GreenCoat® PLX Colour Coated Steel Fully Supported Traditional Standing Seam Roofing - Standing Seam Roof

Guidance for specification option:

The European Standard is EN 636-3 - for use in exterior conditions including liquid, water or water vapour in damp but ventilated locations.

Service Class 3 in Euro Code 5 covers plywood to be used in climate conditions leading to a higher moisture content than in service class 2.

The minimum board thickness must be 18 mm (or layers of thinner boards that combine to achieve the minimum 18 mm thickness for curved coverings).

The plywood face laminate must be free of knots and defects and should as a minimum be "Good one side". shuttering ply is not suitable.

Guidance for specification option:

Also known as sterling board, it is formed by layered flakes of wood in specific orientation. Its wooden strips are compressed and bonded together with wax and resin adhesive. It is a cost effective option.

Care must be exercised when used as a substrate under traditional metal roofing and should be protected from moisture during construction. It is advised that screw fixings are used to ensure good pull-out values.

Guidance for specification option:

Complies with 8S5268: Part 2 (strength class SC3), or EN 1611-1:1999 (sawn timber normally with a maximum moisture content of 22%).

There are some woods which are not compatible with roofing metals, due to high acid content.

UK recommended practice is a range of 18 mm to 25 mm thickness, in widths of 100 mm to 125 mm and laid with 3–5 mm gaps between the boards parallel to the eaves.

In some cases, because of the nature of the building's structure, a diagonal boarding layout is used.

It is particularly important to note that timber protectives, preservatives and adhesives used in plywood board construction can react with the roofing metal and if applicable, suitable separation layers must be used.

Guidance for specification option:

Insulation must be structurally self-supporting or supported when installed so that it will not sag and form unvented voids or cause loss of thermal efficiency.

An insulation used as a directly supporting substrate must have a minimum compression strength of 50kPa (0.5kg/cm2) with deformation limited to a maximum of 10%.

The insulation must also be dimensionally stable up to 100C. Warm roof fixings including stainless toothed plate and sliding clip, plastic peg and fixing screws are used in conjunction with an insulated deck.

Guidance for specification option:

The composite panel is constructed from factory produced interlocking steel or aluminium panels, encasing an insulation core (PIR or other). The panels are laid across the roof or wall supporting rafters or rails.

The interlocking joints must be sealed with gaskets or sealant and taped according to the manufacturer's recommendations, with sealed metal closures to hips ridges, verges, eaves and penetrations. The total area and abutments must be sealed airtight.

This type of construction gives a good vapour sealed substrate and can be quickly constructed.

Guidance for specification option:

Alternative non-combustible supporting substrates, such as metal profiled sheets and fire rated sheathing boards are now commonplace due to changes in building regulations.

These are a direct substitute for plywood or similar and should be evaluated based on their pull-out values. When a metal profiled sheet is used, fixings must be rivets or self-drilling screws.