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How to Angle the Patio for Drainage

Aurora LaJambre

A new patio should be angled on a slight slope so water will run off of the surface and flow away from the house. Whether the patio is laid with pavers, flagstones or bricks, in order to angle the surface, you must first angle the foundation. This is a straightforward but laborious project that can take several days to finish, depending on the size of the patio.

Patios should have a slight angle so water runs toward a safe drainage outlet.

Step 1

Outline the sides of the patio by laying ropes on the ground. Measure the length and width with measuring tape and expand the borders as needed to fit your furniture and other items.

Step 2

Dig out grass and topsoil from within the outlined patio with a shovel and dump it on a tarp. Excavate about 8 inches of topsoil, and verify the depth in each area of the site with a measuring stick.

Step 3

Angle the subsoil away from the house. Stretch measuring tape from the side closest to the house and mark each foot of distance in the opposite direction. With a shovel, dig out another 1/4 inch of topsoil with every foot on a smooth, consistent slope. Once finished, the side of the patio farthest from the house will be 1 inch deeper than the section 4 feet closer to the house.

Step 4

Compact the sloped subsoil with a plate compactor or manual tamper.

Step 5

Shovel 5 inches of crushed rock into the site. Lay a board on top of the gravel and place a 4-foot level on top. Shift the rocks until 1/4 of the bubble sits outside of the center lines on the level. Compact the rock foundation.

Step 6

Fit metal or PVC edging against the inner perimeter over the gravel. Hammer 12-inch lawn spikes through the slots along the bottom.

Step 7

Cover the crushed rock with a 1-inch bed of grit sand, and smooth it by dragging a long board over the surface. Lay the board over the sand from the highest to lowest point of the base. Set the level on top and adjust the sand until 1/4 of the bubble sits off center.

Step 8

Place the patio pavers, stones or other material directly on top of the sand bed without dragging it. Begin at the center of the lowest side of the patio and work out to the ends. Butt each piece against adjacent ones following your chosen design, and hit them gently with a mallet so the surfaces align.

Step 9

Brush fine sand between the joints with a firm shop broom. Pack the sand down until the gaps are completely full.