Crinkly tin

The roof of this small building made of old shipping containers is clad with a sinusoidal profile steel sheet.

[edit] Introduction

‘Crinkly tin’ refers to sheets of profiled steel that are used for roofing and cladding buildings, mostly in industrial and other applications. The term is actually a misnomer as the sheeting is generally not made of tin. Today, the material mostly goes under the name of ‘profiled sheeting’, but may also be referred to as ‘wiggly’ or ‘wriggly’ tin, ‘corrugated iron’ or ‘galvanised sheets’.

Invented in 1829 as corrugated iron sheeting, the material was used in the late nineteenth century for building pre-fabricated buildings that were transported throughout the British Empire. It also became popular for agricultural sheds. Architects eventually found the material to be functional, durable, relatively economic, fast to install and with a potentially attractive ribbed texture and thus it came to be applied to numerous more permanent building types

Today, ‘crinkly tin’ is mainly made from galvanised or plastic-coated steel and is applied to elevations and roofs on a range of buildings that include warehouses, agricultural sheds, retail and industrial units, colleges and hospitals.

Specifiers can choose from a plethora of sheet types that are differentiated by their profile e.g trapezoidal or sinusoidal, pitch, thickness and colour. Sheets are also available that emulate roof tiles and pantiles at a fraction of the cost.

Generally used as a single skin, sheets for roofs are typically 0.7mm gauge and for walls 0.5mm gauge. Due to its thermal properties, condensation may occur either behind or below the sheeting. To avoid this, construction may incorporate insulation and vapour barriers.

[edit] Potential problems

It is common for steel sheeting to be coated with a very thin plastic layer to give protection against corrosion. However, this coating may be compromised on site when the material is cut to size, as the freshly cut edge will have no coating. The result is corrosion at the bare steel edge, and this will be exacerbated by rain and pollutants. Once corrosion starts, it can spread from the edges to other areas. Cut-edge corrosion is typically found at the eaves and sheet overlaps.

Corrosion may also occur when the metal expands in hot weather as the plastic coating may detach and allow water to penetrate. The ensuing corrosion may cause leaks and even perforation of the metal.

[edit] Related articles on Designing Buildings

• Decorative metal ceilings.
• Metal composite panels.
• Metal profile cladding.
• Metal roofing.
• Natural stone cladding.
• Plastic cladding.
• Rainscreen.
• Roof coverings.
• Roof tiles.
• Sandwich panel.
• Tin.
• Weatherboarding.