Effective Patio Drainage for Paver Patios
Although it may not be the first thing on your mind when you plan your new paver patio, drainage will greatly impact your ability to enjoy your new living area. Drainage is the natural or artificial movement of surface or sub-surface water, and without a proper setup, water can roll back on your foundation, causing erosion. Standing water can breed insects and ruin landscaping, and it can also cause a paver patio to subside, throwing the entire area out of level. There are a number of ways you can effectively drain the water from your patio.
The base of your patio provides drainage. Unless you have mortared each paver, there is a certain amount of sand in between each piece. Water will percolate through this sand until it reaches the base. Depending on whether you properly laid a base of gravel or sand, the water may pool under your pavers, or it may wash out the sand if not properly compacted. This will cause your pavers to sink. Therefore, your first line of defense is to properly lay the base when installing the patio.
One of the simplest ways to drain water away is to slope the base of your patio. The natural pull of gravity will drain water down the slight slope you have created. To effectively move the water, you will need to grade the base 1/4-inch for each linear foot of your patio surface.
Some soils hold water, but other soils drain quickly. If water will stand, consider installing a patio drain that ties in to a drain pipe. Run the pipe under the pavers and out to an area that will handle the outflow. Do not drain your water directly into a storm drain or ditch as this water can be full of contaminants that will end up directly in your local streams and lakes.
Even if you move it off the patio and away from the house, you may still have to move the water elsewhere. You can install a French drain at the edge of the patio (downslope) to do this. Make your own from a PVC pipe with holes in the bottom, buried under gravel that allows water to sink to the pipe once it hits. The French drain then carries the water to where you want it.
You can also construct a drywell to handle excess water. This is a hole or barrel filled with gravel and sand that transfers water into the subsoil by holding it until it can percolate naturally. A drywell is a good choice to receive the water from a French drain, or could be put in under your patio as part of the base. This is only recommended if you know it can handle the water flow, or if you can not move the water to another area of your yard.
If you have already installed your patio, and it turns into a pond with each rain, you should likely bite the bullet and start over. Take notes about the water flow in the area, noting problem zones, and re-plan your patio utilizing multiple tools to move water safely and effectively.