A patio can be a wonderful addition to any home. It provides a relaxing spot for friends and family to gather, and it allows you to spend more quality time outdoors.
However, it is important that a patio have the proper slope when it is constructed. Rainy days will almost certainly bring water to your patio, and if it is not sloped properly, you can end up with standing water that attracts mosquitoes or even worse, water that moves toward your home and its foundation.
So, how much slope should a patio have?
Generally, a patio slope should drop 1/4 of an inch vertically for every horizontal foot. While steeper slopes are fine (although sometimes inconvenient), a more gentle slope can cause pooling and even direct water back toward your structure. This can eventually cause water damage and even foundation problems.
I already touched on this subject when I explored “how to build a patio on a slope“. However, that was more focused on dealing with an existing slope. I’m talking about how much slope the actual concrete should have!
In any case, I wasn’t satisfied with the answer there, so let’s really explore what the correct slope should be.
Correct Slope for a Patio
As I said above, you can have a steeper slope, but if you have anything less, you will take a chance that the water will run back toward your home.
When you want to measure the patio length, start at the side that touches your house. Measure in feet away from your house to the furthest point of the patio. Take this measurement and multiply it by ¼ to determine how many inches the difference in elevation should be between each end of the patio.
For example, if the patio is 20 feet in length, the slope should be five inches. This means that the side furthest from your house will be five inches lower than your house.
This is a two percent drop, and it is the ideal slope for a patio to effectively drain away from your home.
Fixing A Patio With An Improper Slope
If your patio has a problem with standing water, it’s possible you may have an improper slope.
Don’t worry just yet, several solutions are available to fix your problem. However, don’t get your hopes up! It’s very possible the only “fix” is to demolish the existing setup and start over. It boils down to how flat your current patio is.
In a perfect world, your patio would have been constructed with ¼ inch of slope per foot of length. If this is not the case, it can cause terrible problems and possibly damage the foundation of your house.
One way to correct this problem is by adding a drain.
The drain should be placed close to where the standing water is collecting. You can mark this location and use a jackhammer to dig up the pavement. Once the concrete is removed, you will dig a trench until it can hold a two-inch layer of sand and the drain channel.
The sand should be sloped away from the house at the rate of one inch per 20 feet. Once you lay the drain channel in the sand, you can cover the drain with a gate.
Although you can add a drain to an improperly sloped patio, the best way to handle this is to make sure that the patio is sloped correctly when it is built. If you have a concrete pad for your patio, you can actually fix it.
If there are no cracks in the concrete slab, you can pour concrete right over it and slope it properly. However, if you have pavers or stamped concrete, you might have a more difficult time.
Starting Over
When you are building a patio from scratch, you will have no trouble making sure that it is sloped correctly. The recommended slope is 1/4 inch per foot, but it can be anywhere from 1/8 inch to 3/8 inch per foot depending on other factors.
You need to remove any vegetation, soft soil, and rocks before you begin. The patio needs to have a uniform surface to lay on. You can run a pipe under the patio to help with draining, or you can install a French drain at the edge of the patio.
It is a good idea to look at your property and see what the natural tendency of the water flow is.
If the land is sloped up from the spot where you want to put the patio, you are going to have a more difficult time sloping the patio to drain away from your home. You might need to consider a more sophisticated drain system.
Once you make sure that the ground is uniform in materials and level, you are ready to lay your patio. You can have a concrete slab poured, or you can be creative and use stone or pavers.
Whatever you choose, the slope is critical, and this will ensure that water flows away from your house.