You know how time-consuming and difficult it is to do any kind of renovation outside of your home. There are many ways to cut corners and save time, such as pouring concrete over the grass for a project instead of clearing the vegetation first.
Concrete should not be poured directly over grass. In order for your concrete to harden flat and smooth, you should remove all vegetation and pour the concrete on top of a smooth, debris-free surface.
Making of freshly poured cement on a concrete pavement sidewalk in a new home
If you leave grass under your concrete slab, you could face some unnecessary problems in the future. We’ll discuss these potential problems in this article as well as best practices if you decide to pour concrete over grass.
Why You Should Not Pour Concrete Over Grass
Pouring concrete requires you to make sure the surface is flat, and the soil is free of debris. The ground must be compact and strong.
Grass Regrowth Leads to Cracking
In order to pour concrete over a previously grassy area, dig down at least a few inches into the soil. To prevent regrowth, you should not only remove the visible grass blades but also get down under the roots.
If roots of grass or weeds are left in concrete cracks, regrowth could occur. The grass will probably not be strong enough to crack the concrete, but it can find minuscule cracks in the concrete and push its way through, causing a more noticeable split.
You’ll have an uneven foundation
If you pour concrete on grass without creating a solid foundation, you are almost certain to encounter problems as soon as the concrete dries.
Once your concrete starts to dry, it settles and pushes its weight into the ground. If the area you are pouring concrete in is not even all the way around, the concrete will not be either. There will be cracks in the slab where the pressure is too great for the slab to support. If you’re going to use this concrete for a hot tub, but it’s uneven, don’t worry; there’s still a way to make it work.
Concrete Requires a Gravel or Sand Base
Pouring concrete requires a base of sand or gravel. The weather doesn’t affect sand or gravel, which means your concrete slab won’t expand or contract when the temperature changes and, therefore, will be less likely to crack. If you use grass instead of this layer, your base is more likely to shift over time.
Note: It is not necessary to do this if your natural soil is mixed with gravel or sand. By simply removing some grass completely, the ground will be ready for the concrete to be poured.
Is it okay for concrete to be poured on grass?
When putting concrete over grass, there are no guarantees. When a root is alive, it is compelled to keep searching for a way up, regardless of the barriers in its way. If you’re in a rush or simply don’t want to deal with the hassle of removing all that grass, there are a few scenarios when you might be able to get away with leaving it alone:
If you pour more than 6 inches of concrete: it may not prevent grass from coming up through your concrete pad, but it will take longer for it to do so.
If it’s only temporary: If you plan to remove the concrete from its current location within a year or two, pouring it on the grass won’t be a problem. It will continue to develop, solidify, and retain its tensile strength.
If you don’t mind maintaining the concrete, you can pour it over the grass in these circumstances. Filling cracks and gaps is a simple and inexpensive DIY project.
If cracks and an uneven surface aren’t a concern: If you’re pouring concrete as a basis to support tiny items such as air conditioners, outdoor utilities, or even your mailbox, little cracks and a slight tilt might not be an issue.
How to Pour Concrete Over Grass Directly
If you do end up pouring concrete on your grass, make sure you follow the appropriate processes so you don’t have any problems with your new slab afterward.
Before you begin, make sure you know where you’ll be pouring your concrete. Even if you have a wonderful idea in mind, you may not appreciate the results if you don’t have dimensions and visual details. You’ll also want to make sure you’re using the correct concrete mix for the job.
Best Concrete for Pouring Over Grass
When choosing the best concrete for pouring over grass, look for concrete that is designed for outdoor use. A quick-dry concrete that simply requires water before pouring is the best option for this. You should also look for concrete that has the following characteristics:
Dries in 24 hours: This eliminates the chance of accidentally drying footprints (or paw-prints) in your pad. It also protects the pour from adverse weather such as rain or windstorms.
Easy to use: Most quick-drying concrete should only require water for mixing; you don’t want anything that takes multiple processes. This is to avoid any mistakes that could result in a huge amount of concrete mix being ruined.
High-quality concrete mix: You want a proper blend of rocks, sand, water, and concrete in your concrete mix (water and concrete create the “paste”). The optimum mix will contain a high percentage of small rocks and a low percentage of concrete (about 15%).
The following brands are well-known for their grass-friendly characteristics:
Quikrete: This concrete is simple to apply, long-lasting, and hardens in just 24 hours.
Sakrete: This is a low-cost, professional-grade quick-setting concrete solution that can be ready for foot traffic in as little as 6 hours.
MasterCraft: This concrete dries 90 percent faster than other concrete mixes and is extremely cost-effective. This is a high-strength concrete product that is ideal for your garden projects.
Till the Existing Grass
Till the existing grass the entire length of your walkway or to fit the size of your project. Ensure that you till the grassroots and shred them entirely to eliminate the possibility of their growing back.
Pour Your Concrete
It is imperative that the concrete is mixed and poured properly:
1. Mix the dry concrete with water, saturating the entire mixture thoroughly.
2. The next step is to board off the areas where concrete will be applied with wooden planks so that the concrete is perfectly edged.
3. Fill the boards with concrete, being careful not to let the mixture overflow or move the boards. It is crucial to completely cover the area of grass and soil where the slab will be placed.
4. Add a few inches of depth to your concrete to ensure it will not crack under pressure.
5. Be sure to allow plenty of time for the boards to dry before removing them.
If the area around the pad is uneven or slanted, you can add decorative stones or mulch. This will hide the imperfections and provide the area with a beautiful appearance.
It is a good idea to remove all grass and debris before pouring concrete, even if certain projects allow you to leave grass underneath. For many years, you will have an even, smooth, crack-free look without having to deal with any expensive or time-consuming maintenance.