Steel Mesh Selection Guide: A-Series and B-Series UK
Steel Mesh Selection Guide: A-Series and B-Series
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A142 for paths, A193 for slabs, A252 for driveways. A-series vs B-series specs, prices, and which mesh for each job. 020 8079 7719.
| Mesh Type | Wire Diameter | Spacing | Steel Area (cm²/m) | Sheet Size | Weight per Sheet | NDS Price |
|---|---|---|---|---|---|---|
| A142 | 6 mm | 200 × 200 mm | 1.42 | 3.6 × 2 m (7.2 m²) | 10.9 kg | £18.90 |
| A193 | 7 mm | 200 × 200 mm | 1.93 | 3.6 × 2 m (7.2 m²) | 14.2 kg | £26.00 |
| A252 | 8 mm | 200 × 200 mm | 2.52 | 3.6 × 2 m (7.2 m²) | 18.5 kg | £34.37 |
| A393 | 10 mm | 200 × 200 mm | 3.93 | 3.6 × 2 m (7.2 m²) | 28.8 kg | £42.98 |
| Mesh Type | Main Wire | Cross Wire | Main Steel Area (cm²/m) | Cross Steel Area (cm²/m) | Typical Use |
|---|---|---|---|---|---|
| B1131 | 12 mm @ 100 mm | 8 mm @ 200 mm | 11.31 | 2.52 | Suspended slabs, heavy-duty floors |
| B785 | 10 mm @ 100 mm | 8 mm @ 200 mm | 7.85 | 2.52 | Raft foundations, transfer slabs |
| B503 | 8 mm @ 100 mm | 8 mm @ 200 mm | 5.03 | 2.52 | Retaining walls, thick slabs |
| B385 | 10 mm @ 200 mm | 6 mm @ 200 mm | 3.85 | 1.42 | Walls, precast panels |
| B283 | 7 mm @ 100 mm | 7 mm @ 200 mm | 2.83 | 1.93 | Toppings, screeds, thin sections |
| Application | Recommended Mesh | Steel Area Provided | Why This Type |
|---|---|---|---|
| Garden path | A142 | 1.42 cm²/m | Light foot traffic, no vehicle loads, minimum reinforcement |
| Patio | A142 or A193 | 1.42–1.93 cm²/m | Foot traffic, garden furniture, prevents cracking |
| House extension slab | A193 | 1.93 cm²/m | Standard domestic ground-bearing slab, uniform loading |
| Garage floor | A193 | 1.93 cm²/m | Single car, domestic loading, ground-bearing |
| Driveway | A252 | 2.52 cm²/m | Regular vehicle traffic, heavier point loads from wheels |
| Commercial floor slab | A393 | 3.93 cm²/m | Forklift traffic, racking loads, higher design loads |
| Suspended first-floor slab | A393 or B1131 | 3.93–11.31 cm²/m | Spans between supports, needs flexural steel |
| Retaining wall face | B503 or B385 | 3.85–5.03 cm²/m | High steel area in one direction for bending resistance |
| Mesh Type | Sheet Price | Sheet Area | Cost per m² | Cost for 20 m² Slab |
|---|---|---|---|---|
| A142 | £18.90 | 7.2 m² | £2.63/m² | £52.50 (3 sheets) |
| A193 | £26.00 | 7.2 m² | £3.61/m² | £78.00 (3 sheets) |
| A252 | £34.37 | 7.2 m² | £4.77/m² | £103.11 (3 sheets) |
| A393 | £42.98 | 7.2 m² | £5.97/m² | £128.94 (3 sheets) |
What Is A-Series Mesh and When Do You Use It?
A-series mesh has equal steel area in both directions. The wires run at 200 mm spacing both ways, forming a square grid. A142 uses 6 mm wire (1.42 cm²/m), A193 uses 7 mm (1.93 cm²/m), A252 uses 8 mm (2.52 cm²/m), and A393 uses 10 mm (3.93 cm²/m). The number after “A” is the steel area in cm²/m × 100.
Use A-series for flat, ground-bearing elements where loading comes from all directions equally: slabs, paths, patios, driveways. The equal two-way reinforcement handles loads that could arrive from any direction — a car wheel on a driveway, furniture legs on a patio, footfall on a path.
A193 is the UK default for domestic house slabs. It provides 1.93 cm²/m of steel in each direction, which meets the structural requirement for most ground-bearing slabs on compacted fill. One sheet covers 7.2 m² at £26.00. For a 20 m² extension slab, 3 sheets (£78) covers the area with lapping.
What Is B-Series Mesh and How Does It Differ from A-Series?
B-series mesh has unequal steel areas: more steel in the main direction, less in the cross direction. B1131 gives 11.31 cm²/m in the main direction but only 2.52 cm²/m across. This matches structural elements where bending happens primarily in one direction — walls, one-way spanning slabs, and panels.
A retaining wall bends under earth pressure in one direction. B503 provides 5.03 cm²/m in the main direction (horizontal, resisting earth pressure) and 2.52 cm²/m vertically for crack control. Using A-series here wastes steel in the direction that does not need it.
B-series designation: the number is main wire steel area × 100. B785 gives 7.85 cm²/m from 10 mm wires at 100 mm centres. The cross wires (8 mm at 200 mm) provide 2.52 cm²/m for distribution. All B-series uses 200 mm cross-wire spacing. The main wire spacing varies: 100 mm for B1131, B785, B503, and B283; 200 mm for B385. All mesh is B500A to BS 4483:2025.
How Do You Choose the Right Mesh Type for Your Project?
Start with the engineer’s specification. The structural drawing states the mesh type, and that is what you order. If the drawing says A193, order A193 — not A252 “to be safe.” Over-specifying wastes money. Under-specifying fails Building Control.
If you are doing a domestic job without an engineer (path, patio, non-structural slab), use steel area as your guide. Light foot traffic: A142 (1.42 cm²/m). Domestic slab or garage: A193 (1.93 cm²/m). Vehicle traffic: A252 (2.52 cm²/m). Heavy commercial loading: A393 (3.93 cm²/m).
For structural work (suspended slabs, retaining walls, foundations), the engineer specifies the reinforcement. They calculate the bending moment, shear force, and crack width, then select the mesh type that provides the required steel area. If the calculation calls for 3.5 cm²/m in one direction and 1.5 cm²/m in the other, B385 (3.85/1.42) is a closer match than A393 (3.93/3.93). Less waste, lower cost.
What Are the Most Common Mesh Selection Mistakes?
Using A142 where A193 is needed. A142 gives 1.42 cm²/m — 26% less steel than A193’s 1.93 cm²/m. On a domestic slab, this under-reinforcement causes wider cracks under loading. The saving is £7.10 per sheet (£18.90 vs £26.00). On a 30 m² slab needing 5 sheets, you save £35.50 but risk cracking that costs £500+ to repair.
Using A-series for one-way spanning slabs. If the slab spans 4 m between beams and is continuous in the other direction, the engineer needs high steel area across the span and low steel area along the span. A393 provides 3.93 cm²/m in both directions — doubling the steel needed along the span. B785 provides 7.85 cm²/m across the span and 2.52 cm²/m along it, costing less and providing exactly what the structure needs.
Cutting mesh on site to fit rather than ordering the right size. Standard sheets are 3.6 × 2 m. NextDaySteel supplies non-standard sizes on request. Cutting mesh weakens the edge wires and generates 10–15% waste.
How Do You Calculate How Many Mesh Sheets to Order?
Divide the slab area by the net sheet area (allowing for laps). Each sheet is 3.6 × 2 m = 7.2 m² gross. With 150 mm minimum lap on all edges, the net coverage per sheet drops to approximately 6.3 m². Use net area for quantity calculations, not gross.
For a 40 m² slab: 40 ÷ 6.3 = 6.35, round up to 7 sheets. At A193 pricing (£26.00/sheet), that is £182 for the mesh. Add 1 extra sheet for cuts and waste: 8 sheets total at £208. The mesh cost for a 40 m² domestic slab is under £210.
For double-mat reinforcement (top and bottom mesh, used in suspended slabs), double the quantity. A 40 m² suspended slab with A393 top and bottom: 14 sheets at £42.98 = £601.72. Add cut-and-bent edge bars and spacers from the bending schedule. Order mesh and rebar together from NextDaySteel — one delivery at £90 covers everything. Call 020 8079 7719 with your slab dimensions for a quick quantity check.
Mesh Quantity Calculator
Sheets required = slab area ÷ net sheet coverage (6.3 m²) + 1 spare| Feature | A-Series | B-Series |
|---|---|---|
| Wire spacing | 200 × 200 mm (equal both ways) | 100–200 mm main, 200 mm cross |
| Steel area pattern | Equal in both directions | Higher in main direction |
| Typical application | Ground-bearing slabs, paths, driveways | Walls, one-way slabs, structural panels |
| Highest steel area | 3.93 cm²/m (A393) | 11.31 cm²/m (B1131) |
| Stock availability | All types ex-stock, same-day despatch | Available with short lead times |
| When to use | Loading from any direction | Bending primarily in one direction |
Frequently Asked Questions
What is the difference between A-series and B-series mesh?
A-series has equal steel area in both directions (square grid at 200 mm spacing). B-series has more steel in the main direction than the cross direction. Use A-series for ground-bearing slabs, paths, and driveways where loads come from any direction. Use B-series for walls, one-way spanning slabs, and structural elements where bending is primarily in one direction.
Which mesh do I need for a house extension slab?
A193 is the standard specification for domestic ground-bearing slabs. It provides 1.93 cm²/m of steel in each direction using 7 mm wire at 200 mm centres. One sheet costs £26.00 and covers 7.2 m². For a typical 20 m² extension, 4 sheets (£104) covers the slab with lapping. If the slab is suspended (not ground-bearing), the engineer specifies the mesh — often A393 or B-series.
Can I use A252 instead of A193 for a stronger slab?
Only if the engineer approves. A252 provides 2.52 cm²/m versus A193’s 1.93 cm²/m — 31% more steel. More steel does not always mean stronger: the slab thickness, concrete grade, and subbase preparation matter more for a ground-bearing slab. Over-specifying wastes £8.37 per sheet (£34.37 vs £26.00). On a 40 m² slab needing 8 sheets, that is £66.96 wasted.
What mesh is best for a driveway?
A252 for driveways with regular vehicle traffic. A252 has 8 mm wires giving 2.52 cm²/m, 31% more steel than A193. For a light-use driveway (one car, occasional use), A193 may be sufficient. For HGV access or regular heavy vehicle use, check with your engineer — A393 or rebar may be needed. A252 costs £34.37 per sheet (£4.77/m²), versus A193 at £26.00 (£3.61/m²).
How do I know if I need B-series mesh?
If the structural drawing shows different steel areas in each direction, you need B-series. A wall needing 5 cm²/m horizontally and 2.5 cm²/m vertically suits B503 (5.03/2.52). If the drawing shows equal steel in both directions, use A-series. B-series is specified by engineers for structural elements — you would not normally choose B-series for domestic ground-bearing slabs.
Does NextDaySteel stock all mesh types?
All A-series (A142, A193, A252, A393) ship from stock as same-day despatch items. Standard sheet size is 3.6 × 2 m. B-series (B1131, B785, B503, B385, B283) is available with short lead times. All mesh is B500A grade to BS 4483:2025, CARES certified. Order before 1pm for next-day delivery (£90) or choose economy delivery (£30, 2–4 working days). Call 020 8079 7719.
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