How Thick Does a Concrete Slab Need to Be for a Patio?

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    Deciding the Thickness of your Patio’s Concrete Slab

    A patio’s best feature is that it has next to zero maintenance. Though you do need to put in a few fine touches here and there, you really don’t have to do much to keep up the appearance of your outdoor escapade.

    This varies from one type to the next.

    Three of the most commonly chosen patio types include the paver, stone and concrete slab patio. Among the three, the easiest to sustain are those made out of concrete. While they come in many forms, the concrete slab is the best option to go for when you are looking for a flat, smooth and stable patio that gives you thermal heating and the best flooring to work with.

    Being the best option naturally has its drawbacks. While it may seem to be quite simple, constructing a Concrete Slab for your patio can be complicated in itself. Don’t even get me started on the concrete composition, placement and measurement to get the slab into place. On top of that, timing and proper setup of your concrete slab is essential for the stability of your patio floor. That said, let’s dig into all the details before you get started.

    All you need to know

    As the most durable, sturdiest and most reliable way of creating your patio, a concrete slab requires a lot of precision and accuracy when it comes to the measurements and content ratio. From atop it might seem like cement poured on topsoil, but below all that is a whole new world of construction.

    While some opt to just fit in a concrete slab over a shallow pit, this isn’t exactly a sensible way of working on your patio. Constructing it on soil alone cannot assure you stability. Even if your slab is perfectly measured, a gap in the ground, a protruding rock or simply weak topsoil could make it crack under pressure. This is especially the case with patios located in extremely high or low temperatures.

    You could, of course, have it repaired, but unlike pavers and bricks that can be replaced right away, a cracked concrete slab isn’t as easily patched up. Filling in a crack is possible, however when things do get out of hand, such as weeds pushing their way through the crack or the lines extending further down the line, the only option you have is to replace the whole slab itself.

    That said, before you start digging around your backyard, it would be best to get your numbers right the first time around.

    (Second guessing whether to build a patio or a deck? Check out this article to find out is it cheaper to build a deck or a patio!)

    Back to the Basics

    A good building always needs a good foundation. The same goes for your building your concrete patio. Even if you cannot predict how soil will shift over time, creating a cushion for your concrete slab helps lessen the effects any movement will cause.

    A gravel base is the most common and practical support to work with. And while it may be tempting to just pour everything about, this actually determines how thick your concrete slab should be. While you could use a 1:1 ratio for you slab and gravel duo, you could always turn to a concrete slab calculator or professional to get your numbers sorted out.

    It is advisable however to stick to 4-6 inches of gravel as your foundation. Should you go with the minimum of 4 inches, you with need to work your way through an 8 inch pit minimum.

    Does this mean you can mess around with your slab? Just how thick should patio slabs be?

    Despite having a great foundation, a house is bound to crumble and fall apart if created with substandard materials and inaccurate measurements. With this logic, your patio, will undergo the same if you decide to follow suit with people who forget the details in their rush to get their dream patio in place.

    Even if you have concrete patio ideas for small yards, every single detail must be meticulously planned out, else you end up with a patio that won’t even last you a month before you have to start working on repairs. It is essential that you keep your concrete slab at no more than six (6) inches of thickness. Also, it would be best to work the numbers out if you wish to work with any lesser as you can only put in one slab. If you want to put new concrete over old concrete check out all you need to know first. Because not only is it bad to put one on top of another, putting in two concrete slabs for your patio floor is bound to fail. Think of it this way, it two different concrete slabs were to be meshed together, the shift in top soil could cause both to rub off one another. This could result to a premature cracking in your concrete slabs.

    Also, that would really be way much work. (Want to get someone else to do it for you? Check out this article on concrete patio contractors!)

    In conclusion, if you want to work your way around a concrete slab for a patio floor, you’re better off taking your time, effort and attention on the details rather than rushing things through. After all, nothing good comes out of rushing things. And if you are ever in a struggling situation with your patio, All Pro Decks is here to help!

    Justin Wylie

    Justin Wylie, owner of All Pro Decks & Patios is a Deckorators® Certified Pro Elite located in the San Antonio Hill Country area. He specializes in building decks, patios, patio covers, pergolas, concrete slabs, fireplaces and more while providing quality and service for his customers.

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