Can You Pour New Concrete Floors Over Old Concrete

You can level an existing concrete floor with a leveling layer of new concrete but you must prepare the old concrete floor first.

Can you pour new concrete floors over old concrete. There are cases when pouring new concrete over old just isn t a viable solution. When it comes to curing wet hessian is to be placed on top of the concrete not too early though wait till you can get a steel float finish on it. For this to be feasible the contractor needs to pour at least 2 inches thick use smaller aggregate and incorporate reinforcement such as welded wire mesh or fiber mixed into the concrete. We d say no since concrete doesn t have any bonding agents of its own to grip onto the new layer but it s a yes if you get a layer in between the two and help the top layer adhere to the surface beneath.

Oil dirt and other debris can affect how the new concrete bonds with the old. The condition of the existing slab is the primary factor that determines how long the new concrete will last. I suggest a minimum of 2 thick so you have to be able to accommodate the new slab height whether it s a floor patio driveway or walkway. Pouring concrete over old concrete instead of directly over a new gravel foundation limits your ability to maximize the slab s lifespan.

In maine where i ve been working with concrete for 40 years now and this website is where i can share with you all the knowledge and wisdom i ve gained from installing all kinds of decorative concrete concrete floors concrete overlays stained concrete and also fixing cracked or spalled concrete. If done properly new concrete can often be poured right over an existing slab. If you re concrete has large cracks and the slab may still be moving due to freeze and thaw conditions or settling then a tear out and replace is a better solution. Before pouring concrete over existing concrete driveway or sidewalk surfaces remove stains and loose material so the new concrete can stick properly.

So you may ask if pouring new concrete over the old one is a better option. A well poured concrete slab with a deep sturdy foundation can last for 30 to 40 years. They will consider the existing slab structurally sound and just pour the new slab as if they were pouring over a gravel base. Neglecting to prepare the old surface will prevent the new concrete from adhering correctly resulting in a weak bond between the two layers.

If it s a solid piece of concrete maybe some minor cracks and the surface is worn ugly or pitted you can pour new concrete right over it. However most contractor will simply come out and place a rebar mesh on small pedestals above the existing floor and then pour enough concrete to level the area and cover the rebar mesh.