A193 Mesh: Size, Weight and When to Use It (Without Over-Engineering Your Slab)
A193 mesh is the steel grid that turns a plain concrete slab into one that shrugs off cracks. If you've seen "A193" on a drawing or a merchant's price list and wondered what the code actually means, whether you need it, or how many sheets to order, this is the plain-English version.
What does A193 actually mean?
The code isn't random. Under BS 4483 (the UK standard for steel fabric), the letter tells you the pattern and the number tells you how much steel there is:
- A means a square mesh: the bars are the same size both ways, at 200 mm (about 8 in) centres.
- 193 is the cross-sectional area of steel in mm² per metre width. More steel, bigger number.
So A193 is 7 mm bars at 200 × 200 mm centres, giving 193 mm² of steel per metre. Think of it like the thread count on bedsheets: the number on the label tells you how much is packed in, not how big the sheet is.
A193 mesh size and weight
The standard sheet is 4.8 × 2.4 m (about 15 ft 9 in × 7 ft 10 in), which is 11.52 m². Here's how A193 sits against the rest of the A-series:
| Mesh | Bar diameter | Spacing | Weight (kg/m²) | Weight per 4.8 × 2.4 m sheet | Typical use |
|---|---|---|---|---|---|
| A142 | 6 mm | 200 × 200 mm | 2.22 | ≈ 26 kg | Patios, shed bases, car driveways |
| A193 | 7 mm | 200 × 200 mm | 3.02 | ≈ 35 kg | Garage floors, extension slabs, heavier driveways |
| A252 | 8 mm | 200 × 200 mm | 3.95 | ≈ 45 kg | Commercial floors, heavier vehicles |
| A393 | 10 mm | 200 × 200 mm | 6.16 | ≈ 71 kg | Industrial slabs, heavy plant |
At about 35 kg (77 lb) a sheet, A193 is a two-person lift. Carrying it alone across a building site is like moving a mattress in the wind: technically possible, never dignified.
In North America, the nearest equivalent is roughly 6×6 W4.0/W4.0 welded wire reinforcement (6 in squares, about 5.7 mm wire). It's close but not identical, so follow your local spec.
A142 or A193: which do you need?
This is the question everyone actually asks. A short rule of thumb:
- A142 for a shed base, a patio, a path, or a driveway that only sees cars.
- A193 for an extension floor, a garage slab, a driveway that gets vans or the occasional skip lorry, or anywhere the ground is soft or patchy.
A193 has about 36% more steel than A142 for a modest price jump, which is why plenty of builders default to it on anything structural. But if Building Control or an engineer has specified a mesh on the drawing, that's the one you use. Their drawing beats any rule of thumb, including this one.
How many sheets of A193 do I need?
Sheets have to overlap so the steel works as one continuous grid. Laps are typically 200–300 mm (or at least two cross-wires), so each sheet effectively covers nearer 10 m² than its full 11.52 m².
Worked example: a single garage slab 6.0 × 4.0 m (19 ft 8 in × 13 ft 1 in).
- Slab area: 6 × 4 = 24 m².
- Effective cover per sheet, allowing for laps: ≈ 10 m².
- 24 ÷ 10 = 2.4, so order 3 sheets.
- Total weight: 3 × 35 kg ≈ 105 kg. Plan the delivery and the unloading.
Rather than doing the lap maths on the back of a cement bag, the reinforcing mesh calculator works out sheets for any slab size and mesh type, laps included.
Laying A193 properly
Mesh only works if it ends up inside the concrete, at the right height. A sheet lying on the hardcore is about as useful as a seatbelt left in the glovebox.
- Cover: keep at least 40–50 mm (about 2 in) of concrete over the steel, and keep it about 50 mm in from the edges.
- Height: sit it on plastic chairs or spacers, typically in the upper third of a ground-bearing slab for crack control, unless your engineer says otherwise.
- Laps: overlap every joint and tie the sheets with wire so they don't shift when the concrete goes in.
- Cutting: bolt croppers or an angle grinder. Wear eye protection, as the offcuts spring.
- Don't prop it on bricks or broken blocks. They create weak spots and let water track to the steel.
How much concrete goes with it?
The mesh doesn't change the concrete volume. That 6 × 4 m garage slab at 150 mm (6 in) thick is 6 × 4 × 0.15 = 3.6 m³ (about 4.7 yd³) before waste. Run it through the concrete calculator to add a waste allowance and get bags or a ready-mix order.
Frequently asked questions
What size is A193 mesh?
Standard sheets are 4.8 × 2.4 m (11.52 m²), made of 7 mm bars at 200 mm centres both ways. Some merchants also sell smaller 3.6 × 2.0 m sheets for DIY jobs.
How much does a sheet of A193 weigh?
About 3.02 kg per m², so roughly 35 kg (77 lb) for a full 4.8 × 2.4 m sheet.
Is A193 mesh overkill for a driveway?
For cars only on good ground, A142 is usually enough. A193 makes sense if vans, delivery lorries or skips will use it, or the ground is soft.
Can I use A193 in a 100 mm slab?
Yes, as long as you can keep around 40 mm of cover top and bottom. In thin slabs, accurate chairs matter more than the mesh grade.
Do I need mesh at all?
Not every slab does, but mesh controls cracking from shrinkage and settlement. For garage floors and extension slabs it's standard practice, and often specified by Building Control.
Size up your slab in one go
These tools cover the steel, the concrete and the weight of the finished slab:
- Reinforcing Mesh Calculator: sheets of A142, A193, A252 or A393 for any slab, with laps built in.
- Concrete Calculator: volume in m³ or yd³ plus bags or ready-mix for the same slab.
- Concrete Weight Calculator: what the finished slab weighs, handy for suspended or raised bases.