Adding a patio to your home increases your living space to take advantage of the outdoors. Your patio can be rectangular or square, circular or a free-flowing design of your own creativity; building your patio can be as quick as a weekend DIY project or you can hire professionals to design and build your dream patio with features such as intricate paving patterns, flower beds and barbecues. No matter your patio’s design, it needs to have the correct amount of slope away from your house and its foundation or you’ll need to dig it up – and we will tell you why the proper amount of slope is the most important aspect of your patio and how best to achieve that.
The ratio for the right amount of slope on your patio to effectively drain water away from your house and its foundation is a 2 percent drop. This is the industry standard when building patios: the recommended slope is ¼ inch per foot of patio length. A patio’s slope can be greater in degree, but not less than this minimum.
To create, design and build a patio you liked that you spotted in a magazine, from a TV show or the Internet may look like a straightforward DIY job. However, your patio’s construction needs to still adhere to safe-building practices to avoid damaging your house and its foundations. A patio must have a slope. If it rains and the water collects in places, it will attract mosquitoes to breed and make your patio an unpleasant place to be. Another factor is that if water moves toward the house and its foundations, it could soften the surrounding ground and cause that foundation to crack. That could have costly and dangerous consequences.
Apart from water run-off damaging houses’ foundations, the construction of patios washes away the topsoil and can expose plants roots and create cracks in the concrete surfaces. The way water flows around your house must be carefully controlled.
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How Much Should a Patio Slope Away from a House?
As we have already established, the ratio for the proper amount of slope on your patio is a 2 percent or a ¼ inch per foot of patio length. A steeper slope is allowed, but don’t create a patio with a slope less than this ratio or your patio will collect water.
To calculate the right amount of slope for your patio, you must first measure the length of the patio from the side of your house that the patio meets to the furthest point that the patio area extends. Using the measurement, the next step is to calculate the elevation difference between each end of the patio and that be can determined by multiplying the length by 0.25 (¼ inch). The result is the number in inches of the elevation difference between each end the patio for the best water run-off.
Does your Patio Collect Water?
If your patio has an unsuitable slope, don’t become too stressed about it. It can be fixed in two ways and both can be undertaken by you as a DIY project. If you’ve moved into a new home with patio and realized that the water collects on the patio, or if you’ve built your patio and seen that your measurements weren’t correct, don’t fret.
As we know, standing water attracts mosquitoes. That water run-off to your house and foundation is a problem and the sooner that can be remedied the better. The extent to what your repair job will take depends on how flat your patio is and what sort of construction and base your patio is built on.
Your patio slope can be greater than ¼ inch per foot of patio length, but not less. The two ways to fix your patio collecting water are:
1) adding a drain
2) re-laying the patio if it is based on a concrete foundation
1. Adding a Drain to Your Patio
Once you’ve seen where the water collects after rainfall, or after washing down the patio to keep it clean of debris, and you’ve figured out where the problem areas are, you have a better idea of what needs to be done and how to achieve it. If your patio is created with paving or pavers – and has no concrete sub-base or foundation – your DIY repair job will be easier. Simply dig up the paving to clear the area. You’ll need to dig a trench of a least 2 inches deep and a slope of more than 3/8th of an inch per foot of length of your patio area affected to create a drainage channel. It is recommended to concrete the drain channel to reinforce it and prevent excess water draining into the soil and softening the soil too much. Add a drain gate to round off the drain channel.
2. Re-laying the Concrete Base of Your Patio
As with adding a drain, determine where the water collects to identify the problem areas. As you can’t simply dig up the paving, you will need to use more elbow grease to fix this slope. Once you have removed the paving or tiling, to uncover the concrete base of your patio, you need to examine it for any cracks on the concrete. You will need to pour more concrete over it to create the right amount of slope. This means you will need to add more concrete at the side that meets your house and shape it until it either has a slope of ¼ in per foot of patio length or greater. This is a time-consuming task and will require a lot of effort, but getting it right now will most certainly save you thousands of dollars in years to come in damaged house foundation repairs.
3. Make Sure Your Patio’s Slope is Correct
The recommended slope is ¼ inch per foot of patio length or a ratio of 2 percent slope of your patio’s length. There can be some variance to this by increasing the degree of the slope, but not in decreasing the slope.
The best way to undertake this is to carefully build a solid and level base to work from. You can start by removing all vegetation, grass, stones, and soft soil from the area you wish to build your patio on. It is recommended to tamper the soil to compact it to further increase its strength as a platform for your patio and while doing so you can examine where you’d like to place a drainage pipe under the patio. Find the area that the water collects at and which looks the dampest, and create a drainage channel in the soil. You can lay a pipe from that wettest area outwards from the patio and away from your house and its foundation.
Once the patio area is flat and level, and your pipe has been laid, you can then slope the surface according to the direction that the water flows away from your house and its foundation.
When you’ve achieved the slope ratio of 2 percent or 1/4in per foot of patio length, you can then lay your pavers or paving over the sloped surface to create your perfect patio.
Building a patio isn’t as straightforward as laying paving into shape and placing your garden furniture on top. The proper slope of your patio will not only prevent water from collecting on your paving and concreted surface but will also keep water running away from your house and your foundations. Getting the right amount of slope might seem tricky, but sticking to the calculation and ratio of ¼ inch per foot of patio length of 2 percent drop will ensure your patio will be a pleasure to use and an asset to your home’s future structural integrity.
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