Frequently Asked Questions (FAQ’s)

STEEL
STEEL DECKING (Bondek, Celdek etc)
CONCRETE SLAB UPGRADE
SEPARATING CONSTRUCTION
ROOF/CEILING CONSTRUCTION
HERITAGE FLOORS UPGRADE
AIR HANDLING DUCTWORK

STEEL

Do steel elements have to be cleaned? What if they’ve been exposed to the elements for a period of time?

Steel elements should be cleaned in accordance with any applicable standard before erection on site. Once erected the steel may be exposed to the elements for a period of time in which some rust is likely to form on its surface. Generally all steel surfaces to be sprayed should be clean and free from heavy rust, mill scale, oil and grease. Light rust will not affect the stickability of the fire spray.

When can our Contractors start erection of M&E services?

In order to maximise and retain the cost effectiveness of the spraying system, any services should be installed after spraying is completed. Where existing or new services must be installed before Spraying operations, these should allow for suitable clearance from the surrounding steel work, to enable the proper Vermitex 'AF' thickness to be applied without undue effort.

The steel has been primed with a rust preventative coating. Can the steel be sprayed?

Where paints with a melting point below 500°C are present Vermitex ‘AF’ may still be applied, however this will depend on the shape and size of the steel element. In some circumstances, reinforcement in accordance with AS 3784.1 (Section 8 - Methods of Mechanical Retention), may have to be employed. Please refer to LAF for further details.

Columns are located 75 mm away from the wall, what detail do I incorporate in my Design brief to bridge such a gap?

In certain conditions (static elements) Vermitex ‘AF’ is suitable for bridging small gaps up to 75 mm wide. For larger gaps subject to movement or vibration, suitable mechanical reinforcement must be employed to bridge such a gap.

The Building Code limits the size of steel members where fire spray may be applied without reinforcement. Does this apply to the Vermitex range of products as well?

Some building codes do apply ‘stickability’ restrictions to steel members that can be upgraded with standard Fire Spray materials without the aide of mechanical reinforcement. These restrictions relate to the size of the steel member and to materials that have not proven ‘Stickability’ under Fire Test conditions. LAF’s products such as Vermitex have amply demonstrated ‘Stickability’ when subjected to rigorous fire testing, on horizontal steel Plate 700 mm wide. Please refer to LAF for further details.

I have a 2 Hr Firewall terminating below the bottom flange of a steel beam, with 2 Hr firespray material applied to the beam and turned down the wall 150 mm. Is there anything else I should worry about?

When structural steel elements form part of are part of a Separating Element of Construction (partition, ceiling, etc) care must be taken to ensure that the Insulation Criteria requirement (mandatory in certain Standards) for Separating Elements of Construction is not impeded. In some cases the thickness of the fire spray may have to be increased to prevent an excessive rise in temperature on the ‘cold face’ of the separating element of construction.

Example:

A two (2) hr FRL is required on a partition which abuts the bottom flange of a steel beam. A fire has developed on one side and has been active for 2 hours. The temperature of the structural steel element is now 490° C, well within its critical temperature of 540° C. The corresponding temperature on the ‘cold face’ of the Beam however, (on the surface of the Fire spray furthest away from the fire side) is 385° C. In accordance with AS 1530.4 this temperature would have prescribed failure of the Separating Element of Construction as the Standard allows, at any one point of the Partition, a maximum temperature of 180° C.

As a result of the above any stored combustible materials or cables located in the vicinity of the steel beam could have ignited and thus contributed to the spread of the Fire.

STEEL DECKING (Bondek, Celdek etc)

We have an existing Bondek slab, what thickness of Vermitex do I require to achieve a 2 Hr FRL?

As with all Elements, in particular their behavior in Fire, it is imperative that the overall concrete cover thickness above the Decking be the same as the concrete thickness of the tested prototype. Special precautions must be taken to ensure that such a deficiency, should it exist, is catered for. Please refer to LAF for further details.

Slab thickness is OK, and equal to the thickness of the Tested prototype. Is there anything else I need to check?

With the older types of Decking systems e.g. Celdek, Bondek, care is to be taken to ascertain if the floor system has an in-built ducted system (Header Ducts). This is of principal importance as when reinstating a Spray applied FRL, these ‘Header Ducts’, more often than not, will require special attention.

How soon should the spraying of the cellular decking take place?

It is suggested that with the much older styles of Decking all heavy construction work (core drilling, jack-hammering, installation of ceiling suspension systems, etc) likely to generate severe vibrations, should be carried out before the spraying of the Decking occurs.

The decking is new and rust free, surely we don’t need to worry about anything else?

The surface of the Metal Decking (new or old) should be clean and unpainted. New decking may be contaminated with rolling compounds such as protective mill oils, grease, etc, and these oils could impede the proper adhesion of the Vermitex 'AF' to the substrate. Please refer to LAF for further details.

CONCRETE SLAB UPGRADE

What do we need to look out for in a Concrete Slab upgrade?

When considering the FRL upgrade of Concrete elements thorough investigation is required and some of the salient points are:

- Checking compliance of the overall Concrete thickness of the Slab member.

- Checking compliance of Concrete cover to the Top Steel reinforcing members.

- Checking compliance of Concrete cover to the Bottom Steel reinforcing members.

- Checking compliance of Concrete cover to the Beam/Column Tendon members.

Surely the spray will adhere to a concrete slab without any particular precautions?

The bonding surface offered by the concrete should not be overlooked. The surface should be unpainted without contamination from compounds such as formwork releasing agents, oils, grease, etc which may impede the proper adhesion of the Vermitex 'AF'.

We’ve specified the correct thickness of Vermitex to upgrade the slab, have we overlooked anything?

Even though a Concrete element may be fire upgraded with sprayable materials special attention should still be directed at ensuring that the appropriate Fire Resistance system is installed in Constructions joints, Control joints and Expansion joints. It must also be noted that lightweight Fire Protection materials have little or no compressive strength and cannot be relied upon as a replacement for concrete cover for the net structural requirements of the member(s) in question.

What precautions are needed in rectification of Fire affected buildings?

In fire affected buildings and in particular with fire damaged concrete it is advisable that specialist engineering advice be sought. Significant changes in concrete design strength (normally occurring at 300° C) result in color changes of the concrete aggregates, which are most frequently used. Texture and hardness changes are the superficial signs of temperature effects of concrete that has been significantly heated. Fire spraying over these areas is possible, in order to reinstate the original Fire Resistance Levels, however the net structural requirements of the member need to be addressed.

SEPARATING CONSTRUCTION

Can we suspend our M&E services from a fire rated ceiling or wall?

If services are required to be attached/suspended from Fire separating elements, then added structural supports may be necessary, to independently carry the additional load. This detail should be carefully planned as Authorities may consider parts of these structural supports (bracket, cleats, screws, bolts etc.) as breaches of the system and reject the integrity of the separating element.

Do we need to worry about ‘Slenderness Ratio’ with lightweight constructions?

The slenderness ratio for Vertical elements of Construction (walls) is an important factor which also affects lightweight partitions, and can have consequences for the stability of the wall during a Fire. Another factor, which can give rise to poor Fire performance (if not properly addressed) is the Restraining of the wall into the building framework.

So how do we overcome the ‘Slenderness Ratio’ problem with lightweight construction?

LAF system’s are an ideal solution for very high partitions, where structural members can be installed at the necessary centres to break-up the overall wall height. In many instances the system has been employed in providing separation for Fire Lift shafts where the available space to install such Fire barriers is often scarce.

ROOF / CEILING CONSTRUCTION

We need clearance for our M&E services to be installed between our FR ceiling and drop-in tile ceiling below. Can we fix the Fire rated Ceiling directly to the steel purlins supporting the roof instead of suspending it?

Fire Rated Systems must replicate the system adopted in the Standard Fire Resistance Test. It is not advisable to depart from the Manufacturers installation instructions and install a FR Ceiling System, directly to the purlins if the system has been tested in a Suspended mode only. LAF can offer Ceiling systems, which have been tested (SI-1589) in contact with the purlins and achieved an FRL of 240/240/240.

We need to support M&E services from the Fire rated ceiling. Do we need to include any particular design details?

Caution should be exercised if services are to be attached/suspended from any Fire Rated Ceiling system. Unless these extra loads (services) were included in the Tested prototype, added structural supports are required to independently carry the additional load. This detail should be carefully planned as Authorities may consider the projecting parts of these structural supports (bracket, cleats, clips etc.) as penetrations and reject the integrity of the Ceiling System. LAF’s systems cater for penetrating suspension clips for secondary ceilings and brackets used to suspend services below the Fire Rated Ceiling. These suspension clips/brackets must be attached to the Roof Purlins, or other structural members, and installed by the Fire Spraying Contractor, ensuring unrelated trades (Spraying, Secondary Ceiling and other Services) do not interfere with each other.

The Timber floor in question has 9 inch Joists, is this still OK?

The floor joists of the floor requiring upgrading must be equal or larger in size than the ones that were submitted to the Standard Fire Test for the relevant LAF systems. A practicing Structural Engineer may review the structural parameters of the floor with a view to reducing/redistributing the loads and ensure the system complies with the relevant code(s).

What happens when partitions adjoin the underside of the timber floor?

If Partitions are present and they abut the underside of the floor these must have equal FRL as the floor system. If not, the partitions should be cut back and finished 100 mm clear of the floor joists to allow the Fire Rated Ceiling system to carry uninterrupted throughout the floor, thus preventing Fire from exploiting the partition.

We have Pipes & other services penetrating through the floor, how do we address these Services penetrations?

Special attention is required for all types of penetrations through Timber Floor systems. In some cases these Services penetrations, should be totally isolated with proven non-combustible lightweight mortars to the immediate vicinity of the Fire collars. Please refer to LAF for further details.

The Timber floor we need to upgrade has an existing ceiling in place. Do we need to remove this?

With existing buildings being refurbished it is common to have an old ceiling in place. These are costly to remove, create numerous problems with their disposal and slow down the construction program. The LAF Vermitex system does not require existing ceilings to be removed, however due care must be taken to ensure that the Fire upgrading Ceiling installed over the existing ceiling is fixed through to the Floor joists and not to the existing Ceiling battens.

HERITAGE FLOORS UPGRADE

The Timber floor in question has 9 inch Joists, is this still OK? How do we address Services penetrations?

The floor joists of the floor requiring upgrading must be equal or larger in size than the ones that were submitted to the Standard Fire Test for the Foamed Vermitex 'AF' system. Special attention is required for all types of penetrations through Timber Floor systems. In some cases these Services penetrations, should be totally isolated with proven non-combustible mortars to the immediate vicinity of the Fire collars. Approval has been granted for the installation of Fire Collars within the ‘Foamed Vermitex’ system to cater for existing and new Services risers.

Should we take special precautions when retrofitting a ‘Foamed Vermitex’ system?

With Heritage Ceilings and especially when installing ‘Foamed Vermitex’ full floor examinations and careful planning are recommended. Please refer to LAF for further details.

How soon can we reinstate the Timber floor boards?

After the application of ‘Foamed Vermitex’ natural ventilation should be allowed (forced ventilation will expedite the process). In naturally ventilated conditions sufficient ‘drying time’ (3-6 weeks (1)) should always be allowed before the Floor boards are replaced. This is to prevent moisture being entrapped within the voids thus resulting in excessive moisture absorption by the Ceiling.

What preparation work is to be performed before the installation of the ‘Foamed Vermitex’ can proceed?

When installing ‘Foamed Vermitex’ we always recommend that a water-resistant sealant be applied (1) above the ceiling to prevent undue moisture absorption.

NOTE (1): If this is not carried out efflorescence or mould may appear to the underside of stable Ceilings and in the case of old and dilapidated ceilings this may have grave consequences, with the collapse of the Ceiling membrane a distinct possibility!

With such ceilings, we do recommend ‘stabilisation’ and in particular cases ‘full restoration’, before proceeding with the application of ‘Foamed Vermitex’ (please refer to Heritage Council of NSW or L & A Fazzini MFG P/L for information).

AIR HANDLING DUCTWORK

What are the maximum duct dimensions that we can safely Fire upgrade with Vermiduct?

The ductwork requiring upgrading must have dimensions not exceeding those Tested by LAF and approved by the CSIRO.

When do we need to Fire rated the hanging rods?

Stair pressurisation systems require full integrity of the system and therefore the hanging rod must have the same FRL as the ductwork. With Fire Engineered systems, and in certain particular circumstances (ie rod loads are below 50% of the maximum allowable load) Fire rating of the rods may be omitted. Refer to LAF for further details.

Smoke Exhaust systems are designed to extract hot gases from compartments affected by Fire. As the Fire is restricted to travelling inside the duct, some wrongly deduce that the suspension rods do not require FRL upgrading. The Fire may be restricted inside the duct but AS 1668.1 requires that the ‘System’ work under any circumstance. If the duct travels through a different compartment (which may be engulfed by Fire) the Designer must ensure that the duct will remain in place for the required period of time and the suspension rods must therefore be upgraded.

What metal gauge do we need to specify when employing Vermiduct as a Fire upgrading system?

For Kitchen Exhaust ductwork, AS 1668.1 requires the sheet metal to be of 1.2 mm gauge. With ‘Vermiduct’ 1.0 mm sheet metal is all that is required for ductwork up to 4.8 m wide x 3 m deep. In some special cases ducting not exceeding 1200 mm x 1200 mm may be constructed from .8 mm sheet metal. Please note however that in some cases (ie high pressure ducts etc) greater metal thickness may be warranted! Refer to LAF for further details.

The Fan units is located within the Plantroom compartment. Do we still need to Fire isolate the Fan?

Fan enclosures should be addressed with meticulous detailing. AS 1668 and other recognised Standards require the ‘full system’, not just the sheet metal ductwork, to be Fire Isolated. This means that the fan, as well as the motor should be Fire Isolated. LAF have systems which have been Tested and approved by the CSIRO to provide large (2.4 m x 5 m x 3.6 m high) enclosures with up to 240/240/240 FRL.

We need to commission the plant on completion and don’t want to permanently enclose our services (actuators, drives, smoke detectors, etc) and preclude them from full view with Access Panels etc. How can we retain full view of these items and still achieve the intent of the relevant Fire code?

Services (Actuators, motor drives, smoke detectors, etc) to be attached to Fire Rated Ductwork can remain in full view and at the same time be Fire Isolated. LAF’s tested systems include for the provisions of inspection enclosures fitted with proprietary intumescing grills to achieve a 2 Hr FRL. The Grills allow the relevant item (smoke detector etc) to remain in view through the grill at all times.

Email:sales@lafgroup.com