CPD: Fibre Cement
The full title of this CPD is ‘Fibre Cement: versatile, sustainable building material’. Its objectives are to introduce fibre cement products, their defining characteristics, advantages, history and predicted future
It also deals with these aspects of fibre cement products in the context of five types of application: weatherboard, roof slates, cladding, profiled sheeting and finally building and tile backing boards. Essential architectural principles of durability, impact resistance, fire resistance, breathability and sustainability, are also covered, with reference to fibre cement.
Part 1: What is fibre cement?
Fibre cement is a precisely formulated product comprising cellulose, water and cement, simply rolled, pressed dried and coloured, with a multi-layered fibre structure that makes it strong and long-lasting.
manufactured to ISO 9001 and 14001 or OHS 18001 standards, it can help architects achieve high brEEAm and Code for Sustainable Homes ratings. The fact that marley Eternit fibre cement is manufactured in britain helps it to achieve these ratings. It is available in a wide range of product types, textures and colours.
Fibre cement products can be used in all parts of the building envelope, including roofs and walls, externally and internally. because it is chemically inert, fire resistant and moisture resistant it also has potential applications for kitchen, lighting and sanitaryware products.
Part 2: History
Fibre-reinforced cement-products were invented in the late 19th century by the Austrian Ludwig Hatschek. Originally, he mixed 90 per cent cement and 10 per cent asbestos fibres, then added water and ran this mixture through a cardboard machine. This material, which was first produced around 1900, was initially used for sidings in house construction.
Due to its low cost, fire-resistance, water tightness, light weight, and other useful properties its popularity rocketed in the post war building booms. The first corrugated fibre cement sheets were used in building construction in 1906 and some of these original sheets are still in service.
For the last 40 years there has been no asbestos content in newly manufactured fibre cement. The formulation has benefited from continuous improvements in its manufacture and the range of fibre cement applications has been significantly extended.
Part 3: Benefits of fibre cement
High-performing fibre cement boards, used both externally and internally, can be finished with plaster, tiles or render. Their main benefits are durability, impact and fire-resistance, breathability, sustainability, value and colour range.
Most fibre cement products are non- combustible and achieve a Class 0 surface spread of flames. Fibre cement is vapour- permeable and, in areas with high humidity and moisture, reduces condensation.
The BRE Green Guide gives UK- manufactured fibre cement slates an A+ rating and UK-manufactured profiled sheet cladding can achieve A or A+. Factory waste can be recycled by returning it to the cement works and hard waste, being non-hazardous, can be used as hardcore. Fibre cement products are strong and lightweight, helping specifiers to reduce material quantities, including those required for foundations, and the amount of energy used. Fibre cement’s life expectancy exceeds 50 years in normal atmospheres.
Part 4: Weatherboard
Fibre cement is a good material for weatherboarding because it resists decay and maintains its appearance in exposed situations. It is low-maintenance and easy to install and can be used in the same way as wood but is immune to attack by pests and insects and also achieves a Class A2 EN 1350-1 fire rating. These benefits apply to all fibre cement building products, including those listed in the following sections: roof slates, cladding, profiled sheeting plus building and tile backing boards.
Fibre cement weatherboard is designed to replace and improve upon traditional timber clapboard and is fixed in a similar way, usually horizontally.
Part 5: Roof slates
This range of products can be used for roofing and, in the case of wall applications, tile-hanging and is available in a wide variety of colours and textures that can closely resemble natural slate. Fibre cement roof slates are lightweight, easy to work with and Guide ratings. Slates are completely dry-economical and can achieve A+ BRE Green Guide ratings. Slates are completely dry-fixed and ranges of fibre cement finishing accessories are available. The usual module is usually 600 x 300mm, although other sizes are available.
The typical duo-pitch ridge construction, shown here, has a dry-fixed fibre cement ridge capping. Felt battens provide for ventilation, just as with most forms of small element roofing.
Part 6: Cladding
Fibre cement can be used to construct weatherproof rainscreens, overcladding and interiors, taking advantage of the variety of colours and textures available. This form of construction can achieve high thermal and acoustic performance standards and a wide range of module sizes and fixing systems is available. The material is durable and impact-resistant, making it particularly suitable for off-site fabrication. A+ BRE Green Guide ratings can be achieved.
Used for rainscreen cladding, fibre cement cladding is available in a range of sizes, commonly 2500 x 1250 or 3000 x 1250mm, although other standard and bespoke sizes are available. Thicknesses range from 8 to12mm. A comprehensive range of fixing systems includes timber battens and multi-floor spanning rail and bracket systems. Concealed and adhesive fixings are also common. Cladding panels can be cut on site using power tools, but off-site drilling and cutting to size by specialist distributors is more common.
Part 7: Profiled sheeting
Fibre cement profiled sheeting can be used for roof and wall applications and is available in a wide range of colours. It is suitable for many building types, including educational, residential and especially agricultural. Its good acoustics are an advantage in livestock buildings and one of its benefits here is the fact that it does not rust or rot.
As with all fibre cement products, profiled sheets are light, easy to work with and economical; they can be cut or drilled on-site with ordinary power tools without special precautions. Sheets are 1,220 to 3,050mm- long and are 7mm thick.
Part 8: Building and tile backing boards
These products are suitable for interior or exterior applications and benefit from fibre cement’s tough and durable qualities and good resistance to water and fire. Fibre cement products are particularly suitable for tile-backing, fascias and soffits and for the application of plaster, tiled or render finishes. They come in a range of sizes and thicknesses and can be fixed to timber or metal support systems at various centres, depending on whether the application is internal or external and on wind and impact loads and the type of decorative coating.