When should I install a floor safe — while pouring the concrete deck, or after?

When a new concrete deck or slab is being poured, we generally do not recommend setting the floor safe into it at the same time. Casting the safe in with the deck makes it hard to keep level, the safe can shift or float in the wet concrete, and any mistake is very difficult to correct once it has set.

Also, the humidity from the concrete deck could lead to corrosion or damage the code lock, especially if there is no a roof covering the concrete deck when constructing a new house.

Instead, reserve the opening with a block-out. Before the deck is poured, place a polystyrene insulation panel where the safe will sit, sized so there is at least 100 mm of clearance on every side of the safe (and at the base). Pour and finish the concrete deck around the polystyrene.

Once the deck has fully hardened, remove the polystyrene to reveal the recess. Lower the floor safe into the opening, level it with a spirit level, and pour the concrete mix around it so the body is encased in at least 100 mm of concrete on all sides.

This sequence keeps the safe clean and protected during the main slab pour, lets you confirm the safe opens, closes and locks before final casting, and gives a correctly aligned, fully encased installation. Keeping the safe surrounded by at least 100 mm of concrete is also what maintains its EN 1143-1 rating and your insurance cover.