Chepstow · Monmouthshire · Forest of Dean
Free quotes — 07947587517
Chepstow · Monmouthshire · Forest of Dean
Free quotes — 07947587517
The most common patio material in this part of Wales — and the one most commonly ruined by the wrong cleaning method.
Send a close-up of the black spot.
A wide shot tells us the size. The close-up tells us how established the lichen is, which is what actually moves the price.
Most sandstone patios are priced the same day.
Independently vetted and monitored
Trained in exterior cleaning chemistry
Never the same pressure on every stone
The price agreed is the price paid
Treat it first, then wash it gently. Indian sandstone is porous and soft, so the right approach is a treatment that kills the algae, moss and lichen at root level, followed by a low-pressure soft wash that lifts the dead growth without touching the stone itself. High pressure held close to sandstone tears the surface open, and that damage is permanent.
We clean Indian sandstone patios across Chepstow, Caldicot, Monmouth and the surrounding villages. Quotes are free and fixed before we start. Call 07947587517.
Why Indian sandstone goes green so quickly
Indian sandstone is porous. Water sits in the surface rather than running off it, and in a damp, sheltered, often north-facing garden — which describes a great many gardens around the Wye valley — that creates ideal conditions for algae, moss and lichen.
The open pore structure that makes sandstone pleasant underfoot is the same thing that keeps it damp for days after rain. Damp stone is what growth needs.
Patios go where the house shades them, backing onto planting and hedging. Almost every north-facing sandstone patio we see is greener than the same stone would be in the open.
Between October and March a shaded patio here rarely dries out at all. Growth that established in autumn simply carries on through to spring.
Those black spots are lichen, not dirt
The small dark circles that appear on Indian sandstone are lichen, and they are the hardest thing to remove from any patio surface. They are not sitting on top of the stone — they are rooted into it.
That is why scrubbing does nothing, why a jet wash takes the top off the stone before it takes the spot off, and why the spots come straight back after a DIY clean. Anyone who tells you black spot comes off in a single pass with a pressure washer has not dealt with much of it.
A treatment applied to the stone and given time to work on the lichen at root level. Time is the active ingredient as much as the product is, which is why this is a job that cannot be rushed and why a second application is sometimes needed on older stone.
We will tell you at the quote how much of it we realistically expect to shift, rather than promising you a clean slate and hoping.
Why you should not pressure wash sandstone hard
This is the single most useful thing we can tell you about your patio, and it costs us work to say it.
Sandstone is soft. A high-pressure lance held too close, or held in one place too long, tears the surface open. The damage is called pitting.
It cannot be repaired. And it makes the problem worse rather than better: a pitted surface is rougher, holds more water, and goes green faster than it did before. We regularly quote for patios that have been made worse by a previous clean.
A pressure washer will make sandstone look better for a fortnight. It will make it worse for the next ten years.
High-pressure jet wash
Treatment and soft wash
Result on the day
Dramatic, and often striped where the lance lingered
Even, and it keeps improving as treated lichen weathers off
Stone surface
Pitted, permanently
Left intact
Black spot
Surface only — the roots stay in the stone
Killed at root level
Mortar joints
Blown out on pointed patios
Undisturbed
How fast it regrows
Faster than before, on rougher stone
Slower, from a sound surface
How we clean Indian sandstone
01
Not all Indian sandstone is the same. Riven, sawn and older weathered stone behave differently, and a patio that has already been jet washed once needs handling with more care again. We test somewhere it will not show.
02
The treatment goes on and is left to work at root level rather than being rinsed straight off. On heavy black spot this is where the result is decided.
03
Low pressure, high volume, with the chemistry doing the work rather than the force of the water. This lifts the killed growth without touching the stone.
04
Sandstone patios here are usually mortar-pointed rather than sanded. We check for failed pointing and tell you honestly if it needs repointing. That is a separate job and a different trade, and we would rather you knew now than found out next winter.
What to expect afterwards
Most Indian sandstone is considerably warmer and more varied than it looks after a few years of algae. Cleaning reveals the original colour rather than bleaching it, and people are routinely surprised by how much buff and rust was under there.
Killed lichen does not always lift on the day. On some patios the last of it weathers off over the following weeks. We tell you which to expect for your stone before we start.
Nothing outdoors stays clean permanently, and a shaded patio in this climate greens faster than one in the open. Anyone quoting you a guaranteed number of years without qualifying it is guessing.
Should Indian sandstone be sealed?
It is a fair question, and the honest answer has two halves.
On the stone itself: sealing a porous material like Indian sandstone does slow algae regrowth, resist staining and deepen the colour. It is one of the few surfaces where sealing genuinely earns its keep. It also has to go onto stone that is completely clean and completely dry, which in this climate means a separate visit rather than the same afternoon.
See the difference
Drag the handle across. Every photograph on this site is our own work in the Chepstow area — we do not use stock images.
What it costs
Sandstone is priced like any patio clean, by the square metre. The variable that moves it is how established the lichen is: a patio with light surface algae is a straightforward job, and one with black spot rooted in over ten years needs more treatment and more time.
That is why the close-up photo matters more than the wide one. Send both and we can usually price it without visiting.
Including an honest assessment of how much of the black spot we expect to shift. If we think a second treatment will be needed, you will know that before you book rather than after.
We do not write testimonials on a page we control. These are pulled live from our Google Business Profile, where they are verified and where we cannot edit them.
Half the patios laid here in twenty years are this stone
Tutshill
Sedbury
Bulwark
Caerwent
Crick
Magor
Undy
Rogiet
Llangwm
Monmouth
Lydney
Bream
Woolaston
Alvington
Llandogo
Thornbury
Olveston
Severn Beach
Pilning
Common questions
Usually, but not always in a single visit. Black spot is lichen rooted into the stone rather than sitting on top of it, so it needs treatment and time rather than force.
Deeply established lichen on older stone can need a second treatment. We will tell you at the quote stage what we realistically expect to achieve.
It will reveal the original colour, which often surprises people. Most Indian sandstone is considerably warmer and more varied than it looks after a few years of algae.
It will not bleach or lighten sound stone. What you get back is what was laid.
You can, and it is the most common way these patios get damaged. High pressure held close to sandstone tears the surface open, and that pitting is permanent.
A hired pressure washer will make the patio look better for a fortnight and worse for the next ten years. If you are going to do it yourself, keep the pressure low and the lance moving and well back.
The products we use are applied at controlled dilutions and rinsed thoroughly. We cover nearby planting and ask that pets stay indoors during treatment and until the area is dry.
If you have a pond, tell us before we start. That genuinely changes how we work and is easier to plan for than to work around on the day.
It is priced by the area, like any patio clean, with more allowed where heavy black spot needs extra treatment or a second application.
Send a photo of the whole patio and a close-up of the worst area and we will give you a fixed price. See what changes the price.
Sealing does genuinely help on a porous stone like Indian sandstone: it slows algae regrowth, resists staining and deepens the colour. It has to go onto stone that is completely clean and completely dry, which usually means a separate visit.
This page does not sell a service until that is confirmed.
Shaded, north-facing and tree-covered sandstone patios in this area generally need annual attention. A sunny, well-drained one can go longer.
The Wye valley is wetter than most of England and it shows on porous stone more than on anything else.
Nothing costs more because of where you are in town. What changes is what the property needs.
All five patio surfaces we work on.
Patios and driveways, and the joints afterwards.
Often done on the same visit as the patio.
The same low-pressure principle, on walls.
An overflowing gutter is what stains the patio below.
What moves the number on every service we offer.
Get a free quote for your sandstone patio
Send a wide shot and a close-up of the worst black spot. We will tell you honestly what we expect to achieve and give you a fixed price, usually the same day.
Or speak to the person who will do the work:
