Calculadora de Laje de Concreto

Como Usar Esta Calculadora

1. 1Measure the length and width of your planned slab in feet.
2. 2Enter the slab thickness in inches — 4 inches is standard for patios and walkways, 5–6 inches for driveways and garages.
3. 3Click Calculate to get cubic yards needed, including a 10% waste factor.
4. 4Use the bag count for small jobs or the cubic yard total to order ready-mix delivery.

Sobre Este Material

A concrete slab is a flat, horizontal surface poured directly on a prepared subgrade, used for patios, garage floors, driveways, basement floors, and shed pads. The standard residential slab thickness is 4 inches for pedestrian-only areas such as walkways and patios. Driveways and garage floors should be 4 to 6 inches thick to withstand vehicle loads, while commercial or heavy-equipment slabs may require 6 to 8 inches or more. Proper subgrade preparation is critical for slab longevity. The ground must be compacted, level, and free of organic material. A 4-inch layer of compacted gravel (Class 5 or crushed limestone) provides drainage and a stable base. A 6-mil polyethylene vapor barrier is recommended between the gravel and the concrete to prevent moisture migration, especially for interior slabs in conditioned spaces. Reinforcement options for slabs include 6x6 W1.4/W1.4 welded wire mesh, #4 rebar on 18 to 24-inch centers in both directions, or synthetic fiber mesh mixed into the concrete. Wire mesh and fiber control shrinkage cracking, while rebar provides structural reinforcement for heavy loads. Control joints (saw cuts or tooled joints) should be placed at intervals no greater than 2 to 3 times the slab thickness in feet — for a 4-inch slab, joints every 8 to 12 feet. Concrete for slabs is typically specified at 3,000 to 4,000 PSI with a 4-inch slump. Air-entrained concrete (5–7% air) is recommended in freeze-thaw climates. Ready-mix costs $125 to $175 per cubic yard delivered. An 80 lb bag of pre-mixed concrete yields 0.6 cubic feet and costs $4 to $6, making bagged concrete roughly $300 to $400 per cubic yard — practical only for very small pours under 0.5 cubic yards.

Dicas de Instalação

• •Compact the subgrade and add 4 inches of gravel base before pouring — this prevents settling and cracking.
• •Set forms with stakes every 2 to 3 feet and check for level; oil the forms for easy removal.
• •Place reinforcement (wire mesh or rebar) on chairs so it sits in the lower third of the slab, not on the ground.
• •Pour concrete in one continuous operation to avoid cold joints — have enough help and equipment ready before the truck arrives.
• •Finish with a bull float, then broom the surface for traction before applying curing compound.

Erros Comuns a Evitar

• ⚠Skipping the gravel base — pouring directly on soil leads to uneven settling and cracking within the first year.
• ⚠Making the slab too thin — 3-inch slabs crack easily under any load; always pour at least 4 inches for residential use.
• ⚠Placing wire mesh directly on the ground instead of on chairs — reinforcement on the bottom does nothing; it must be in the lower third of the slab.
• ⚠Forgetting control joints — without joints every 8 to 12 feet, the slab will crack randomly as it shrinks during curing.
• ⚠Finishing the surface while bleed water is present — this traps water in the top layer and causes scaling and dusting.

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