Shingle

Frequently asked questions

What is a square, and why is roofing sold in them?

A SQUARE is one hundred square feet of finished roof surface — not of material, which is the distinction that matters when ordering. Shingles are sold in bundles that make up a fraction of a square, typically three bundles to one, and the number is expressed in squares because it makes the arithmetic of a roof easy in a trade that works in feet. The two ways it goes wrong on a job are worth separating. First, a square is the COVERED area after laps, so a bundle covers less roof than the material in it measures; the bundle count already accounts for that but a hand calculation from material area does not. Second, the area is of the roof SLOPE rather than of the building footprint, so a plan area has to be divided by the cosine of the pitch before anything is ordered. Both errors under-order, and a roof short by half a square stops at the worst possible moment.

What is the difference between a shingle and a shake?

How the wood was separated, and it changes both the look and the performance. A SHINGLE is sawn, so both faces are flat and the taper is even; a SHAKE is split along the grain, so at least one face is riven and irregular and the thickness varies. Splitting follows the wood's natural fibres rather than cutting across them, which makes a shake more durable and more resistant to water travelling along a cut grain — and rougher, thicker and considerably more expensive. The practical consequence is in the underlay: a shake roof's irregular surface leaves gaps between courses, so interlayment strips are laid between them, where a sawn shingle roof sits tight enough not to need it. In British usage both words appear only in specialist work, which is why the distinction is usually met first in an American specification where it is assumed knowledge.

Why does a British roof use tiles where an American one uses shingles?

Climate, fire history and the cost of the local material, in that order of effect. British roofs are pitched steeply and see persistent driving rain rather than extreme heat, and clay and slate were quarried locally and last a century or more, so the covering that became standard is a heavy, rigid unit hung on battens. North American housing built out in timber at speed over a continent with no comparable slate industry, and an asphalt strip nailed directly to a sheathing deck was faster, lighter and did not need a structure designed to carry it. The consequence for anyone reading across markets is structural rather than cosmetic: a tiled roof weighs several times what a shingled one does, so a rafter and wall design sized for one will not simply accept the other, and re-covering a roof in the other market's material is a structural question before it is a roofing one.