Slate Roofing in Cumbernauld

Cumbernauld stands on high ground with open country to the north and west, and wind is what every roof here is tested by. On a slate roof the risk is uplift: gusts get under the tail of a slate that is sitting proud, has a short head lap or has lost its nail, and once one goes the ones above it are exposed. Traditional Scottish slating answers that with heavy slates at the eaves, tight diminishing courses and a full sarking deck underneath, and the village roofs that have stood for two centuries prove it works.

What undoes it is careless repair. Slates hooked back with a bent nail, an oversized slate forced into a small course, or a mortar bedding that traps water all give the wind a grip. When we refix or re-lay slates on an exposed roof we keep the lap right, use copper or stainless nails and proper lead tingles, and make sure nothing sits proud of its neighbours. It is not complicated; it just has to be done every time.

Look up in the loft of a village cottage and you will see boards rather than slates. That deck of sarking is the Scottish way: slates were nailed once, through the head, straight into the boards, where an English roof hangs its slates on battens with two nails each. The boards brace the roof against exactly the wind Cumbernauld gets, and they are the reason many of these small roofs are still square after 200 years.

The slates were sorted by size on the ground and laid in diminishing courses, big at the bottom, smaller towards the ridge. Most of the slate on Cumbernauld’s older roofs is Scottish, from Ballachulish, the Slate Islands or the Highland Line quarries, and none of those has produced slate since the last Ballachulish quarry shut in 1955. Every matching slate we fit is therefore a reclaimed one, and part of the skill is grading it to your courses.

Nail sickness is the ageing of the single iron nail holding each slate. Once it rusts through, the slate slides. The tell-tale is slates slipping in different places on the same roof and a growing collection of lead tingles from past repairs. When that is widespread the slate needs lifting and re-fixing, and it is nearly always still good enough to go back on.

Inside the conservation area, North Lanarkshire Council’s appraisal and management plan is aimed at keeping exactly the stone-and-slate character you can see on Main Street. In practical terms: repairing or re-slating like for like in natural slate needs no permission; swapping slate for concrete tile, fibre-cement slate or anything else that changes the look of the roof is likely to need planning permission, and on a listed building will need listed building consent. Rooflights, new dormers and removing a chimney can also need consent. A building warrant is not normally required to re-cover a roof in the same material, but it can be if you change to a heavier one or alter the structure. We check this with the council before we quote and tell you plainly which rules apply to your house. Outside the conservation area, in Condorrat or on a farmhouse, you have more freedom, but on a stone building slate still looks and performs best and is what a future buyer will expect to see.

Small roofs make the decision cleaner. On a cottage, a repair is a few hundred pounds and a full re-slate is often in the £6,000 to £9,000 range rather than the five-figure sums a villa attracts, so patching year after year stops making sense sooner. We look at four things: how many slates have moved, whether the slate is still hard or has started to flake, the condition of the sarking from inside, and the lead and ridge. Fewer than one slate in ten moved and dry boards means repair. Tingles every few courses, rust marks under the slates and a soft board or two means strip, repair the sarking, membrane, and re-lay with copper nails, re-using your slates and topping up with matching reclaimed stock. Good Scotch slate lasts well over 100 years, so a re-slate done now is the last one the house will need in your lifetime. The ranges in our guide to new roof costs in Scotland apply here too, at the smaller end.

Village cottages usually have a stack at each gable and, on the longer buildings, a valley or two where a later wing meets the original. Stepped flashings, back gutters and valley linings in lead are where these roofs actually leak, and on a roof that has been repaired piecemeal we often find cement fillets or sealant where lead should be. We put lead back, dressed by hand, and re-point or re-flaunch the stacks while the scaffold is up. Details are on our Cumbernauld leadwork page; for the wider picture on Scottish slate see the Falkirk slate roofing page.