If done properly, new concrete can
often be poured
right over an existing slab
. For this to be feasible, the contractor needs to pour
at least 2 inches
thick, use smaller aggregate, and incorporate reinforcement such as welded wire mesh or fiber mixed into the concrete
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One may also ask, how thick should I make my concrete slab?
Standard concrete floor slab thickness in residential construction is 4 inches. Five to six inches is recommended if the concrete will receive occasional heavy loads, such as motor homes or garbage trucks. To prepare the base, cut the ground level to the proper depth to allow for the slab thickness.
Event, do you need rebar in a patio slab? Do concrete patios need rebar? Even though it's possible to build a concrete patio without rebar, it's not recommended. All concrete is subject to cracks, but rebar holds all the cracks together and keeps the slab level and even. Without rebar, the cracks would become quite wide and the concrete would become uneven.
By no means, how strong is a 2 inch concrete slab?
How strong is 2 inches of concrete? A common bag of concrete, for example, may have a compression strength of 4,000 psi, based on a thickness of 2 inches after it has set for 28 days. Other concrete may have a compression strength of only 550 psi.
Do you need rebar for 4 inch slab?
No, you do not need rebar for a 4-inch slab of concrete on grade. A 4-inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required. Rebar is recommended on concrete measuring 5 – 6 inches thick.
13 Related Questions Answered
Enter the size of the slab you want to build in square feet. The calculator will indicate the number of 60 or 80 pound bags of QUIKRETE® Concrete Mix you need to build a 4″ or a 6″ slab. (All yields are approximate and do not include allowance for uneven subgrade, waste, etc.)
Four inches is the general rule for residential areas, and it can hold several regular-sized cars without the homeowner having to worry about cracking.
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.
Rebar is recommended for concrete that measures 5-6 inches in depth. The type of and intended use of concrete impacts the need for rebar reinforcement. Rebar must be placed at the center of or slightly above the center of the concrete slab—hence why it should be a certain thickness for best results.
No, they do not. Larger projects or slabs may need steel reinforcement to provide support or extra strength. Wired mesh can also help resist cracking. However, not every piece of concrete necessarily requires that extra boost.
Considering the support constraint, rebar is undoubtedly stronger than wire mesh. Several constructors consider rebar for domestic jobs. For thicker driveways and locations that involve greater traffic, rebar is always a good option to consider.
If the slab is too thin, it may break under load and fail before its time. If the slab is too thick, it costs more than it should. Slab thickness is a major factor in the cost of a concrete floor, so there's often pressure, which can become intense, to make the slab as thin as possible.
Slab thickness requires a minimum clear distance of one-twelfth the distance between the ribs and not less than 2 inches.
The weight of concrete is approximately 150 pounds per cubic foot, or 4,050 pounds per cubic yard. The formula for calculating the weight of concrete is: Length (in feet) x Width (in feet) x Thickness (in inches) /12 x 150 = weight (in pounds).
Construct the form with 2x4 or 2x6 lumber and secure in place by wood stakes and deck screws. Excavate the slab area to a depth of about 7 inches, allowing 3 inches for a gravel base and 4 inches for concrete.
Recently, though, research has shown that the old traditional layer of 6-mil Visqueen (polyethylene plastic) under the slab is seldom effective for two main reasons: Although it may seem water-tight, this grade of material allows a lot of water vapor to pass through.
To pour a typical 10x10 concrete slab will cost $670 to $930, a 12x12 slab for a patio will cost $796 to $1,476, a 20x24 driveway slab runs between $1,440 and $3,360, and a 24x24 slab for a garage will cost $3,058 to $5,944. Get free estimates from concrete companies near you.
Now you can judge what is better - directly laying conc over soil or soil should be overtopped by a sand layer. No, Because concrete slabs “float” on the soil, soft ground or voids underneath may cause unsupported areas to crack under heavy weight like vehicles.