How many layers of plasterboard for a 1-hour fire rating?

For a 60-minute (FD60) fire rating, you typically need two layers of 12.5mm Gyproc Fireline plasterboard on each side of a steel or timber stud partition. This gives a total board thickness of 25mm per side. Some systems achieve 60 minutes with a single 15mm Fireline board, but the double-layer 12.5mm system is more common in UK commercial fit-outs.

What screws do I need for fire-rated plasterboard?

For fire-rated systems, you must use the correct length drywall screws. For a single 12.5mm layer, use 25mm screws. For double layers, the first layer uses 25mm screws and the second layer uses 42mm or 45mm screws to penetrate through both boards into the stud. Screws must be at 200-300mm centres depending on the tested system specification. Always check the manufacturer's installation guide.

Do I need special tape for fire-rated joints?

Standard paper joint tape is acceptable for most fire-rated plasterboard systems. The joints should be taped and filled with appropriate jointing compound (not self-adhesive mesh tape, which is not suitable for fire-rated joints). The key is ensuring all joints are properly sealed with no gaps, as the tape and compound help maintain the fire barrier at the board joints.

What is the difference between Fireline and standard plasterboard?

Gyproc Fireline (pink board) contains glass fibre and vermiculite additives that improve fire resistance. A single 12.5mm Fireline board achieves 30 minutes fire resistance, compared to approximately 20 minutes for standard wallboard. For rated fire partitions (FD30+), you must use Fireline or equivalent fire-rated boards — standard plasterboard alone will not achieve the required rating.

Do both sides of a fire partition need fire-rated board?

Yes — for a fire partition to achieve its rated performance, both sides must be boarded to the tested specification. An FD60 partition typically needs 2 × 12.5mm Fireline on each side (4 layers total). Our calculator covers one side — double the quantities if you are boarding both sides of a new partition.

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Fire Rated Plasterboard Calculator — FD30 to FD120 Systems

Calculate board layers, screws, joint tape, and compound for fire-rated partition and wall lining systems to BS 476 / EN 1364-1.

Wall Area (one side)

Total area to be boarded on one side

Fire Rating Required

Based on BS 476 / EN 1364-1 tested systems

Stud Centres

Typically 300mm for fire-rated, 600mm standard

Price Per Board (optional)

Per sheet of Fireline plasterboard

How We Calculate This

This calculator determines the number of fire-rated plasterboard sheets, screws, joint tape, and compound needed for your chosen fire rating. It uses tested system specifications from British Gypsum (Gyproc Fireline range) aligned with BS 476 and EN 1364-1 fire test standards.

The formula

Total boards = (Wall area ÷ Board area) × Number of layers × Wastage factor

Screws are calculated per board based on perimeter fixings at your chosen spacing, plus intermediate stud fixings. Joint tape is estimated at 1.8m per m² of finished wall area (accounting for horizontal and vertical joints). Compound is estimated at 0.4 kg/m².

Layer configurations

FD30: 1 × 12.5mm Fireline (one side)
FD60: 2 × 12.5mm Fireline (one side)
FD90: 2 × 15mm Fireline (one side)
FD120: 3 × 12.5mm Fireline (one side)

These are per-side quantities. For a complete partition, you need the same build-up on both sides.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.