Just imagine the scenario – you’re expecting some friends round for a big BBQ at the weekend, but you’re hit by some wet weather at the last minute. As your patio doesn’t have a drainage system, rather than running away leaving a clear surface for your party – the water pools around your seating area and table, meaning your guests will get wet feet.
There’s nothing else to do but get the broom out to try and sweep away the water before they arrive. You know this could be avoided, so how do you keep your patio from flooding in future?
Both new and old patios can be fitted or retrofitted with many drainage options to stop them flooding. These include installing a pop up drain, building a French drain, adding gravel between pavers and regrading your patio so it drains away from your house.
Let’s dive down into this subject in more detail, and look at why you definitely need patio drainage – and what some of your best options are.
Do You Need Drainage For a Patio?
As we head into spring (hooray!), we need to be prepared for crazy spring weather. We need spring moisture, except for – foundations and patios.
The good news is water drainage is a straightforward thing. Water flows downhill. Water will always find the path of least resistance – to flow downhill.
Patios are large, flat areas that naturally collect water. They are often made of an impermeable material, like concrete. After hard, fast rains, water can stand on the patio. Pooled water attracts insects and can stain concrete. Moss, mildew and weeds all love moist places.
Patios sometimes act as great water conduits. Hard rains collected by your patio can be channeled right to your foundation. That’s because our patios are usually right up against our houses. Patios that may have once sloped away from your house might not have stayed that way through the years.
Patios that flood can result in damage to your home’s foundations, increase damp places for insects to breed and will eventually erode your lovely patio. Patios made with pavers are very susceptible to having areas of sunken pavers, creating unsightly tripping hazards.
Whether your patio is made from poured concrete, wood, or pavers, you need to keep water from pooling on it or running across it.
Here are some simple ways to improve patio drainage.
7 Ways To Improve Your Patio Drainage
Check For a Clogged Existing Patio Drain
This one is easy. Did you patio drain in the past, but now is a mini-swimming pool? Chances are that your drains are clogged.
Yup, drains need maintenance just like gutters. If you can, remove the drain covers, get your heavy gloves on, and pull out the gunk. When you have a clear path into the drain, try pushing your garden hose into the drain to wash out the rest of the leafy junk.
If that doesn’t work, you may need to enlist professional help. If you are a DIY person, check out snake-style drain cleaners at your hardware rental shop. Or some rentals offer hydro jetting machines.
Another DIY solution is purchasing a blow bag. A blow bag is a perforated bag that screws onto the end of a garden hose. You screw the bag onto the hose, push it as far as you can, then turn on the water. Water shoots out the perforations – hard – and hopefully dislodges the leaves or dissolves the mud.
Chemical drain cleaners are not recommended for outside drains.
Build a French Drain
If you enjoy a good mud bath and trenching through your yard sounds like fun, then a French drain DIY project may be for you. If it really doesn’t – you can call an expert.
First, let’s talk about porosity and permeability. Porosity is the amount of holes – or pores – something has. Permeability is the amount of pathways that connect the pores. Something can have lots and lots of holes, but if the holes don’t connect, water can’t run through it.
Gravel has porosity and lots and lots of permeability. As compared to garden soil, gravel practically sucks up water. That’s why French drains, soakaways, and permeable patios all use gravel.
French drains are perforated PVC pipe laid in a sloped trench full of gravel. The slope runs away from your patio and your foundation. The idea is to create a super permeable place – the gravel – for water to soak down into.
The PVC pipe has rather large holes every few inches. The pipe sits in the bottom of the gravel filled trench. The two rows of holes are positioned at the bottom of the pipe. Water runs into the gravel, fills up the bottom of the trench, then percolates through the holes in the pipe.
Water fills up the pipe. The pipe, because it is sloping, carries water away from your patio and out a drain. Here’s a good how-to website.
For a patio, you may need a French drain around the perimeter (you can fit PVC pipes together). Consider filling it in a dry steam bed style with gravel and larger rocks.
Build a Soakaway
Soakaways are big holes filled with gravel. Soakaways can be located in problem areas, or they can go with French drains. Soakaways don’t have to be round holes – you can make a soakaway hole at the bottom of your patio so that water runs off the patio and into the soakaway.
Soakaways work because they are large holes filled with very permeable gravel. Lots of water can be stored in the spaces between the gravel. Thanks to gravel’s permeability, the water then drains into your garden soil. Here’s a website.
Soakaways work well with a French drain system or an underground downspout. The drains are laid out to draw water away from problem areas, like the patio. Soakaways are located at the end of the drains, which are located some distance from the patio.
A word of caution – if you have clayey soil, soakaways may not work.
Add Gravel To Your Patio
If you have a paver patio, you can improve the permeability with gravel between pavers. This method is easiest if you are still in the design phase, but you still have options if you don’t.
If you already have a paver patio, you may be able to replace the existing sand with larger gravel. Take out a row around the perimeter, then move the pavers farther apart. Finish with gravel in between.
Cement pavers and flagstone set apart and filled with colorful gravel or pebbles are striking. If your patio is a cement slab, you can cut a pattern of channels into the patio and then fill them with gravel.
Regrade Your Patio
Regrading your patio is not an easy solution. Basically, you need to change the slope of your patio to run away from your house.
If you have a paver patio, then you can remove rows nearest the house, add gravel underneath, replace the pavers and fill the gaps with more gravel.
For a solid slab patio, mudjacking is an option. A professional mudjacking company will drill holes in your patio, close to the house, then pump mud under the slab to elevate it. The mud has some cement added that hardens.
Install a Permeable Surface
Patios designed to be permeable have gaps between traditional pavers, flagstones, bricks, or wood. They are laid on a bed of gravel that allows water to drain away into the yard.
Another type of permeable patio is made with plastic. These pavers come in beautiful geometric shapes. You can also buy permeable concrete. This concrete is mixed with small stones and looks rougher. Decomposed granite is another option.
If you don’t like gravel in between your pavers, then try pavers with built-in gaps for water drainage.
Here are some great permeable paver ideas.
Improve Soil Drainage With a Popup Drain
Popup drains are another great DIY project if you are into dirt.
Popup drains are installed at the end of underground downspouts. The idea is to create a PVC pipe system to gather downspout water, then transport it downhill to a drain in your yard. The drain is designed to lay flat in your grass.
When rains come and the pipe fills with water, the drain pops up and water flows out. Underground downspouts are like French drains, but without holes. They simply carry rainwater flowing in your gutter system far away from your patio and your house.
Here’s a good description of pop up drains.
Both new and older patios (especially older patios), need proper drainage to stop water pooling on them under your dining area, seating or grill.
So if you’re installing a new patio, it’s essential that it slopes away from the house and includes some kind of drainage system as mentioned above – that can take excess water away from your home.
Retrofitting drainage to old patios can be more difficult, but there are several options you can try to help with drainage (especially on paver patios which can be lifted and replaced to build drainage channels and have space between for gravel).
Needless to say, if you try and sweep this issue under the carpet – you could end up with wet feet for your next BBQ if bad weather hits.