Semi-rigid mineral wool slab

(Density 100kg/m³not less than 25mm thickness)

• Fire resistance (integrity). Joints can compromise fire integrity but generally considered to be excellent. (✩✩✩✩✩)

• Temperature rise (insulation). Well fitted slab of the correct thickness has excellent fire insulation characteristics. (✩✩✩✩✩)

• Smoke resistance. Good because of density but excellent when coated and jointed properly. (✩✩✩✩)

• Contribution to fire growth. Class 0 or limited combustibility.

(✩✩✩✩✩)

• Loading and deflection. Able to accommodate lateral movement, but not as good as quilt in accommodating ‘in-plane’ deflection. (✩✩✩)

• Ability to accommodate services. Semi-rigid mineral wool batts are used extensively as bulk-heads in many penetration systems because of its ability to allow sealants to be used. (✩✩✩✩✩)

• Durability. Impact and environmental both normally considered excellent. (✩✩✩✩✩)

5. STEEL FACED FIBRE REINFORCED CEMENT BOARDS

Strong and robust but has the disadvantage of being heavy and the structure must be able to accept the weight.

FIRE PERFORMANCE DATA

• Fire resistance (integrity). These materials have excellent integrity resistance. (✩✩✩✩✩)

• Temperature rise (insulation). Generally poor and needs to be used with insulation material to achieve ratings. (✩)

• Smoke resistance. Impermeable but joints and edges may require special treatment. (✩✩✩✩✩)

• Contribution to fire growth. Class 0 and non combustible and meets the requirements of Part 2.2 of this Design Guide. (✩✩✩✩✩)

• Loading and deflection. Very strong and able to accept loads and may, when fixed, restrain deflection. Installation method needs to be designed if it is to accommodate deflection. (✩✩✩)

• Ability to accommodate services. Rigid enough to accept sealants around services and stiff enough to provide support and to allow fixing of pipe collars and penetration sealing systems. (✩✩✩✩✩)

• Durability. Excellent, particularly suitable for industrial applications.

(✩✩✩✩✩)

6. VERMICULITE SPRAYED MESH

A supporting wire mesh is installed initially to which a sprayed vermiculite coating is applied. Attention to detail regarding coating thickness and ‘plug holing’ voids should be observed on site post application.

6 Design Guide for the Fire Protection of Buildings

Access needed for spray equipment. More dependent upon quality of application than some alternatives and trained operators required.

Recommended thicknesses should be obtained from the manufacturer FIRE PERFORMANCE DATA

• Fire resistance (integrity). Good when evenly applied and spraying tends to produce good edge sealing. (✩✩✩✩)

• Temperature rise (insulation). Vermiculite has excellent insulation characteristics albeit only as good as the application on site. (✩✩✩✩)

• Smoke resistance. When evenly applied the product should be impermeable and joint free. (✩✩✩✩✩)

• Contribution to fire growth . Generally non-combustible or of limited combustibility. (✩✩✩✩✩)

• Loading and deflection. Able to resist lateral deflection, but needs special design details to accommodate ‘in-plane’ deflection. (✩✩✩)

• Ability to accommodate services. Not able to accept fixings and therefore special provisions need to be made albeit small services can be sealed with sealants .(✩✩)

• Durability. Not immune from damage albeit the basic material is stable in use. (✩✩✩)

7. GLASS FIBRE BASED CURTAINS

These are not recommended for applications in excess of [30] minutes as their ability to protect the property can be low where structure is adversely affected by radiant heat.

FIRE PERFORMANCE DATA

• Fire resistance (integrity). Good up to the stated rating albeit joints need to be correctly made. (✩✩✩✩)

• Temperature rise (insulation). They offer very little insulation and should only be used where the structure adjacent is non combustible. (✩)

• Smoke resistance. When jointed properly the coated fabric is excellent.

(✩✩✩✩✩)

• Contribution to fire growth. Generally Class 0. (✩✩✩✩✩)

• Loading and deflection. Can be fitted to readily accommodate deflection. (✩✩✩✩✩)

• Ability to accommodate services. Poor due to the thinness of the membrane. Special methods are available but trained installers are essential. (✩)

• Durability. Not completely exempt from damage but the materials are stable in use. (✩✩✩✩)

RECOMMENDED THICKNESSES OF MATERIALS

It is not possible to give or recommend a thickness for the various materials as the size of the barrier will often dictate the thickness needed to provide the integrity rating. Even within a generic group, the various products will require

Construction design and data sheets 6

different thicknesses to satisfy the restriction on temperature rise for the appropriate duration.

The manufacturers’ LPCB approval, test evidence and/or Field of Application Report should be referred to when specifying or auditing a cavity barrier installation. Where the robustness of the product is of concern minimum thicknesses are shown in this Data sheet for each generic type of product.

SUMMARY OF PERFORMANCE DATA

Table 1 overleaf summarises the assessed relative abilities of the featured materials to satisfy the identified performance requirements.

INSTALLATION

Cavity barriers are only as good as the structure to which they are attached and the materials used are only as good as the design and quality of the construction of the barrier. When using board materials, double sided partition type barriers are recommended. Where a single sided construction is contemplated for large cavity barriers the structural studs and/or elements of structure to which they are attached shall be fully protected with respect to fire attack from the side opposite to the board (Figure 1a). When using ‘curtain’

type materials these shall be fitted so as to protect their supporting members or be fixed only to existing protected members (Figure 1b). It shall be recognised that pre-fabricated roof members, e.g. metal plate jointed timber trusses, have an inherently low fire resistance and cavity barriers in such roofs should be fixed and act independently of the roof system.

Bracing is present in many roofs. Often this bracing penetrates the cavity barrier. The installation must accommodate any anticipated movement of that brace, either in use or in a fire, taking into account that roof members are rarely fire protected, except when required by Part 5.5 of the Design Guide, and are therefore liable to significant movement. Metal bracing shall be treated like a metal pipe penetration (Data sheet 6.7.1) and timber bracing shall be fire protected for at least 100mm either side of the barrier (see Figure 2).

Where the construction bounding the roof is liable to deflect in a fire the edge fixings or, in the case of flexible barriers, the barrier itself shall be able to accommodate deflections up to L/30. Examples of how this may be achieved are given in Figures 3, 4 and 5.

IMPORTANT NOTE: When fixing cavity barriers to fire protected supporting members it is vital that the fixings do not compromise the protection to the member and in all cases any fire protection removed shall always be made good.

The installation of cavity barriers should be executed and completed by a suitably qualified person to the required standard appropriate to the system used. It is advisable that where fire performance is required then an inspection by an independent body may be carried out on the completed work.

IDENTIFICATION

Any LPCB approved barrier or installation should carry a permanent mark identifying the LPCB approval number. It is recommended that non LPCB approved barriers shall be clearly indelibly marked with the manufacturer’s or installer’s name and a statement of the fire integrity and insulation rating.

6 Design Guide for the Fire Protection of Buildings

Table 1. Summary of data. RequirementsFire resistanceTemperatureSmokeContributionLoadingAccommodatingDurability - Durability -Minimum (integrity)rise resistancetoand servicesimpact environmental thickness (insulation)fire growthdeflectionresistanceconditions Cavity barrier materials 1.Calcium silicate and cement based boards✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩7mm 2.Unreinforced gypsum based boards✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩19mm 3.Reinforced gypsum boards✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩12mm 4.Mineral wool quilt 4.1 Mineral wool quilt (not less than 40mm)✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩40mm 4.2 Semi-rigid mineral wool slab✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩25mm (not less than 25mm) 5.Steel faced fibre reinforced cement boards✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩ 6.Vermiculite sprayed mesh✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩ 7.Glass fibre based curtains✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩✩

Construction design and data sheets 6

Figure 1a. Example of protection to structural members which incorporate the cavity barrier.

Figure 1b. Example of protection to structural member which supports fire resisting curtain.

Figure 2. Timber bracing shall be fire protected for at least 100mm either side of the barrier.

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Wall/roof lining

Applied fire protection

Roof truss member

Cavity barrier

Wall/roof lining

Fire resisting curtain

Service peneration

Protection to penetration

Cavity barrier

Bracing member

min. 100mm

min. 100mm

6 Design Guide for the Fire Protection of Buildings

Figure 3. Example of cavity barrier in ceiling void (fire protection board).

Figure 4. Example of cavity barrier in ceiling void (mineral wool).

Cavity barrier Compartment

floor