What kind gravel under concrete

Without crushed stone, pooling water will settle under it and erode your slab. Adding a layer of crushed stone will add proper drainage , as well as create a barrier between your slab and the ground.

For added protection, consider adding a vapor barrier as well. Over a long enough time, concrete is prone to cracking. A flaw that can lead to unevenness. So while this is typically caused because of movement and shifting in the ground due to poorly compacted soil, or soil type , a layer of crushed stone will greatly reduce the chances of this happening, and increase its longevity. Email Address. There is no question that pouring concrete directly onto the earth saves time and money, but you are much more likely to get cracks in your slab as the earth shifts.

Even if you live in a warm climate, the shifting of the earth from warm to cool or from dry to wet is enough to cause cracks in a slab. When compacting gravel designated for a foundation of a concrete slab, it is best to use a machine. A plate compactor or jumping jack will compact the gravel in a fraction of the time that it would use to use a hand tamper. Compactors are widely available at any rental store.

Big box stores that do rentals will almost certainly have one — or many — to rent by the hour. While heavy, they are small enough to be loaded into the back of a family van or truck without much hassle. Rigid foam is different from the insulating foam you would use in your walls. Foam for subfloors is much sturdier and can be walked on without risking cracks or breaking.

It is ideal for placing on top of gravel foundations and withstanding concrete pours. The foam will have a tremendous impact in terms of the insulation of your floor. If you intend to heat the space above your concrete slab, it is imperative you use foam beneath the slab. As a barrier between the cold of the earth and the slab, it will help your slab retain heat much, much longer in the winter.

When using rigid foam, make sure the vapor barrier goes above rigid insulation so that concrete does not get beneath insulation when pouring. If that occurs, it could lift part of the insulation and make it protrude through the top of the slab, causing cracks as the concrete settles and compromising the ability of the board to insulate the slab completely. Pouring a slab is a lot of hard work and very time-consuming. But anything that is supposed to last for years and years should be hard work.

Therefore, if you are going to take the time to pour a slab, invest a little more money and add some gravel. The addition of foam on top of your compacted rock is just another layer to act as a preventative measure against cracking and shifting. Plus, a properly built slab can have a lifetime of uses. Thanks for taking a moment to look at this article. Hopefully, it answered all your questions about what should go under a concrete slab. If you have any other suggestions or noticed anything I left out, please drop me a line below.

Best of luck with your next concrete slab project! Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. The answer of what is a off form concrete you can find in this article and many other answers considering off form concrete.

Paint costs for painting your concrete driveway and what type of paint to use, and the cost in Australia. What Gravel to Use Under Concrete []. Table of Contents Hide. What is the Best Base for a Concrete Slab? What Size Gravel is Best for Concrete? Why is a Concrete Slab Base Necessary? What Material is Used for a Slab Base? Subscribe to our Weekly Newsletter.

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Benefits The answer of what is a off form concrete you can find in this article and many other answers considering off form concrete. Concrete Paint Prices Paint costs for painting your concrete driveway and what type of paint to use, and the cost in Australia.