Fire protection · Stone wool
ROCKWOOL Rocksafe Plus
- Thickness
- 135 mm
- Density
- 80 kg/m³
- Thermal conductivity (λ)
- 0.035 W/m·K
How is stone wool used in passive fire protection (fire stopping / curtain-wall safing)?
In short
Passive fire protection divides a building into fire compartments and seals the weak points — joints, service penetrations and the gap between a curtain wall and the floor edge — so fire and smoke cannot pass. Non-combustible stone wool is used as part of the systems that seal these gaps, but the fire-resistance rating belongs to the tested system and depends on thickness, density, compression, fixing and the surrounding construction. It must be installed to the tested details by qualified installers and approved under local requirements.
- 1Tests the material itself: how easily it ignites, how far flame spreads, smoke and burning droplets — then classifies it, for example under EN 13501-1. 'Non-combustible' is a result of this kind of test
- 2Smoke and droplets are part of the classification
- 3Tests the complete wall, floor or fire-stopping system on a furnace, built as it will be installed
- 4The result is how long it keeps meeting the criteria (for example 60 or 120 minutes) — it belongs to that system, not to one material
The principle: compartmentation
Walls and floors designated as fire-separating help confine fire, heat and smoke to the room of origin, giving occupants time to escape and fire services time to respond. But a fire wall or floor only works if it has no gaps. Typical problem spots are:
- Openings where pipes, cables, cable trays or ducts pass through walls and floors (penetrations)
- Joints between walls and floors or ceilings (linear joints)
- The gap between the floor edge and the curtain wall (perimeter void), a path for fire to climb from one floor to the next
What does stone wool do in the system?
- It is a non-combustible filler, compressed into the gap to block flames and hot gases
- It is usually combined with other system components, such as support brackets or framing, fire-rated coatings or sealants and facings, as the tested system specifies
- Different stone-wool products are designed for different jobs, e.g. ROCKWOOL Rocksafe Plus for the curtain-wall/floor-edge gap and ROCKWOOL Conlit H110, which the maker describes as used as part of fire-protection systems
"Non-combustible" is a property of the slab; "how many minutes" is a result of the system. See reaction to fire, non-combustible and fire resistance.
Example: curtain-wall safing
Curtain walls are generally not designed as fire walls, so the gap between the concrete floor edge and the curtain wall must be sealed with a tested system.
ROCKWOOL reports a fire-resistance result to BS 476 Part 20 for Rocksafe Plus in a tested installation: 135 mm slabs compressed by at least 15% of their width, fitted into openings in a concrete floor slab. This is not a property of the slab on its own. If site conditions differ from the test — a wider gap, less compression or different construction — the manufacturer or an engineer must assess it.
Elsewhere, perimeter fire containment systems have their own test standards, such as ASTM E2307 in North America. For projects in Thailand, check which test standards the designer and local authority accept.
What affects the fire-resistance result?
| Factor | Why it matters |
|---|---|
| --- | --- |
| Stone-wool thickness and density | Must match what was tested |
| Compression | Too little can open gaps when the structure moves or heats up |
| Fixing and support | The stone wool must stay in place throughout a fire |
| Gap size and building movement | Systems are tested for set gap widths and movement ranges |
| Sealants, coatings and surrounding materials | Part of the system; substitutes may not be covered by the test |
| Position and orientation | Horizontal and vertical are tested separately |
Safety and approval
- Do not pick stone wool by density or the word "non-combustible" and install it yourself. Fire protection needs a tested system installed to its details
- Have a fire-safety engineer or designer specify the system, and qualified installers fit it
- Manufacturers advise checking local-authority approvals; requirements depend on building-control law and building type
- Keep test reports, installation details and photos taken before covering up, for inspection and handover
- When new openings are made in walls or floors later, seal them with a tested system
Common mistakes
- Claiming a stone-wool slab is "2-hour fire-rated" without naming the tested system
- Using general acoustic or thermal stone wool instead of the product used in the tested system
- Cutting slabs to fit exactly without the required compression, or without fixings
- Filling the gap with stone wool but leaving out the sealant or coating the system requires
Sources
- ROCKWOOL (Thailand) — Rocksafe Plus Data Sheet (300 301-11/20 V4)
- ROCKWOOL (Thailand) — Conlit Data Sheet (300 319-07/22 V3)
- ROCKWOOL North America — Perimeter Fire Containment System Technical Guide (Curtain wall systems)
- ROCKWOOL Asia — Fire resistance (Fire resilience)
- BS 476 Part 20 — Method for determination of the fire resistance of elements of construction (general principles)
- ASTM E2307 — Fire resistance of perimeter fire barriers (title only)
- EN 13501-2 — Fire classification: fire resistance tests
Related products
Categories and example products for this topic
- ROCKWOOL Rocksafe Plus — 135 mm stone wool sealing the curtain-wall / floor-edge gap; fire result is the system's
- ROCKWOOL Conlit H110 — Specially formulated 110 kg/m³ stone wool used as part of passive fire-protection systems
Fire protection · Stone wool
ROCKWOOL Conlit H110
- Thickness
- 25–100 mm
- Density
- 110 kg/m³
- Thermal conductivity (λ)
- 0.039 W/m·K