Should you seal a patio after cleaning? It is the question we get asked most once the kit is packed away and the slabs are still dark and wet. The patio looks better than it has in years, and sealing feels like the obvious way to hold on to that. On plenty of jobs, we tell people to leave it.
There is no single right answer, because a sealer does one very specific thing: it changes how water moves through the surface. Whether that helps or hurts depends on the stone under your feet.
We do a fair bit of patio cleaning around Thirsk and the villages either side of it, and the patios tend to fall into two camps. One camp gets something real out of a sealer. The other camp is better off without one.
Should you seal a patio depends on what the stone is made of
Porous, open stone takes a sealer well. Indian sandstone, most concrete slabs and block paving all soak up water and staining, and an impregnating sealer slows that down. It will not stop a barbecue grease mark landing, but it buys you time to wipe one up before it sinks in. On a sandstone terrace that catches the afternoon sun, sealing usually earns its keep.
Dense surfaces are a different story. Slate, porcelain, granite and the tighter riven stones barely absorb anything to start with. A sealer on those sits on top rather than soaking in, and once it begins wearing off it goes patchy. You can end up with a patio that looks worse in year three than it would have done untouched.
Older patios laid straight onto soil or sand are the ones we are most careful with. If moisture is working its way up from below, a coating over the top gives it nowhere to go.
A sealer traps whatever is underneath it
This is the part the tin does not tell you. Sealing a damp patio, or one with algae spores still sitting in the pores, locks the problem in rather than out. Two summers later the green comes back from underneath the coating, and stripping a failed sealer is a slower and dearer job than the original clean ever was.
Timing matters as much as the product. A patio has to be properly dry before anything goes on, and after a wash in North Yorkshire that means several dry days, not one sunny afternoon. In practice that rules out most of autumn and winter here.
If you do go ahead, a matt impregnating sealer is a safer bet than a wet-look one. Wet-look finishes are the ones that go milky and peel at the edges, and they are also the ones that turn a patio into a skating rink in the rain.
What sensible paving aftercare looks like
For most of the patios we clean, the aftercare that actually keeps them right is simple and costs nothing. Brush the leaves off before they rot down into the joints. Keep the gutter above the patio clear so you are not washing grit across it every time it rains. Deal with the shaded corner early, because that is where the green always starts.
Looked after that way, a cleaned patio holds up well for two to three years before it wants another visit. A sealed one might stretch to four. Whether that extra year is worth the outlay is a fair question, and the answer is different for a sun-trap sandstone terrace than it is for a shaded slate one.
We would rather tell you it does not need doing yet than sell you a coating your patio cannot use. If you want eyes on yours, we cover Thirsk and the surrounding area for free quotes and the contact form is the quickest way to get one.