How to clean a garage floor, bare concrete or tiles

Start with what is actually on the floor

A garage floor collects a specific set of things and they want different treatment. There is the fine grey dust that comes off unsealed concrete itself, and gets everywhere. There is grit and road dirt from the car. There is oil, either a fresh spill or a stain from before your time. In winter there is salt-laden water off the wheel arches that dries to a white crust. And there are leaves and the mush they become when they get wet under the door. Most people reach for the hose and make all of it worse.

The order is always the same: dry first, then wet. Sweep before you wash, because a hose on a floor covered in dust and grit makes a slurry that dries as a film and looks worse than the dust did. Deal with oil before water, because water spreads oil. Everything after that is easy. A garage floor cleaned in the right order takes half an hour; one cleaned with a hose first takes the afternoon and looks worse at the end of it.

Bare concrete: the dust is the concrete

The dust on an unsealed garage floor is not dirt that has landed on it; it is the surface of the slab wearing away, and it comes back after every sweep for as long as the slab is bare. A stiff broom gets most of it, a vacuum with a proper filter gets more, and a hose gets it wet, at which point it becomes a paste. Sweep dry, and accept that some comes back. That is the honest reason a floor covering of any sort makes a garage a nicer place to be: it stops the floor from being the thing you are cleaning up.

For a proper wash, sweep, then a bucket of warm water with a floor cleaner and a stiff brush, working from the back of the garage towards the door so the dirty water runs out rather than in. Squeegee it out of the door. Do not flood the floor: a slab with no membrane under it takes water in and gives it back for days.

Oil, grease and the stain that is already there

A fresh spill wants an absorbent before it wants anything else. Cat litter, sawdust or a proprietary absorbent, spread thickly, left for a while and swept up, takes most of the oil with it. Then a degreaser and a stiff brush on what is left, then rinse. Skip the absorbent and go straight to a wet degreaser and you have turned a puddle into a slick that runs to the low point of the floor.

An old stain that has soaked into the concrete is a different thing. Repeated degreasing lightens it but rarely removes it, because the oil is in the pores of the slab and not on the surface. If the floor is going to be tiled, an old stain does not matter at all; nothing bonds to it and nobody sees it. If the floor is staying bare, learn to live with the shadow.

Cleaning interlocking tiles

Tiles turn floor cleaning from a fight with the slab into an ordinary floor. Sweep, then a mop or a hose, then let it dry. A rigid polypropylene tile with an anti-slip surface has texture that holds a little dirt, so a stiff brush earns its place, but the tile itself is not absorbing anything and a spill wipes rather than soaks. Solvents and harsh cleaners are worth checking against the maker's guidance for the tile you have; a mild floor cleaner suits most.

Two things happen under the tiles that do not happen on bare concrete. Grit falls through the joints and collects on the slab, where it does no harm until there is enough of it to lift a tile slightly and make it rock. And water that goes through the joints stays there longer than water on an open slab, because the tile is stopping it evaporating. Neither is a reason to avoid tiles. Both are a reason to lift a row occasionally, sweep the slab under it, and let it dry before it goes back.

A pressure washer is where people go wrong. It blasts the dirt off the tile surface and forces dirty water through every joint at the same time, so the top looks clean and the slab underneath is wetter and grittier than before. A hose on a normal spray and a broom does the same job without pushing the mess downstairs.

Winter: salt, grit and where it goes

A car in winter brings in salt-laden water every time it comes home, and when the water evaporates the salt stays. On bare concrete it dries to a white crust that looks like the damp bloom and is not. On tiles it dries on the surface, or under solid tiles it dries on the slab where you cannot see it. Salt water sitting in either place all winter is worth getting rid of, and the answer is a hose and a squeegee rather than a broom, which just moves it about.

The door is where all of it lands, so the row of tiles inside the door is the one to lift and look under when the weather turns in spring. It will have the grit, the salt and the leaf mush of a whole season under it. Ten minutes with a broom and it goes back, and the rest of the floor never needed touching.

A floor you can reach is a floor you clean

The reason most garage floors are never cleaned is not laziness; it is that you cannot get to them. A broom does not fit between the mower and the bikes, so the floor under them is where the dust and the damp accumulate for years. Every long thing that leans in a corner and every box that sits on the floor is a patch of slab nobody will ever sweep.

Put the long things on wall hooks, hang the bike, and get the boxes onto shelving. That is not about tidiness. It is about the broom reaching the whole floor in one pass, which is the point at which sweeping the garage becomes a five-minute job rather than a weekend one, and therefore something that actually happens. The floor under a hung bike gets swept; the floor under a leaning one never does.