Concrete garage floors in London
Garage floor work in London splits between two quite different situations, and the first one is as much a logistics problem as a concrete one.
On the century streets the garage is detached and sits at the back of the lot, reached by a long narrow driveway or a laneway. Those slabs are frequently very old, poured thin and on almost no base at all, and on clay that combination cracks and settles until the floor is a patchwork. Replacement is usually the honest answer, and replacement means rebuilding what is underneath rather than skimming what shows.
The complication is access. A concrete truck often cannot get to the back of one of these lots, so the pour needs a pump, a buggy, or staging, and that changes the price. It is exactly the sort of thing that should be established at the site visit rather than discovered on the morning of the pour, and we walk the access route before quoting.
In the north end the garages are attached doubles and the work is standard. Pitch toward the door, set at the pour, so the meltwater and road salt that arrive on the cars actually leave rather than sitting on the slab and against the base of the wall. Salt in solution is much harder on concrete than salt lying dry outside, and a flat floor holds it for hours at a time. Pitch cannot be retrofitted in any satisfying way: a topping over a flat slab eats headroom and rarely drains properly.
Joint layout follows the size and shape of the bay so the concrete cracks along planned lines rather than diagonally across the parking area, and thickness follows use: four inches over a compacted base for cars, six where a hoist or a workshop is in the plan.
Coatings suit a sound, dry slab and make winter mess far easier to handle. They need moisture testing first, because a coating over concrete still pushing vapour will lift from below whatever was done to the surface.
Replacing a floor inside an existing garage generally is not permit work. Structural work to the building itself is, under By-law B-7.
The frost wall carrying a detached garage has the same 1.2 metre depth requirement as any other foundation in the city, and on this ground that depth is doing real work rather than satisfying a rule. Low-permeability silt and clay holds water against the footing all winter, and saturated silt is highly frost-susceptible, so a garage founded shallow moves and takes its slab with it. Where a floor is being replaced inside an existing structure, that is also the moment to find out how the existing walls were founded, because a new slab poured against a foundation that is still moving inherits the movement.
We also pour the driveways that reach these garages and the walkways beside them, and cover the rest of our London service area.
East along the 401 the housing mix and access conditions differ, covered on concrete garage floors in Cambridge. Further east the garages are largely attached postwar, dealt with on garage floor concrete in Kitchener.
