Product

Typical Construction

The exposed surfaces of any steel section are fully enclosed in Rocksilk FireTech Slab, using any of the fixing systems shown on above. Rocksilk FireTech Slab can be used to provide up to 4 hours fire protection to structural steel and cast iron columns, beams and trusses.

Steel sections may include universal beams, columns and joists (plain and castellated), structural and rolled tees, angles, channels and round, square or rectangular hollow sections.

Installation

Rocksilk FireTech Slab can be used with four types of fixing systems for the fire protection of structural steelwork. They are:

• Dry Fix System
• Noggin Fixing System
• Combination Fixing System
• Welded Pin Fixing System.

Each system has its own performance characteristics:

1. The Dry Fix Noggin System is a fast and efficient push fit noggin system that does not need glue. It can give up to 2 hours fire protection to BS 476: Part 21. When installing 20, 25 and 30mm FireTech Slab a 30mm noggin board should be used. When greater thicknesses of FireTech Slab are used, the corresponding thickness of noggin board should be used.
2. The Adhesive Noggin Fixing System can be used to provide up to 2 hours fire protection to all sizes of structural steelwork.
3. The Combination Fixing System can be used to provide up to 2 hours fire protection to all sizes of structural steelwork, and up to 3 hours fire protection to steelwork with section factors (Hp/A) of up to 133m^-1 for columns and 143m^-1 for beams.
4. The Welded Pin Fixing System can be used to provide up to 3 hours fire protection to all sizes of structural steelwork, and up to 4 hours fire protection to steelwork with section factors (Hp/A) of up to 172m^-1 for columns and 184m^-1 for beams.
5. If section factors are above 260m^-1 contact our Technical Advisory Service. For castellated beams work out thickness as normal then add 20% to thickness. The use of a dense mineral wool board requires no special vee cuts, drilling or sub-frames, making it fast and easy to install. Mineral wool slabs can be easily cut using hand or power tools. For more detailed information about fixing Rocksilk FireTech Slab, please see below. Note: Rocksilk Dry Fix Noggin Board has a density of 200 kg/m³.

Screw detail

Screw length and board thickness

The spirally wound or Pig Tail Screws are made from 16 gauge galvanised wire and are available from stockists. A specification is available on request from our Technical Advisory Service.

The screws should be installed flush at 150mm centres on board to board joints and 100mm centres over noggins, using either power or hand tools. There is no need to countersink screw heads. For the various board thicknesses, screw length should be in accordance with the table below.

Noggin detail

Noggins are cut 100mm wide from 20mm thick Rocksilk Firetech Slab. They should be cut to a suitable length relative to the web size to give a tight fit. Noggins are glued top and bottom using a typical adhesive thickness of 0.5mm and push fitted between the flanges at 600mm centres.

The noggins should be installed in such a way that they are slightly 'proud' of the flange (by about 2mm) and such that they coincide with joints between the boards. It is preferable to leave the noggins in position for 4 hours to allow the adhesive to cure. However, where this is impractical Rocksilk Firetech Slab can still be fitted before the adhesive cures since the noggins are essentially friction fitted.

For web depths greater than 500mm, T-shaped or solid noggins should be used, formed from Rocksilk Firetech Slab, and screwed together using Pig Tail Screws.

Adhesive detail

Rocksilk Firetech Adhesive* can be used straight from the container without stirring at ambient temperatures down to -10ºC. No special accelerators need to be added though cure times will be longer at such cold temperatures (but will still set within 24 hours).

Steelwork should ideally be dry but the presence of condensation will merely prolong the cure time not weaken the bond strength. The bond strength will not be weakened if temperatures lower than -10ºC are experienced before the adhesive has set. Since only the top and bottom surface of each noggin is glued with a typical adhesive thickness of 0.5mm, excellent rates of usage are achievable.

Rocksilk Firetech Adhesive is available from stockists of Rocksilk Firetech Slab. Note: Steelwork should be clean and free from grease prior to the application of Rocksilk Firetech Adhesive.

*For further details contact our Insulation Academy Technical Advisory Centre.

Performance

Standards

Rocksilk Firetech Slab is non-combustible inorganic rock wool, defined as mineral wool in BS 3533:1981 and is manufactured in accordance with BSI Quality Assurance Standard BS EN ISO 9002: 1994.

Operating temperatures

Rocksilk Firetech Slab can be used up to a continuous operating temperature of 850ºC.

Fire performance

Rocksilk Firetech Slab is classified as noncombustible to BS 476: Part 4: 1970 (1984), Class 1 surface spread of flame to BS 476: Part 7: 1997, and Class ‘O’ to the Building Regulations and is A1 to Euroclass when unfaced.

Rocksilk Firetech Slab is designed to provide up to 4 hours fire protection to structural steelwork, thereby satisfying the current Building Regulations and insurance demands for periods of fire resistance.

Permanence

Rocksilk Firetech Slab is rot proof, does not sustain vermin and will not encourage the growth of fungi, mould or bacteria. Rocksilk Firetech Slab is odourless and non-hygroscopic. Rocksilk Firetech Slab is non-wicking when tested to BS 2972: 1989: Section 12. When exposed to 90% relative humidity and 20ºC, Rocksilk Firetech Slab absorbs less than 0.004% of moisture.