How to Lay New Sod Over Existing Sod

Spray the existing sod with a fast-acting glyphosate-based herbicide. Check the label to ensure that reseeding or sodding can occur quickly after application. Wait for the allotted time before continuing.

Mow the yard using the shortest height setting on the lawn mower. Rake up any clippings and remove all large debris, such as rocks or sticks, from the yard.

Work the area with a steel rake to remove any accumulated thatch. Score the top 1/4-inch of soil as you rake. Level out any bumps or mounds of soil, and add that soil to any holes in the yard.

Apply an even layer of a starter fertilizer with a 1-2-1 or 3-4-1 ratio to the top of the existing sod at a rate of one pound of nitrogen for every 1,000 square feet of yard. Rake the fertilizer into the soil and sod.

Lay the new sod normally. Keep the sod moist as you work, and lay it in a brick-like pattern, with the end seams of the sod panels in one row aligning with the centers of the panels in the surrounding rows. Cut the sod as necessary to fit irregular areas or borders. Push the seams of the sod panels flush against the seams of the surrounding panels.

Smooth out the new sod with a lawn roller after installation.

Add one inch of water to the soil. Stick your finger into the soil to check that the root layer of the sod is moistened. Water the new sod every day or two -- just enough to keep the root layer moistened -- until the grass takes root in the soil and old sod underneath, then switch to watering the lawn once or twice a week as needed.