were rebuilt at the jointing. All of the old pointing to the treads and risers came out, every step slab was lifted and relaid on a fresh bed, and the whole step was repointed — including the joint where the step meets the house.
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Stage 04 · The brickwork
Our Approach · Stage 04 of 05
04
Retaining Wall, Piers and Coping
The brick retaining wall and piers that frame the patio carried the same algae as the stone — and would have re-seeded the clean paving within a season. The displaced coping bricks were ground out and repointed to secure them, then the brickwork was soft washed at very low pressure.
A breathable masonry protection cream went onto the bricks, reducing the water they absorb so there is less to freeze and blow the faces apart in winter.
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EXPERT CARE. LASTING RESULTS.
Our Approach · Stage 05 of 05
05
Chiltern EverGuard™ Protection
Surface cleaning is not enough. Black spot, algae and lichen live within the pores of the stone, not just on it — and whatever is left inside will grow back.
Chiltern EverGuard™ is a biocide that penetrates the pores of the material, kills the growth living inside the stone and inhibits regrowth. With the remedial works complete, it was applied to every treated surface — the sandstone and the brickwork alike.
It keeps working after it goes on: any remaining black spot dies back and weathers away over the following weeks, so the stone continues to improve after the team has left.
12–24
Months · typical Chiltern EverGuard™ protection, depending on the surface and its surroundings
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The Results · The Garden Room Terrace
Every Ring, Every Joint
Grey with lichen before the works, the circular terrace at the garden room was cleaned, treated and protected with Chiltern EverGuard™ as part of the same programme — so the whole garden now reads as one finished surface.
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The Results · The main patio
The Colour Back in the Stone
Under the black spot and algae was a warm Indian sandstone. Cleaned, treated and protected with Chiltern EverGuard™, its natural colour variation reads again from the lawn to the house.
By the conservatory
The back steps · Relaid and repointed
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The Results · Towards the conservatory
The Results
Warm again, end to end.
From the conservatory to the garden room, the sandstone has its colour back — and the brick edging, piers and coping that frame it are clean and protected with masonry cream.
Brick edging and coping
The Results · At the conservatory
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Before
After
Before and After · The same view
Chiltern Surface Co · Buckinghamshire
Sandstone Patio Cleaning in
Princes Risborough, Buckinghamshire
Chiltern Surface Co carried out this Indian sandstone patio cleaning in Princes Risborough, Buckinghamshire. We also offer patio cleaning, driveway cleaning, roof cleaning and roof moss removal across Oxfordshire and Berkshire, including Thame, Watlington, Windsor and Cookham.
Black spot lives in the pores of sandstone, not just on its surface, which is why a lasting result is a staged process — controlled cleaning, targeted treatment and protection with Chiltern EverGuard™ — rather than a single pass with a pressure washer.
Chiltern Surface Co · Princes Risborough, BuckinghamshireExpert Care. Lasting Results.
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Chiltern Surface Co
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