Key points
- EN 520: type A standard, H reduced water absorption (H1 ≤ 5%, H2 ≤ 10%, H3 ≤ 25%), F improved core cohesion at high temperature, I enhanced surface hardness, R enhanced strength.
- All moisture-resistant boards sold by the major UK manufacturers are class H1.
- Moisture-resistant board is not waterproof; US tile council guidance rules it out as a direct tile backing in wet areas, so in a shower the safer choice is cement board with waterproofing.
- In the US system: Type X is a fire-resistant board under ASTM C1396, and the fire rating belongs to the whole listed assembly.
Gypsum board (plasterboard) is widely used for suspended ceilings and interior partitions. The wrong type in a bathroom or kitchen means swelling and mould; elsewhere it can mean weak fire resistance.
1) Board types under EN 520
The European standard EN 520 defines board types by letters (the typical-use column is practical guidance from this encyclopedia)1:
| Type | Description | Typical use |
|---|---|---|
| A | Standard board for gypsum plaster or decoration. | Dry interior walls and ceilings. |
| D | Controlled density. | Where specific acoustic or mechanical performance is required. |
| E | Sheathing board for external walls; low water absorption, not permanently exposed to weather. | Sheathing behind facades. |
| F | Mineral fibres and additives improving core cohesion at high temperature. | Fire-resistant systems. |
| H (H1/H2/H3) | Reduced water absorption. | Kitchens and bathrooms outside direct spray. |
| I | Enhanced surface hardness. | Corridors and impact-prone areas. |
| P | Base board for gypsum plaster. | Plaster base. |
| R | Enhanced longitudinal and transverse strength. | Applications needing higher strength. |
2) Moisture boards (H): the numbers and limits
EN 520 classifies moisture resistance by total water absorption by weight2:
| Class | Total water absorption |
|---|---|
| H1 | ≤ 5% |
| H2 | ≤ 10% |
| H3 | ≤ 25% |
The same source states that all moisture-resistant boards sold by British Gypsum, Knauf and Siniat in the UK are class H12.
3) In the US (ASTM) system
- ASTM C1396 covers gypsum board.
- Type X: fire-resistant board; for example a 5/8-inch (15.9 mm) board complying with ASTM C1396 as Type X and UL Classified for fire resistance, used in the UL Designs that list it; fire ratings belong to the whole assembly, not the board alone4.
- Mould resistance is tested to ASTM D32734.
A "one-hour fire rating" is a property of the whole tested system (board, framing, fasteners and joints), not of the board alone.
4) Suspended ceilings: moisture, openings, lighting and maintenance
Practical tips; suspension systems and their loads are set by the manufacturer's approved system, not by general estimates.
- Moisture: moisture-resistant boards are not waterproof (Section 2); a leak from above (AC, plumbing) shows as stains and sagging. See Leak detection.
- Access hatches: leave a hatch near every concealed AC unit, valve and junction box; a ceiling with no hatches means cutting at the first fault.
- Lighting: recessed downlights need space and ventilation per the manufacturer, and the wiring is licensed electrical work. See Breakers.
- Hanging loads: don't hang a fan or heavy device on the board itself; loads are fixed to the structure per the approved system.
- Cracks: usually at joints or from movement; find the cause before filler and paint. See Paint problems.
5) Quick selection guide
| Location | Common choice |
|---|---|
| Ceilings and partitions in rooms and living areas | Standard board (A) |
| Kitchen and bathroom outside the spray zone | H1 moisture board |
| Inside the shower (spray zone) | Cement board, fibre-cement or compliant glass-mat gypsum board, with waterproofing. See cement board |
| Fire separation (e.g. between garage and house) | F or Type X systems per fire code requirements |
| Impact-prone corridors | Hard-surface board (I) |
Guidance table. Fire requirements are governed by the adopted fire codes and the manufacturer's tested system.
Sources
The number next to a statement points to its source in this list. Sources back the general information; anything marked “practical advice” is editorial experience, not a quoted source. Anything that affects safety, structural design or electrical installations needs a licensed professional, and in Saudi Arabia the binding reference is the Saudi Building Code.
- 1Gypsum plasterboard works — board type definitions under EN 520 — Technical summary of EN 520:2004+A1:2009
- 2Moisture-Resistant Plasterboard (Green Board): When You Need It and When You Don't — BuildWiz UK
- 3TDS 294 — Tile & Stone Backer Board Selection Guide (cement board ASTM C1325, fiber-cement C1288, gypsum limits) — LATICRETE International — technical data sheet
- 4Sheetrock® Mold Tough® Firecode® X Panels — ASTM C1396 Type X, ASTM D3273 — USG