We help to conserve traditional building forms and details by how we design and specify our own new buildings – not merely the renovation of old. The roof of the new shed on the croft, down by the shore, is being covered with the galvanized* corrugated steel sheets that are a traditional feature of older (mainly agricultural) buildings in the Highlands and (especially) the Islands of Scotland.
The sheets are specified by length, width, metal thickness and galvanizing*, and by profile. There are many many types of profile, but the traditional profile here is a sinusoidal curve, with a wave length (distance between ‘bumps’) of three inches. The overall height of the profile can vary, according to the manufacturer and the strength required. Here in the islands it’s essential that roofing sheets are robust enough to resist violent gusts of wind, which in winter frequently exceed 100mph. So, I specified ¾” height ; though, oddly enough, whilst the wave length is still commonly specified in inches, the height is usually given in millimetres : so, the height of our roofing sheets is 22mm. Hence the title of this post : 22/3 sinusoidal.
Corrugated sheets of this type were, from the late 19thC until after WW2, sent out across the British Empire in huge quantities as part of ‘kit houses’ for expeditions, pioneers, colonists, and farmers ; and the quality was so good that examples that are a century or more old and still in excellent condition can be found all across the world. There’ll be similar examples across the mid-west of the USA – made in the industrial east.
* Galvanizing : As a concession to modern technology, our roof sheets are, additionally, also be covered with a plastic coating.