How to Pour & Finish Concrete Inside a Building

Remove any flooring that already lies where you intend to pour the concrete. Don't pour concrete over wood or any other type of weight-restrictive flooring. Instead, you must return the flooring areas to ground level.

Clean the surface of the ground inside the building where you'll pour the concrete. Remove any objects in the way, including pieces of flooring that you may have removed, and level the ground as much as possible, using a visual assessment to determine when the ground sits level. Pour granular fill over the leveled ground, leveling the fill as much as possible as well, and use a tamper to press the granular fill down tightly.

Build a wood form on the ground’s surface that sits as tall as you would like to make the concrete floor slab inside the room in which you intend to pour the slab. The concrete floor should sit at least 4 inches deep, though you can make the floor deeper if necessary to sit level with the bottoms of the walls. You can also pour the concrete directly into the concrete foundation walls if that suits your purpose.

Get a building permit from your local government’s housing department before attempting to pour the concrete walls. Use the information provided with the building permit to lay reinforcing steel ("rebar") into the flooring area inside the frame where you want to pour the concrete floor. Different areas require different placement of rebar to be within code.

Rent a concrete truck to mix concrete and to keep concrete mixed during the pouring process. Park the truck as close as possible to the area of the building where you'll pour the concrete, and use wheelbarrows to haul the concrete from the truck to the floor, dumping the concrete into the prepared form until the form has been filled to its edges.

Drag a screed over the concrete surface to level off the concrete as it is added to the form. Pull up the rebar or mesh inside the form as the concrete is poured, bringing the rebar pieces up to the level required by local government regulations, using a metal hook.

Allow the concrete to set up for a few hours, then use several steel trowels, attached to poles if necessary, to level the concrete off to a smooth, finished indoor surface. Drag a push broom over the surface to add some texture, which will help prevent slipping on the floor’s surface.

Spray a chemical curing agent on the floor’s surface once you finish texturing the floor. Stay off the concrete floor for at least four days.