Top-Rated Why the Sand Washes Out of Paver Joints

Joint sand does more than fill a gap. It is what locks the pavers against each other so the surface behaves like one unit instead of a few hundred loose stones. When it goes, the pavers start to shift, edges roll, and weeds and moss move into the space. So it is worth understanding why it leaves.

Rain volume is the main cause. We get a lot of slow, sustained water. Plain sand is not bonded to anything, and over a few winters it simply migrates out of the joints and down the slope. This is normal and it happens to every patio eventually.

Downspouts make it much faster. If a downspout dumps onto or near a paver surface, that one spot will lose joint sand far quicker than the rest of the patio. If you see a fan-shaped area where the joints are empty and the rest looks fine, follow the water uphill and you will usually find a downspout. Fixing the discharge is worth more than any amount of re-sanding.

Pressure washing done wrong strips it out. This is the one I see most, and it is usually self-inflicted with a rented machine. A narrow wand tip held close will blast joint sand out in seconds. It also etches the paver face. Flat surfaces should be cleaned with a surface cleaner, which spreads the pressure evenly and is far less aggressive on the joints.

What re-sanding actually fixes. After cleaning, I sweep polymeric sand into the joints and set it with a light water activation. Polymeric sand contains a binder, so once it cures it holds together instead of washing out with the next storm. It resists weeds and moss for the same reason, since there is no loose material for them to root into.

The part people skip is that re-sanding only works on clean, dry joints. New sand over old compacted sand and moss does not bond and will fail. That is why cleaning and re-sanding are one job rather than two.

Signs you are due: joints that sit noticeably below the paver surface, pavers that rock slightly underfoot, weeds coming up in lines rather than randomly, and sand fanned out across the bottom edge of the patio after a heavy rain.

If your patio is at that point, I can clean and re-sand it in the same visit. Quotes are free.