MgO board thickness is the first thing to get right when you specify a Magnesium Oxide (MgO) board. Get the thickness right and you have a fire-rated, waterproof board that outlasts cement board, gypsum and plywood; get it wrong and you either overspend or under-build. This guide walks you through every MgO board thickness in the Wedge WEMAG-S 1000 range — from 4 mm ceiling linings to 25 mm structural subfloor — with indicative 2026 prices and the applications each is built for.
What is an MgO board — and why chloride-free matters
MgO board is a mineral building board made from magnesium oxide, reinforced with fibreglass mesh. It is A1 non-combustible (withstands ~1200°C), waterproof, mould-resistant and rated for 30+ years of service. It will not rot, warp, swell or delaminate — which is why it has replaced plywood and gypsum across partitions, cladding, wet areas and prefab panels.
But not all MgO board is equal. Cheap boards made with magnesium chloride (MgCl₂) absorb humidity and “sweat” — droplets form on the surface, fasteners corrode and boards crack within a few years. Every Wedge WEMAG-S 1000 board is chloride-free, made with magnesium sulphate (MgSO₄), which is far less hygroscopic. The result: no sweating, no fastener corrosion, and a genuine 30+ year service life.
MgO board thickness & price guide (2026)
All boards are supplied in the standard 2440 × 1220 mm sheet size. Prices below are indicative A+B grade rates per square foot, EXW New Delhi — request a quote for exact rates, grade options and bulk discounts.
| Thickness | Indicative price | Best for |
|---|---|---|
| 4 mm | ₹18.12 / SQF (≈ $0.19) | Ceilings, tile backer, wall linings |
| 5 mm | ₹21.00 / SQF (≈ $0.22) | Ceilings, tile backer, linings |
| 6 mm | ₹23.23 / SQF (≈ $0.24) | Ceilings, tile backer, linings |
| 8 mm | ₹31.12 / SQF (≈ $0.33) | Interior partitions, drylining |
| 9 mm | ₹34.75 / SQF (≈ $0.36) | Interior partitions, drylining |
| 10 mm | ₹37.63 / SQF (≈ $0.39) | Fire partitions, cladding substrate |
| 12 mm | ₹43.85 / SQF (≈ $0.46) | Fire-rated walls, external sheathing |
| 14 mm | ₹51.47 / SQF (≈ $0.54) | Heavy-duty walls, subfloor |
| 15 mm | ₹54.26 / SQF (≈ $0.57) | Heavy-duty walls, subfloor |
| 16 mm | ₹56.48 / SQF (≈ $0.59) | Heavy-duty walls, subfloor |
| 18 mm | ₹66.98 / SQF (≈ $0.70) | Structural subfloor, decking |
| 20 mm | ₹74.60 / SQF (≈ $0.78) | Structural flooring, high-load |
| 25 mm | ₹94.48 / SQF (≈ $0.99) | Structural subfloor, roof decking |
USD shown at ~₹95.3 = $1; confirm against the day’s rate. Final price varies with grade, dimensions, edge profile and order quantity.
Which MgO board thickness do I need?
4–6 mm — ceilings, tile backer & linings
The thin end of the range. Use 4, 5 or 6 mm boards for false ceilings, as a tile backer board behind bathroom and kitchen tiling, and for lightweight wall linings where fire and moisture resistance matter but structural load does not.
8–9 mm — interior partitions & drylining
The workhorse thicknesses for internal walls. An 8 mm or 9 mm board gives you a strong, fire-rated, dead-flat drylining surface for offices, homes, basements and shaft linings — lighter and less brittle than cement board.
10–12 mm — fire-rated partitions & cladding
Step up to 10 mm or 12 mm for one-hour fire-rated partition walls, external wall sheathing and as a substrate behind ventilated facades and cladding. This is the range most commercial fire-compliance specs call for.
14–16 mm — heavy-duty walls & subfloor
When you need extra rigidity and impact resistance — heavy-duty partitions, industrial walls, or a base layer for flooring — 14, 15 and 16 mm boards deliver it without the weight penalty of concrete.
18–25 mm — structural subfloor, decking & high-load flooring
The structural end. Use 18, 20 or 25 mm boards as a standalone subfloor under tile, SPC/LVT and vinyl, for roof decking, and in high-traffic or high-load floors. For tiled floors, 18–25 mm gives maximum rigidity as a single structural layer.
MgO board vs cement board, gypsum & plywood
Compared with the alternatives, chloride-free MgO board wins on the combination that matters most for modern construction — fire, water and weight together:
| Property | Wedge MgO | Cement board | Gypsum | Plywood |
|---|---|---|---|---|
| Fire rating | A1, 1200°C | Non-combustible | Limited | Combustible |
| Water resistance | Excellent | Excellent | Poor | Warps |
| Weight | Light | Heavy, brittle | Light | Light |
| Strength | High | High | Low | Medium |
Applications at a glance
Wedge WEMAG-S 1000 boards suit residential, commercial and industrial projects: fire-rated partitions and ceilings, weatherproof exterior cladding and sheathing, wet-area tile backer board for bathrooms, kitchens and pools, MgO subfloor and roof underlayment, and prefab / modular construction including SIP panels, container homes, cold-storage rooms and portable cabins.
How to order
Wedge Industries is a manufacturer and exporter of chloride-free MgO board, supplied across India and export-ready to 45+ countries. Boards are stocked in all 13 thicknesses in the standard 2440 × 1220 mm size, with cut-to-size and edge-profile options on request. Minimum order quantities and container pricing apply for bulk and export orders.
Not sure which thickness fits your project? Send us the application and we’ll recommend the right board and give you today’s best price. Request a quote »