Chapter 1: Why are the slates on our old Highclere cottage slipping out of line?
What we find
Older slate roofs on country cottages were usually fixed with iron nails driven through the top of each slate into timber battens (the thin strips of wood the slates hang from). Iron rusts. After a century or more in damp downland air, the nail shank thins until it snaps and the slate drops a few centimetres, or slides out completely. Roofers call it nail sickness, and it tends to spread across a whole slope at much the same rate.
From the garden you may notice slates lying in the border, a gap showing a darker strip of underlay, or a slope that looks stripy where slipped slates sit lower than their neighbours. In the loft, you may see pinpoints of daylight and, on a wet day, drips onto stored boxes. The slates themselves are often perfectly sound.
What we fix
We start by checking whether the slates are worth keeping. A sound slate rings when tapped and does not flake when lifted. If most are good, we strip the failing area, fit new treated battens where the old ones have gone soft, and re-fix the slates with copper nails or stainless clips, which will not rust through the way iron did. Odd broken ones are replaced with reclaimed slate of the same thickness and colour so the repair does not stand out.
When the nails have failed across most of a slope, stripping and re-laying that slope is more honest than patching it every winter. Typical UK prices for slate re-roofing run from £120 to £180 per square metre for natural slate; your fixed quote follows the survey. Our slate roofing page explains the options.