How much wire mesh do I need for a concrete slab?
A 20 × 20 ft slab, with the mesh kept 2 inches from the edges and lapped 8 inches, takes 5 strips × 19.7 ft = 98.3 ft of roll (0.66 of a roll), so buy one 5 × 150 ft roll of 6×6 W1.4 mesh and keep the remaining third for another job. In 8 × 20 ft sheets it is 3 sheets.
How to work it out
- Area inside the edge distance: 387 sq ft
- 5 strips × 19.7 ft = 98.3 ft of roll (0.66 of a roll) ÷ 150 ft per roll = 1 piece
- × 149.81 lb each = 150 lb
Mesh math is all about how pieces overlap. A 20 ft square slab is a good example because it shows how rolls and the two common sheet sizes compare.
Adjust for your project
- Layout
- 5 strips × 19.7 ft = 98.3 ft of roll (0.66 of a roll)
- Area to cover
- 387 sq ft
- Weight of the mesh bought
- 150 lb
- Mesh does its job only if it ends up inside the concrete. Set it on chairs or blocks at the height your plans show — pulling it up with a rake during the pour is unreliable.
- Flatten rolled mesh before you place it; it wants to curl back into a roll.
Mesh for a 20×20 slab by product (8 in laps)
| Mesh product | Sheets or rolls | Weight of the mesh bought |
|---|---|---|
| Roll, 5 × 150 ft | 1 piece | 150 lb |
| Sheet, 5 × 10 ft | 15 pieces | 150 lb |
| Sheet, 8 × 12½ ft | 6 pieces | 118 lb |
| Sheet, 8 × 15 ft | 6 pieces | 141 lb |
| Sheet, 8 × 20 ft | 3 pieces | 94 lb |
Roll or sheets for 400 square feet
Each 5 ft strip covers about 4⅓ ft once it overlaps its neighbour by 8 in — one 6 in mesh square plus 2 in, the lap ACI 439.5R gives for plain welded wire. Across 19.7 ft of slab (2 in back from each edge) that takes 5 strips of about 19.7 ft each — 98 ft of roll, about two-thirds of a 150 ft roll. One roll (about 150 lb of W1.4) does the job with 50 ft to spare for a walkway or the next pad.
8 × 20 ft sheets are the tidy alternative: three sheets, lapped 8 in at the two joins, cover the slab flat with no curl to fight. They weigh 31.39 lb each, about 94 lb in all — but they are long, so arrange delivery or bring a trailer. The small 5 × 10 ft sheets would take 15 here.
Before the pour
Tie the laps with wire so pieces don’t shift, and set the mesh on chairs at the height in your plans. If your plans call for rebar instead of mesh, see how much rebar for a 20×20 slab. The concrete for the same slab is on how much concrete for a 20×20 slab.
Different size? Use the full Wire Mesh Calculator.
What you’ll need
- Rebar chairsBudget price
Hold rebar or mesh off the ground so it ends up inside the concrete, not under it. Match the chair height to where your plans place the steel.
See options on Amazon (opens in a new tab) - Rebar tie wire and twisterBudget price
Ties bars together where they cross so the grid stays put while you pour.
See options on Amazon (opens in a new tab) - Nitrile-coated work glovesBudget price
Wet concrete and mortar are caustic. Keep the cement off your skin with waterproof gloves, and wash off any that gets in.
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Frequently asked questions
How many 8×20 sheets of wire mesh for a 20×20 slab?
3 pieces, lapped 8 inches, weighing 94 pounds in W1.4.
How many 5×10 sheets of wire mesh for a 20×20 slab?
15 pieces with 8 inch laps.
How much wire mesh for a 10×10 slab?
3 pieces of the 5 × 10 ft size, lapped 8 inches.
Sources
- Insteel — Welded wire reinforcement reference information (opens in a new tab) — 6×6 W1.4/W1.4 in 5×150 ft rolls (149.81 lb) and 8×20, 8×15, 8×12.5 and 5×10 ft sheets; 6×6 W2.9/W2.9 in 5×150 rolls and the same sheets.
- American Society of Concrete Contractors — WWR lap splice requirements (hotline Q&A, citing ACI 439.5R-18 §6.4) (opens in a new tab) — Plain-wire welded wire lap splice: one square plus 2 in — 8 in for 6×6 mesh.
- Insteel — Welded wire reinforcement (opens in a new tab) — Standard WWR conforms to ASTM A1064; wire sizes W1.4 to W/D4.