Do I need gravel under concrete slab?

A 60-pound bag yields . 017 cubic yards, and an 80-pound bag yields . 022 cubic yards. For a 10 x 10 slab, you would need 77 60-pound bags or 60 80-pound bags.

How many concrete bags would I need for a 8 ft x 8 ft x 6" slab? 54 x 80lb Concrete bags. How much does it cost to pour a 8'x8' x6" slab? Ready-mix costs approx $277.86.

With a brief look, a 16x16 area at 6 inches deep, you would need approximately 6.73 tons or 4.74 cubic yards of gravel. Concrete reinforcing is also recommended in high traffic areas and medium to large areas.

You do not need rebar for any slab if you make it thick enough and space the joints properly. Rebar in jointed pavement is there to counter the cupping effect of thermal expansion. I always recommend the use of rebar or at least rewire. Any concrete slab can crack.

With a brief look, a 20x20 area at 6 inches deep, you would need approximately 10.52 tons or 7.41 cubic yards of gravel. Concrete reinforcing is also recommended in high traffic areas and medium to large areas.

The good news is that you can pour the concrete in water. ... The biggest issue with pouring concrete under water is movement. If the water is moving, it can wash away the cement paste that's holding the sand and gravel together. But if the water is calm, then it's not a problem at all.

Signs Of A Leak Under Concrete1). There is water or damp spots on your floor. If hot-water lines are leaking, this may also lead to warm spots on your floor. ... 2). You can hear the sound of rushing water underneath your floor. ... 3). There is a significant increase in your water bill.Jan 10, 2021

Most exterior slabs do not need a vapor barrier. ... In general, place the concrete slab directly on top of the vapor barrier, with the subbase below. ... The vapor barrier can be placed under the subbase, if the building is closed in when the dry subbase material is placed.More items...

Concrete is strong in compression, but not under tension. So, if it flexes, like a slab with a vehicle on top of will do, it cracks at the bottom whre the flexing becomes tension. ... Mesh will help mitigate the chances of cracking of the slab due to differential settlement.

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.

Under ideal circumstances, acid etching works to expose the pores of the concrete. However, acid etching won't remove glues, mastics, caulk, and common stains, If your floor is marred or stained by these substances, you'll need to resort to grinding at least part of your floor.

Average Cost To Pour Concrete 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.

You don't need any cement board under the tub. It is far more important to have a sturdy layer of ply under the tub.

How many concrete bags would I need for a 5 ft x 5 ft x 6" slab? 20.8 x 80lb Concrete bags.

Laying a concrete driveway over an existing gravel one is possible, but it is not generally recommended. ... The kind of gravel that is intended to go under cement is typically a smaller grade than what is used for gravel driveways.

A hot tub requires a stable surface — whether it's a concrete slab, reinforced deck, or firmly compacted soil with crushed gravel.

There's also the option to have the hot tub installed in the ground but that still requires a concrete vault..

edit - To put footings under the slab, you can cut holes wherever needed, excavate for footings (Sonotubes or concrete piers or similar) and then patch the concrete slab.

Creating an insulation layer and a vapor barrier between the concrete slab and the ground beneath it is the best practice in insulating basement floors.

The insulation barrier will help keep warm air in, and the vapor barrier will keep unwanted moisture out..

A 50mm thick layer of proprietary floor slab insulation is usually enough to reach and maintain the target U value but this should be checked with an architect first. Insulation sheets should be laid tightly together with the joints staggered to avoid movement.

You don't need any cement board under the tub. It is far more important to have a sturdy layer of ply under the tub.

Applying a bead of polystyrene-compatible caulk or mastic to the top of the insulation board minimizes water infiltration behind it. For under-slab applications, the rigid foam insulation typically should be installed over a gravel base, with a poly vapor diffusion retarder between the gravel and insulation.

To create the base, spread a 4-inch layer of gravel over the excavated area. Level the gravel, following the initial grade, and cover it with a 1-inch layer of sand. Tamp the gravel and sand down with a plate compacter before laying the blocks.

Pour concrete over a solid, well-drained base Because concrete slabs “float” on the soil, soft ground or voids underneath may cause unsupported areas to crack under heavy weight like vehicles. Pack about 4 in. of sand or gravel over clay and other poorly draining soils to provide even support.

Registered User. permanent wood foundations require gravel, not concrete or soil for the footings - every situation is a little different, but all footings need to bear on the soil/gravel/bedrock/ whatever is supporting the structure equally, or it's going to settle at different rates.

10 x 10 = 100 square feet. 4 ÷ 12 = .33. 100 x .33 = 33 cubic feet. 33 x .037 = 1.22 cubic yards.

Your project is 32 square feet at a depth of 4”. Here is the quantity that you will need for your slab. Quikrete Concrete Mix: 24- 60lb bags.

Do I need a DPM under laminate flooring? Simply put yes. In order to prevent damp rising through the concrete floor and causing issues, a DPM should be used under all final floor types including wood flooring, laminate, vinyl and floor tiles.

InstructionsDig Under the Concrete. Dig out the soil, gravel, or other material from under the concrete, using a shovel and a pickax. ... Strike the Concrete. Lightly sprinkle the concrete with water to minimize dust. ... Pry Off Stubborn Pieces. ... Move the Concrete Chunks With a Hand Truck.Feb 19, 2020

And yes, mesh is important: Concrete is strong in compression, but not under tension. So, if it flexes, like a slab with a vehicle on top of will do, it cracks at the bottom whre the flexing becomes tension. Steel mesh will prevent this to a large degree and hold it all together.

You really do not want the patio level with the house threshold, too easy for water to get in to the house. As for the slab, it will not settle if you prepare the subgrade correctly. You need the footers to support the structure, the slab is just there to walk on, and has no structural importance.

Concrete can and does absorb moisture, which makes the area underneath the pavers ideal for the development of mold, mildew, moss, and weeds. This can lead to these problems spreading in between the paver joints and onto the surface of the pavers.

Installing pavers is very similar to concrete installation. You must start with a solid base and foundation. Most frequently, this involves digging down into the ground and removing the existing dirt and replacing it with gravel and sand.

Yes! A strong gravel base is required when building a concrete patio in order to prevent the concrete from shifting or cracking. Adding gravel under the concrete also provides a level surface for your foundation and adds proper drainage when there is pooling water.

In California they place sand between slabs and plastic vapor barriers—in Florida they don't. Almost everywhere (except “California”) that slabs are placed on the ground—a plastic sheet—a vapor barrier—is located directly under the concrete slab and on top of the ground (Photograph 1).

Registered User. permanent wood foundations require gravel, not concrete or soil for the footings - every situation is a little different, but all footings need to bear on the soil/gravel/bedrock/ whatever is supporting the structure equally, or it's going to settle at different rates.

One reason it is used as a backfill or sub-grade material. As with all material, it has to be placed correctly and compacted properly. Sand needs to remain damp as well as other material before placement of the concrete. If you want to build a road, use gravel, but this does not mean you will not have issues.

Cement is actually a very porous material and can easily absorb water. Therefore, any concrete that may come into regular contact with water, such as under tile or for a pool, will need to be waterproofed. If cement is not waterproofed, it can cause issues with the mortar used between the tiles.

For a 10 x 10 slab, you would need 77 60-pound bags or 60 80-pound bags. If we add an extra 10%, that's an extra 8 60-pound bags or 6 80-pound bags.

Excavate the slab area to a depth of about 7 inches, allowing 3 inches for a gravel base and 4 inches for concrete.

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.)

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..

InstructionsDig Under the Concrete. Dig out the soil, gravel, or other material from under the concrete, using a shovel and a pickax. ... Strike the Concrete. Lightly sprinkle the concrete with water to minimize dust. ... Pry Off Stubborn Pieces. ... Move the Concrete Chunks With a Hand Truck.

5 Bags# It takes approximately 5 Bags of Portland cement, 8 cubic ft of sand, and 20 cubic ft of gravel to make approximately 1 cubic yard (27 cubic feet) of concrete.

Here is the quantity that you will need for your slab. Quikrete Concrete Mix: 24- 60lb bags.

An average 1:2:3 mix contains one part cement, two parts sand and three parts gravel. To make 1 cubic yard of concrete, you'd need seven 94-pound bags of cement, about 1/2 cubic yard of sand and just over 3/4 cubic yard of gravel. The amount of water you use depends on how wet the sand is.

Concrete Slab Prices By SizeSlab SizeSquare FeetAverage Cost Installed15x15225$1,38820x20400$2,46824x24576$3,55420x30600$3,7026 more rows

Laying a concrete driveway over an existing gravel one is possible, but it is not generally recommended. ... The kind of gravel that is intended to go under cement is typically a smaller grade than what is used for gravel driveways.

Laying a concrete driveway over an existing gravel one is possible, but it is not generally recommended. The kind of gravel that is intended to go under cement is typically a smaller grade than what is used for gravel driveways.

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.

In fact, most professional shed slab builders will install a polyethylene membrane under a shed concrete slab even if it is not specified. The reason is that the vapour barrier stops moisture from the wet concrete escaping into the ground under the concrete.