Pyrotite® — your protection
Every second counts
OSB Firestop is an OSB/3 structural core finished with a patented Pyrotite® coating. According to the European classification (EN 13501-1) it meets reaction-to-fire class B-s1, d0. The Pyrotite® finish is made of fireproof materials based on magnesium oxide, reinforced with a fibreglass mesh — keeping the load-bearing performance of OSB/3 while buying critical time in a fire.
How Pyrotite® protects
Best wood-based fire class
The Pyrotite® face reaches reaction-to-fire class B-s1, d0 (EN 13501-1) — the highest practical class for a wood-based board.
Water that fights fire
Up to 2 litres of crystal-bound water per 2.5 × 1.25 m board is released as vapour above ~100 °C, cooling the surface and slowing burn-through.
Stronger, not just safer
The fibreglass-reinforced Pyrotite® layer raises bending and shear strength while the OSB/3 core keeps its full structural load capacity.
Faster than drywall
Lighter, single-step assembly, formaldehyde-free binders and 15+ years of proven use — with no hazardous emissions, even under fire.
Tested building systems
Labelled cross-section · OSB Firestop highlighted
External & interior
Walls
OSB Firestop is the load-bearing inner face of timber-frame walls. As a B-s1, d0 final lining it is fixed in one step — replacing the usual two layers of OSB plus plasterboard — while keeping the full load capacity of OSB/3.
- Fire REI 30 · 45 · 60
- Sound Rw ≥ 45–50 dB
- Load ≤ 32 kN/m
- External wall
- Single-step interior cladding in ventilated-facade or ETICS build-ups. T&G boards glued with PU; vapour-permeable layers run behind the board.
- Interior wall
- Single-layer cladding both sides of a timber frame — enough for load-bearing partitions in two-storey timber buildings. Battens add an installation gap for wiring.
| Recommended board | OSB Firestop 16 mm (T&G, PU-glued joints) |
|---|---|
| Fire resistance | REI 30 · 45 · 60 (+ REW) |
| Airborne sound Rw | ≥ 45–50 dB |
| Thermal U-value | from 0.11 W/(m²·K) — ETICS build-ups |
| Max. vertical load | 32 kN/m |
| Tested systems | Ventilated facade · ETICS (EPS-F / mineral wool) · interior partition |
| Classification | PKO-23-081 · external walls interior→exterior, interior walls one side |
Labelled cross-section · OSB Firestop highlighted
Floors & roofs
Decking
Visible structural decking carried on exposed beams — the modern interior look. A single layer of OSB Firestop becomes the deck, finished and installed fast, for floors and flat or pitched roofs.
- Floor REI 60
- Roof REI 20–45
- Sound Rw ≥ 57–61 dB
- Floor decking
- Exposed-beam floors and lofts; impact sound Ln,w down to ≤ 53 dB with the modern open-ceiling look.
- Roof decking
- Flat and pitched roofs on exposed beams or rafters, forming part of the tested roof system.
| Recommended board | OSB Firestop deck — 31 mm (floor) · 23 mm (flat roof) · 19 mm (pitched roof) |
|---|---|
| Fire resistance | Floor REI 60 · flat roof REI 20–45 · pitched roof REI 30 |
| Airborne sound Rw | ≥ 57–61 dB (floor) |
| Impact sound Ln,w | ≤ 53–58 dB (floor) |
| Beams / rafters | 140/180 @ ≤ 833 mm (floor & flat roof) · 100/200 @ 625 mm (pitched) |
| Span | up to ≈ 5 m (floor) — see load–span charts |
| Classification | PKO-23-082 · ceilings & roofs from below |
Labelled cross-section · OSB Firestop highlighted
Soffit lining
Ceiling
Used as the ceiling soffit, OSB Firestop is a finished, impact-resistant, non-flammable underside that doubles as the fire barrier — no separate plasterboard ceiling needed.
- Fire REI 30
- Sound Rw ≥ 54–56 dB
- Impact Ln,w ≤ 61 dB
- Where it suits
- Offices, workshop halls and storage buildings — a robust, paintable ceiling that resists knocks far better than drywall.
| Recommended board | OSB Firestop soffit — 16 mm |
|---|---|
| Fire resistance | REI 30 |
| Airborne sound Rw | ≥ 54–56 dB |
| Impact sound Ln,w | ≤ 59–61 dB |
| Structure | Timber beams 80/200 @ 625 mm · MW insulation 200 mm |
| Best for | Offices, workshop halls and storage buildings |
| Classification | PKO-23-082 · ceilings & roofs from below |
Fire resistance is declared for the complete tested assembly — external walls classified interior→exterior, interior walls from one side, ceilings and roofs from below (plus REW for walls). Classification reports PKO-23-081 (walls) and PKO-23-082 (ceilings & roofs) cover 34 structures to EN 13501-2.
The Firestop family
Technical documents
Fire-resistance ratings belong to the complete tested assembly — see the classification report for declared values and conditions.