Cussoms, followers and short cocks: the slate names

No two slates on a stone roof are alike. Quarried limestone yields small pieces in abundance and big ones sparingly, as Cotswold District Council's 2000 technical guidance observes, so a roofer ends up with a pile in every size and a job that depends on putting the right size in the right place. Naming the sizes made that work quick. A slater could call for cussoms or followers without a tape in hand, and everyone on the roof knew where each belonged.

The names are also a record. When a roof is stripped, the sorting that follows is done in the old vocabulary, and the stone goes back up in the order it came down. Knowing the words lets you read a quote or a survey note for a stone roof without a translator. It also shows why a firm that speaks in these terms is working from the layout of your roof, not from a generic price list.

How the sorting works in practice

When we strip a slope, the stone comes down and is stacked by length, so each pile holds slates that belong in the same band of courses. Counting the stacks tells us how many of each size survive in good condition and where the gaps are. A repair that needs six more long slates for the eaves is a very different order from one that needs six short ones for the top, which is why the sizes appear in the quote. Nobody can price stone honestly from a count of slates alone.

At the foot of the slope sit the biggest slates. The council says they are usually around 600 mm long, a few reaching 750 mm, and that they are laid as a doubled course along the eaves. These are the cussoms. Doubling the lowest course matters because the bottom edge takes the full run of water from the slope above and delivers it to the gutter, so it needs the deepest cover. The second layer also gives the lowest edge extra thickness of stone where drips, ladders and falling debris do the most harm.

The course immediately above is the followers. The word does what it says: the slates that follow the cussoms up the roof, each course a little shorter than the last. Between them these two courses form the foot of the roof, the part you can see best from the lane or the garden, and they are usually the first thing a surveyor checks from the ground, because a cracked or slipped slate at the eaves is easy to spot and easy to date by its weathering.

At the opposite end are the short cocks. The guidance describes them as the smallest slates, kept for the very top of the slope, and only about 150 mm long. They sit beneath the ridge, where the water load is lightest, so they can be short without harm. From the followers to the short cocks the courses shrink in steady steps, which is the origin of the term diminishing courses.

That gradual taper is the visible signature of a traditional Cotswold roof. Our guide to diminishing courses shows how the batten spacing follows the slate lengths. To put it plainly, this page is the vocabulary and that guide is the method.

Why not just use one size?

Because the quarry never produced one size, and because a uniform covering would look out of place on an old building. The variety is part of what lets the roof settle into the landscape. Stand back from an old stone cottage and you can see the courses shrinking towards the ridge, with the eye pulled upwards by the change in scale. A flat, even covering would remove that effect, and so would a modern lookalike with every piece cut to the same size.

The same document uses a few more terms. The hand-split limestone called Forest Marble gives slates known as presents. Swept valleys, where the courses curve around the meeting of two slopes, are built from specially cut pieces, and the guidance lists a bottomer, lie-byes (also called side skews) and skews among them. Ridges were always a plain angled block of dressed stone.

You need not memorise any of this. If a quote uses one of these words, ask where it applies on your roof and how many pieces are needed. A description reading only stone slates, with no sizes or positions, is too vague to compare with another quote. Our answer on where new stone slates come from explains how sizes are supplied when new stone is needed.

The sizes in each course change how much new stone a repair needs, because a long slate for the eaves costs more per piece than a short one near the ridge. They also affect how a loss is described to an insurer. A claim that lists the damage by course and size gives the loss adjuster something concrete to check. Our answer on insuring and claiming for a stone roof covers the paperwork.

At a survey we photograph every slope and note course sizes and any slipped or broken slates by position, so the quote can say which course needs attention. The written quote follows the visit, and stone, pegs, battens, labour, scaffold and waste are each given a figure. Our workmanship is covered by a written guarantee of ten years. Start from our Cotswold stone roofing page to see how the work is arranged.