Cembrit Cladding Products

Cemstone and Heavy Duty building board for external applications

Cembrit Cemstone and Heavy Duty Building Board (HD) are strong, durable and able to withstand extreme climatic and working conditions. With a density of 1700 kg/m³ they have been specially developed for exterior cladding and other exposed applications. They are offered in two sizes and five thicknesses.

The board is produced from a combination of cement, cellulose and mineral fillers. They are a hard, cement-grey surface, super smooth for easy pressure wash-down. Flexible to work with, they are extremely moisture-resistant and requires no painting.

Applications

Cemstone and Heavy Duty Building Board are strong and dense and offers high impact resistance. The board will not support mould growth, and resists termites and micro-organisms. They can be specified for any of the following applications:

industrial painting

backing for laminates

composite panels

exterior panels

exterior soffits

Authority

Class O to BS 476: Parts 6 and 7: 1981

Class 1 surface spread of flame

Technical information

Board sizes: 2440 x 1218 mm; 3050 x 1218 mm
Thicknesses: 4, 6, 8, 10, and 12 mm
Density: 1700 kg/m³

Weight

4 mm thickness 7.1 kg/m2
6 mm thickness 10.7 kg/m2
8 mm thickness 14.3 kg/m2
10 mm thickness 17.9 kg/m2
12 mm thickness 21.4 kg/m2
Temperature range maximum 150°C

Note: exterior cladding applications

When Heavy Duty Building Board is used for exterior cladding that requires laminating, painting or finishing with aggregate, there must be a cavity behind the board to ensure adequate ventilation. An air gap of at least 22 mm is needed to remove the condensation created by internal heat build-up. The air gap must not be blocked at any point, and must be open to the air at both top and bottom.

Fixings and fastenings

The Cembrit 40 x 2.3 mm nail is ideal for timber studs, and the 35 x 4.2 mm countersunk cutting head screw for steel studs.

Fittings are easily attached to Heavy Duty Building Board. However, satisfactory results will depend on the weight of the object and the type of fastener used. Heavy Duty Building Board’s strength allows all kinds of attachments to be fastened. Heavy attachments should be centered on internal studwork. Alternatively, reinforce fastenings with a backing piece behind the board.

Contact the Cembrit Technical Department for advice and recommendations on specific applications.

Whilst Heavy Duty Building Board is able to withstand extreme climatic conditions, its high impact resistance also makes it ideal for internal applications.

Fixing details

Nail/screw fixing positions (approx. mm)

Note:

For exterior applications requiring screw-fixing, pre-drilled holes 2mm larger than the screw size are required. The gap between boards should be equivalent to or greater than the boards thickness.

Examples of external and internal joints and junctions: timber or metal frames

For details of trims, channels, fittings etc, please refer to the Cembrit ‘Fittings and Accessories’ brochure.

Decoration

Finishing

Cembrit boards can be used in their natural state or finished with minimum inconvenience. Surfaces must be dry before decoration. It is advisable to leave work for two weeks after completion of building to allow humidity to stabilise.

Painting

Heavy Duty Board is so smooth it does not require sanding. As the board is cement-based, alkali-resistant paints should be used. Alternatively, a cement sealer can be applied to the surface.

Suspended ceilings should be coated on both faces and edges so that the boards do not bend in a humid environment.

Laminating

Heavy Duty Boards can be veneered and laminated using an alkali-resistant adhesive. In certain applications a balancing laminate should be fixed to the reverse of the board.

Note:

Acids and some salt solutions can adversely affect the boards. If contact with any of these is likely, the boards should be sealed.

Storage

The boards should be raised off the ground for storage and protected against adverse weather conditions. Supports should be at maximum 500 mm centres.

Boards should be moved to their place of use as soon as possible. If damp, they should be placed on edge to ensure rapid drying and good ventilation. Wet boards should never be installed.

Technical support

For technical support and applications advice, you will always find your supplier anxious to help. If he has no instant answer to your query, you can easily access the technical knowledge of Cembrit ’s own technical support staff to answer queries of a more fundamental nature and to advise on the suitability of particular products in specific applications.

Health and safety

For a health and safety data leaflet concerning the Cembrit product range, please contact the Cembrit Technical Support Department at the address below.

Handling and working

Dust is minimised when the following tools are used: circular saw with dust cover and collector keyhole saw/jigsaw for cutting large holes universal saw for cutting small quantities hole saw for drilling holes for sockets hand-scriber with hard metal point

Face masks are recommended when there is no vacuum extractor or when large areas of boards are being cut.

Also in the range of Cembrit high performance building boards and cladding panels:

Cembonit

Cemtone

High pressure laminate

Lightweight

Special performance

Multi-purpose

Lightweight ceiling tile

3.2 mm CH board