Table of Contents
Can you pour concrete directly on dirt?
Long story short, yes you can pour concrete over dirt.
What is the best material to put under concrete?
What is the Best Base for a Concrete Slab? Most people build a driveway or a patio so in that case, a good choice would be a mix of coarse and fine aggregate which will create a compactable base. Overall, a mix of crushed stone and stone dust is the best base material for any concrete flatwork.
What do you put under a concrete patio?
You do need gravel under a concrete slab, footing, or patio. Gravel provides a solid foundation for your concrete as it can be compacted. It also improves drainage, preventing water from pooling beneath the concrete.
What do you put down before laying concrete?
To shore up the subsurface, sprinkle a thin layer of cement sand onto the gravel and dampen it with water. Do not leave any standing water and allow the dampened sand to dry for about an hour before pouring the concrete. Ground preparation is key to pouring sidewalk, driveway or any other concrete slab.
Do you need gravel under concrete?
Whether you pour concrete for a walkway or patio, a strong gravel base is required to prevent the concrete from cracking and shifting. Gravel is especially important in clay soil because it doesn’t drain well, which results in water pooling under the concrete slab and slowly eroding the soil as it finally drains.
Does a concrete patio need footings?
A concrete patio does not require concrete footings. Footings are usually used as a structural component to support the building’s loads and distribute them to the ground. Since a patio is relatively light and does not have a structure on top, you do not need to excavate and have footings built to support it.
Is sand a good base for concrete slab?
Simply put, sand isn’t sturdy enough to work well as a subbase for something like a driveway. It is also difficult to maintain a level sand surface when pouring concrete, and therefore difficult to maintain a uniform thickness of the concrete slab.
What happens if you don’t put gravel under concrete?
Because concrete is a very porous material, it will absorb any moisture that it contacts. This can cause pooling. Without crushed stone, pooling water will settle under it and erode your slab.
What kind of gravel do you put under concrete?
Depending on what the driveway will be used for, the base may need to be 4 to 12 inches. Ideally, 6 inches of crushed stone or gravel should be used for most driveways. Proper application requires that the driveway hole be dug out, and the soil has to be prepared.
How do you level the ground for a concrete slab?
Tamp down the surface with either a hand tamper or a machine tamper. Pack the soil until you can no longer see a footprint when you walk across the surface. If adding gravel, pour the gravel base and tamp it down to pack it tightly. Check for level again.
Do you need rebar for 4 inch slab?
The thickness of rebar should be no more than 1/8 that of the slab, so a 4” slab shouldn’t have steel greater than #4 or 1/2″ bar. It’s best to check with a Structural Engineer if your slab will bridge or cantilever. What is this? For 4” concrete slabs used for driveways and patios, #3 rebar is common.
How many yards of concrete do I need for a 24×24 slab?
For example, for a concrete slab that is 24′ X 24′ X 4”, simply enter 4 in the Thickness/Depth field, 24 in the Width field, and 24 in the Length field. Click “Calculate”. Your answer should be 7.11 yards. Note: The Concrete Volume Calculator can also be used to determine yardage for aggregate products.
How thick should a concrete patio be?
Four inches is the minimum thickness for a concrete patio. You’ll want to make it six to eight inches thick if the patio will support a structure such as a gazebo or hot tub.
Do you need a vapor barrier under a concrete slab?
Exterior concrete slabs or those in unheated structures don’t require a vapor retarding barrier. However, if the surface will be sealed with an impermeable membrane or product, there should be a vapor barrier under the pad.
How deep does a footer need to be for a patio?
Dig a hole roughly 24 inches in diameter. If you’re using a smaller tube form, dig the hole twice the diameter of the form. Dig the hole to a depth 6 inches below the desired position of the form’s bottom. For example, if your footing depth requirement is 12 inches, dig the hole 18 inches deep.
How deep should footings be for a patio?
Laying patio foundations You need to allow 150mm for foundation mix and paving, and if you are laying directly next to a house then the finished patio should be at least 150mm below the damp proof course. This means you will need to dig out the area to a minimum depth of 300mm below the damp proof course.
Do I need a foundation for patio?
Before you start laying tile or stone for a new patio, you need to build a foundation. With a proper foundation, your patio will last for years. Without one, your patio stones or tiles will shift and crack. A mortarless patio foundation uses compacted sand and gravel as a base rather than concrete.
