Can I put a lawn on top of concrete? Has been a long debatable question between gardeners for years.
And there is a good reason why…
Grass roots grow up to 6 inches long, so for the grass to be healthy and to sustain itself, there needs to be at least 6 inches of soil. Adding 6 inches of soil on top of concrete can cause a whole host of problems, from drainage issues, soil dehydration and constant maintenance.
As a matter of fact, if your concrete base is just outside your back door, the drainage issue could actually damage your home!
Can I Put a Lawn On Top Of Concrete? – 5 Reasons Why You Shouldn’t!
1. Drainage – That water has gotta go somewhere!
Sometime in your life you must have walked across a waterlogged lawn or field?
Agree with me, it’s like a swamp! trainers get ditched, socks get wet and it just gets worse and worse with every step!
This is what will happen if you put a lawn on top of concrete.
Concrete is impervious to water, so everytime it would rain, and everytime you water your lawn, the water level would just rise and rise until your lawn would become waterlogged.
Now if your lawn is laid on a concrete base just outside your back door, this extra water is going to cause some major damage to your exterior walls.
You see bricks are a porous material and they will absorb water. The constant saturation of water will then work its way through the brick and start to affect the structure of your house.
It will most definitely cause rising damp within your house walls and cause a whole host of other problems, including mold.
Or if the lawn you want is going to be laid on a patch of concrete further up the garden you won’t have to deal with the above problems, but you will have to deal with this….
2. The Smell – Urgghhh!
Now you know concrete is impervious, which means the water cannot drain through it, so the only thing it can do is evaporate.
Now if there is too much water and its the autumn/winter months, it ain’t evaporating, not a chance!
So the water then becomes stagnate (can’t move anywhere)
The stagnate water will cause the lawn to smell, and I mean really bad! To the point it smells like rotten eggs!
I remember a local park near where I grew up had a pond.
It would have fallen leaves, sitting on top of it and overgrown grass growing into it and the smell was unbearable from spring onwards.
Your lawn on top of concrete would smell exactly the same!
3. Grass Health – Goodbye Green, Hello Yellow
Be prepared for your lawn to have a short lifespan.
A normal lawn has healthy soil, and if you didn’t know, healthy soil is full of air, which helps your grass roots breathe.
When there is too much water in the soil, the air will travel up to the surface and escape.
Your grass roots will begin to drown because there is no oxygen for them to breathe, which inevitably causes your grass to die.
Turning your lawn from that lovely green colour to a deathly yellow colour because the water had nowhere to go.
4. Maintenance – You Will Throw The Towel In!
You’ve took the leap and put a lawn on concrete, your lawn has survived through the autumn and winter months, survived the numerous rain falls, and now it’s spring.
Spring is the time you drag out the lawnmower and make your first cut.
You wheel your mighty Briggs and Stratton on to your lawn, pull the starter and it rev’s into action!
You begin to push and you realise instead of cutting the lawn your sinking and becoming a bulldozer to the lawn, the blade is chopping away at the grass and the soil, Jeez it’s a mess!
The lawn is absolutely saturated from the winter months!
What can you do?……I’m afraid not alot.
The only thing you can do its wait for the water to start evaporating through the spring as the temperatures rise and the sun gets higher.
But the next problem will be the lawn drying out too quickly through the summer months.
Concrete is really good at absorbing heat, and not only do you have the heat from the sun and now from the concrete, the water will evaporate at a much faster rate than a normal lawn.
Rest assured watering a lawn on top of concrete through summer will be relentless, everyday and numerous times of the day task!
5. A Waste Of Money – I Guess You’ve Gathered That?
I’m sorry if I’ve left you disheartened.
But your better off saving your money and either…
1. Have the concrete patch broken up, taken away and a proper lawn laid.
2.Keep the concrete block and have artificial grass laid instead.
They are both costly alternatives, but even having a lawn on top of concrete is just as costly, as I will show you…
This material list is based on putting a lawn on a concrete pad 5m x 5m with 6 inches of soil (for the roots remember).
To make it simple, I’m going to choose Wickes here in the UK to price the materials up, so let’s go…
Soil & Sand
First of all I used a soil calculator to find out how much soil I will need:
I will need 6 bulk bags of soil, but we will also be mixing sand into the soil to help with germination, and conditioning etc.
The usual rule of thumb is 2 shovels of soil to 1 shovel of sand, or 2 bags of soil to 1 bag of sand, also called a 2:1 ratio.
So if we follow that 2:1 ratio we will need 4 bulk bags of soil and 2 bulk bags of sand
4 bulk bag of soil from Wickes cost £500 and 2 bulk bags of sand cost £84
Timber will help contain the soil within the boundaries of your concrete pad
Because this concrete area is going to be square I will need 16 lengths of 3×3 timber. Wickes sell these at 2.7 metres long so there will be some left over off cuts.
16 lengths will give 6 inches in height when two posts are laid on top of each other.
Fence posts will be great for this because they will be treated and not overly priced!
Also securing them with tooth plate connectors and screws, to make it really easy!
16 Fence posts from Wickes will be £208.
The tooth plate connectors will come from Tool station for £5.74 in a ten pack. We will need 2 packs totaling £11.48
Also a pack of 200 screws from Tool Station at £3.98
Using a turf calculator I will need 25 square metres of turf…
Wickes sell there turf at £6 per 1 metre squared, so I will need 25 rolls totaling £150
***please note that the above prices were correct at the time of writing this post***
£957.56 in total materials would, like I said, be a total waste of money!
Put the money away and think about the other alternatives, you could (even though it’s not grass related) afford the materials for 5m x 5m decking for the same or slightly less price, now that’s another alternative!
Did This Post Help?
I hope this post helps to encourage you not to waste your money putting a lawn on top of concrete?
Friends and family may say go for it, but don’t chance it.
Over nine hundred pounds towards artificial grass would be, by all means, a better investment for your property.
Little to no maintenance, so you have more time to relax and entertain, but it may need hoovering from time to time 😉
Each and every week I put my heart and soul into providing you with great content to help with any DIY jobs around the home.
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