Pressure washing in Banstead

It depends almost entirely on drying time rather than on the clean itself. An open, sunny surface that dries quickly after rain stays clear far longer than one in permanent shade under a hedge or on a north elevation. Aspect, drainage and tree cover decide it, which is why two Banstead properties on the same street can need doing at quite different intervals.

Say so, ideally before the van leaves. That is the reason for walking the job at the end and showing you what has been done and what turned up along the way. If something has been missed or is not as expected, hearing it there is far better than hearing it a week later.

Most things, and the parts that will not are flagged before you commit. Deeply soaked oil, black spot lichen that has been in sandstone for years, tyre polishing on worn block paving and faded roof tiles all improve instead of disappearing, because the marking is in the material rather than on it. Setting that out beforehand is fairer than explaining it afterwards.

We do not make guarantees about how long a surface stays clean, because that depends on shade, drainage, tree cover and weather, none of which we control. What we do instead is tell you upfront what a realistic result looks like on your surface, what will and will not shift, and how quickly it is likely to need doing again.

On shaded, north-facing and permanently damp surfaces, yes, because a biocide kills the spores left behind instead of only removing what you can see, which slows the regrowth meaningfully. On open sunny areas that dry quickly it adds much less. Which category your property falls into gets established first, instead of applying it as standard.