Patio and driveway paving
The most-asked outdoor cleaning question in this register, and the manufacturer's own guidance spends more words on how NOT to pressure wash it than on how to clean it.
Precautions
- Wear gloves
- Wear eye protection
- Test on an inconspicuous area first
- Dispose of responsibly
In detail
Almost everyone asking about a patio is asking one of two things: why it keeps going green, and whether the pressure washer will wreck it. The green is algae, moss or lichen, and where it grows is the diagnosis rather than the problem. The paving manufacturer names heavy shade, overhanging trees, and paving not laid to an adequate fall. That makes it a drainage and light question, which is why it returns after every clean. On the pressure washer the answer is a qualified yes with a geometry attached. Used to excess it shortens the paving's service life. The lance is never aimed straight down, because that lifts the jointing material out from between the units; it is held at no more than THIRTY DEGREES across the diagonal; and the joints are inspected and refilled afterwards, because empty joints are bad for the pavement itself. The routine the manufacturer leads with is the one most people skip: regular brushing, and an acid-free soapy wash where the colour has been masked, rinsed until all the soap has gone. Run-off matters outdoors in a way it does not indoors: hypochlorite will burn or kill plants, so borders are protected and the wash water goes to a drain.
Related
- Patio and driveway paving is made from Concrete and stone paving
Sources for this page
Sources
Cleaning & Maintenance Guidelines — Gardens & Driveways
Marshalls plc · Manufacturer documentation
Relied on for: That organic growth is prevalent in heavy shade, under trees or where paving is not laid to an adequate fall, that the power lance is held at no more than thirty degrees across the diagonal and never directed down because that loses jointing material, that joints are refilled after washing, and that sodium hypochlorite will burn or kill plants. (states this directly)
Verification: a person has read the passage relied on.
Read on — General Advice, Power Washing, Acid Washing, Seasonal Maintenance, Sealants, the per-stain sections and Organic Growth. Supports the claim as stated.
Last reviewed by a person on .