Vermitex^® '7' FS

Lightweight Screed
(Interior Exterior applications)

Product Description

Vermitex^® ‘7’ FS lightweight screed is a mixture of Vermiculite and Cement which can be applied over a variety of roofs and floors. Vermitex® ‘7’ FS lightweight screed does not spall nor crack under mechanical impact and is resistant to thermal shock. In order to enhance its mechanical properties fibreglass strands may be added to the Vermitex^® ‘7’ FS, or alternatively may be reinforced with light gauge galvanised mesh where mechanical vibration can affect it’s adherence to the substrate. The material does not contain asbestos.

When using Vermitex^® ‘7’ FS lightweight screed in exposed locations - a water repellent protective membrane should be used, and water shedding details are required on junctions and abutments.

Recommended Uses

Application can be carried out by hand for small areas but preferably by mechanical means for large areas. Being a premix material, only water need be added on site and placement should be complimented by the use of mechanical mixers.

The material may be employed in interior or exterior locations for a variety of roofs and floors, with the aid of mechanical reinforcement if required (1). This Data Sheet addresses application to both Interior and Exterior Vermitex^® ‘7’ FS Lightweight Screed applications.

Product Characteristics

Tested Properties

Note: Some of the tested properties of the material may change proportionally to the change in Density.

Application Instructions

Vermitex^® ‘7’ FS material is a mill-mixed compound that can be sprayed/pumped over substrates that require levelling or insulation protection at the corresponding thickness stipulated by the Manufacturer. The substrate should be free from: battens, services (ducts & pipes where possible), brackets or any other components which prevent the proper installation of the Lightweight Screed system over the substrate.

Vermitex^® ‘7’ FS, when applied in well ventilated areas to a thickness of 50 mm, will dry in 2-3 weeks. Note that Vermitex^® ‘7’ FS is prone to frost damage and temperatures surrounding the Vermitex^® ‘7’ FS Lightweight Screed should not be allowed to fall below 4°C for a week, after installation. The Vermitex^® ‘7’ FS may be applied without any thickness restrictions. If multiple coatings must be employed, the new coating should only be applied over one that has partially set. Where this is not possible the last coating surface should be left with a ‘deep & rough texture’ or purposefully scratched. When ‘Trowelling’ or ‘Ruling’ is unavoidable the applicator should take care not to ‘overwork’ or ‘polish’ the surface.

Roof structures must be designed to carry the additional loads and the Vermitex^® ‘7’ FS Lightweight Screed should have an uninterrupted cover throughout. To reduce thermal gains/losses, service components that abut, discontinue or prevent the correct Vermitex^® ‘7’ FS thickness being applied, should be eliminated.

Vermitex^® ‘7’ FS may be painted over however suitable sealers and paints are required. (2)

Painted surfaces

Where Vermitex^® ‘7’ FS Lightweight Screed is applied over painted surfaces without the use of mechanical retention, it is necessary to ensure that the paint or membrane is in sound condition and properly cured. The paint should be Alkali resistant, been applied in the appropriate thickness in accordance with the paint manufacturer’s instructions. Good adhesion of Vermitex^® ‘7‘ FS to painted surfaces can be achieved in most cases, however, this is not always possible due to chemical incompatibility or high gloss surfaces.

When applying Vermitex^® ‘7’ FS over painted surfaces, mechanical reinforcement may be required. When mesh is required and to ensure that the paint/membrane integrity is retained, the mesh fixing method (eg capacitor discharge pins, rivets, nails etc) should be reconsidered to ensure it doesn’t pierce the coating/primer treatment.

The use of a mesh retention system ensures that Vermitex^® ‘7’ FS lightweight roof screed will remain in position and retain its primary function even if debonding occurs. If bonding to the substrate is regarded as of primary importance, ensure that the surface is coated with an alkali resistant paint, and consideration is given to the application of a Bond coat.

Concrete surfaces

To increase the bond between Vermitex^® ‘7’ FS and the substrate the concrete may be mechanically roughened or scabbled. A slurry of Vermitex^® ‘7’ FS and PVA emulsion may be laid first, immediately followed by the Vermitex^® ‘7’ FS Lightweight Screed. Note that the concrete should be at least 14 days old and that the surface be free of any form release agents.

Important: At no time should Vermitex^® ‘7’ FS be used as a ‘wash coat’ or applied in a thickness less than 15mm. The concrete substrate should be moistened with water to prevent premature drying of Vermitex^® ‘7’ FS.

Termination

All termination of Vermitex^® ‘7’ FS against substrates must be sloped to shed water. Where Vermitex^® ‘7’ FS terminates on columns etc., the Vermitex^® ‘7’ FS column junction must be sealed. Cut a groove not less than 10 mm deep by 10 mm wide into the column/material interface and apply an approved sealant. Alternatively, use an appropriately shaped Galvanised metal cowl, and seal any gap between the cowl and the Vermitex^® ‘7’ FS with silicone sealant.

Bond Coat, Compatibility, Corrosion prevention & Vapour control

In certain applications,Vermitex^® ‘7’ FS may be applied directly onto the bare steel without the need for a steel primer (Refer to LAF for further detailed advice). If a concern exists about moisture causing corrosion, the substrate should be suitably primed with an approved rust preventative primer. Where primers are required alkali resistant primers are recommended, however the paint manufacturer should be consulted to ensure compatibility with the Vermitex^® ‘7’ FS LAF have a comprehensive list of compatible primers and will supply on request.

Chemicals that have an impact on cement will also have an impact on Vermitex^® ‘7’ FS. In these circumstances the material must be top coated with suitable sealers and paints for protection. Paints based on two pack epoxy resins, chlorinated rubber, solvent based vinyl or solvent based acrylic are normally satisfactory when applied according to the paint manufacturers instructions (Refer to LAF for more details).

Vermitex^® ‘7’ FS may react with Aluminium and Aluminium alloys and a suitable primer is recommended.

Moisture trapped in a roof, construction water, rain or condensation may be a potential source of such problems such as blistering and ceiling stains and may also reduce the overall insulating value of the screed. Consideration should be given to measures which allow free water or moisture vapour to escape. These include the drilling of slabs at low points, the installation of ventilators in the roofing membrane and the complete venting of the screed by means of ducts and ventilators.

Coverage

One 50 litre bag of Vermitex^® ‘7’ FS will cover approximately 1m² at a nominal thickness of 50 mm (without wastage considerations).

Vermitex^® Specification (Broad Form)

Prior to Vermitex^® ‘7’ FS application commencing, the substrate shall be inspected by the Main Contractor to ensure all areas to be covered are free from any substance which may impair adhesion of the material.

Mechanical reinforcement, shall have been installed in accordance with the Manufacturers instructions, relevant Codes and Standards, alternatively, if approved by the Client or Designer, a thick slurry of Vermitex^® ‘7’ FS and PVA emulsion may be laid first, immediately followed by the application of Vermitex^® ‘7’ FS lightweight screed.

All adjacent areas not requiring treatment shall be suitably protected against splashes.

Vermitex^® ‘7’ FS as manufactured by L & A Fazzini Manufacturing Pty Ltd shall be installed by an approved Specialist Contractor to the thickness of ..xx.. mm (insert required thickness). .

The Specialist Contractor shall provide all materials, accessories, spray equipment, tools, inspection services and labour to satisfactorily carry out the works in best trade practice. All workmanship and installation techniques shall comply with the Manufacturers ‘Application Instructions’, relevant Building Code Statutory requirements and applicable ASTM, BS or AS Standards.

Health Statement

Vermitex^® ‘7’ FS contains no asbestos and presents no known health hazard before, during or after its application. The normal precautions relevant to the handling of cement based products apply, for example; dust mask, eye protection or the covering of sensitive skin.

NOTES:
1. Refer to LAF for mesh requirement details and for other Vermitex^® ‘7’ FS applications.
2. Refer to LAF for further detailed information.

For more information or MSDS on Vermitex^® ‘7’ FS or any other products,

please see the technical data page, or contact: L & A Fazzini Manufacturing Pty Ltd

Email:sales@lafgroup.com