Roof systems

What can a metal roof do for you?

Built Up roof and cladding systems have been used for around fifty years in the UK and involve profiled steel or aluminium thin-gauge metal sheets. These profile sheets are often referred to by their shape: Trapezoidal profiles are those whose shape is based on a basic trapezoid or trapezium. Sinusoidal profile are based on the shape of the sine wave.  Standing seam - refers to the 'seamed overlap' on the sheet upsatnd and the secret fix refers to the sheet concealed fixing mechanism. These metal sheets can be taken to form a liner sheet and an external sheet, which are separated by a spacer system to create a cavity for insulation. Modern built up systems use more complex spacer bar systems designed specifically to reduce cold bridging and enhanced structural performance to accommodate the depth of construction typical of modern buildings.

Roof pitch more than 5 degrees

Trapezoidal roof systems - These systems are typically made up of a lightweight profile liner, such 19/1000 0.4mm gauge is often used. The 19 refers to the overall depth created by the profile, in millimetres; the 1000 to the effective cover width - i.e. one metre. 0.4mm is the material gauge. The underside colour is usually bright white. The spacer system is chosen to give the appropriate depth of insulation for the required U value. This insulation is usually of a mineral fibre quilt-type.The outer profile would typically be metre cover width, and often about 32mm deep, with the broad flat pan of the profile laid downwards, and the narrow corrugations standing up to direct water downslope. The quality of the steel substrate determines the durability and corrosion resistance properties of pre-coated steel. It is vitally important that a known supplier of the steel is used, with a guarantee offered direct from the steel manufacturer to the building owner, bypassing the contract chain.
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Roof pitch less than 5 degrees

Low Pitch roof systems are those designed to accommodate roof pitches down to approximately 1 degree, or large radii roof sections. These Low Pitch roof systems are themselves generically divided into two categories: Secret Fix profiles and Standing Seams. A Secret Fix system is a steel profile supplied in one long sheet length from ridge to eaves, or eaves to eaves on a curved roof. This eliminates the end lap and fixing penetration of the outer profile, which are both requirements when installing a trapezoidal profile. With a Secret Fix profile the side lap arrangement allows the fixing to be concealed, and the overlap of the sheet is a snap-on or clip-on attachment. This means that there is no penetration of the outer profile, and the weak points are eliminated. The other main category of low pitch roof systems is Standing Seam systems, usually supplied in Aluminium. Due to the higher coefficient of thermal expansion of aluminium (three times that of steel), this type of roof system has to allow for the expansion and contraction of the outer profile. Therefore the outer sheet is installed to a clip or halter on which the profile can slide. View pictures of this project

How good is the exterior coating?

Coated steel is supplied in accordance with a strict series of quality standards. The durability of the material is mainly dependant on the galvanised coating directly applied to the steel substrate. One such system is the galvalloy coating, which contains a blend of zinc and aluminium to provide enhanced protection to the steel. As a material, steel has a long history in light weight buildings, and contains a high percentage of recycled content. The combination of coatings offers good durability suitable for the UK's wet climate, and at the end of a building life the steel can be easily recycled, for information why not book a CPD Seminar? Modern coatings offer a 30 year guarantee without the need for maintenance, and with regular repainting after the 30 year period will often achieve an ultimate life in excess of 60 years.

The quality of the steel substrate determines the durability and corrosion resistance properties of pre-coated steel. It is vitally important that a known supplier of the steel is used, with a guarantee offered direct from the steel manufacturer to the building owner, bypassing the contract chain. View pictures of this project

Green Roof options

A new concept in Roofing - Green Roofs can be achieved using a standing seam system as a robust component of the system. Traditionally single ply sheets were used as a base for the green roof matt. Aluminium standing seam sheet offer the ability to enable the laying of larger roof areas with out the high risk of leaks caused during the installation of the soil and clay system over membrane. Extensive green roofs can be subdivided into a range of different systems dependent upon the composition and depth of the substrate and on the plant species used.
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