How to Change the Slope on a Cement Porch

Determine the slope of the slab and how you want that slope changed. This will affect the method you use to fix it. If you want to level it out, determine how many inches of concrete to add or remove.

Use a concrete surface grinder to level any high spots, if necessary. Keep in mind that there are alternative options that would allow you to skip this step. A quick pour of concrete to fill low spots may be adequate for your needs. If there are large areas of sunken concrete, you can use a slab jacker to raise them and level out the overall surface, making a grinder unnecessary.

Use a slab jacker to raise areas of sunken concrete, if necessary. This tool works by drilling under a slab and injecting concrete into the voids where it has sunk. Let rest for a day before attempting additional fixes.

Prepare the concrete porch by cleaning it to improve the adhesive ability of subsequent layers of concrete. Sweep away any dust and apply chemical concrete cleaners, such as phosphoric acid, to clean and etch the surface.

Prepare the concrete mix according to manufacturer instructions if you need to raise areas of the porch more than 1/2 inch. If less than 1/2 inch of rise is needed, use only leveling compound. Pour the concrete mix to at least 1/2 inch below the desired level. Leave it rough and do not smooth or trowel until the second pour, as this improves adhesion. Let set for a few hours.

Prepare leveling compound according to manufacturer instructions to apply as the second pour. If you only need to raise the slope by 1/2 inch, use the leveling compound on its own without the concrete mix.

Pour the leveling compound and use a squeegee or broom to spread. Cover the entire area of the concrete porch to create a level surface. The compound works by filling sunken areas.