Tuesday, 15 April 2014

Slating !

My roofer Andy is by profession a slater. He once said to me that he gets fed up of putting one slate on after another, and "thankfully" the restoration work at Balintore stops this from ever happening i.e. he works on all aspects of the restoration and indeed often has to rebuild the roof first before re-slating!  :-) However, given the sheer hard work in rebuilding the turret, I think Andy was pleased enough to get started with the re-slating. I can imagine this being the icing on the cake!

You can see the bottom row of slates being positioned. On the turrets at Balintore Castle, the first row of slates is square cut, subsequent rows are cut on the round - the so-called fish-scale slates that are very much the look of Scottish Baronial architecture.

Notice there is a little "kick" outwards in the shape at the bottom of the turret. This is called a bell curve, because it echos the shape of bell. This is labour intensive to achieve, but it is precisely the small details like this which give a building its class.

bottom square-cut row of slates on turret

It is fascinating that slating is one of the few remaining professions where hand tools still hold sway, and methods have stayed the same since time immemorial. In other fields such as carpentry, power tools have taken over. The photo below shows the three basic tools of slating.  There are two edging tools: the slater's knife and a "sage" to strike against, which put an edge on the slate; and a hammer to nail the slates in place.

the tools of slating

Below you can see how the knife and the sage are used to put a curve on the bottom of the slate. The speed Andy can put a curve on a slate is phenomenal: a few sharp chops at the right angles and of the right force are all that are required. If the slate is hit too hard or too softly, it could shatter! You chop the slate at the back surface to give a sharp edge here and a bezel on the front. If the bezel was at the back, it would draw the water underneath by capillary action, and cause the wood in the roof to rot.

how to cut a slate on the curve

It is important to sort the slates by size before laying. The roof at Balintore consists of "layered courses" i.e. the higher you go up the smaller the slate gets. This looks classy but is very labour intensive. I was intrigued by Andy's yellow rule - it didn't seem to be marked in either centimetres or inches. I have since found out it is marked in 3/4 inches, which is how you size slates! Historically there are regional variations: the slaters of Dundee used whole inches: the slaters of Fife used 1/2 inches. So Andy was apprenticed to use a sizing system, which would be reasonably compatible with either. 

the mystery markings on a slater's rule

If you have made it this far, you are much the better informed about slating. :-)


  1. It is rather interesting. I can't imagine much work for a slater in the area of the US (or the whole of it?) but I do suppose in your part of the world there would be some call for it. And just think, Andy's name will go down in history as the slater on the restoration of Balintore!

    1. There's a lot of historic housing stock in the UK, especially Victorian, which needs maintenance. Modern buildings can still use slate, rather than clay/concrete tile though nowadays you rarely see "fancy" slate work as at Balintore. The high rainfall in the UK dictates heavy duty roof solutions, rather than just shingles or whatever. So I'm sure Andy will be kept in employment. Very often roofers put their names into the lead work, so it's not just history but the historical record. :-)

  2. Oh, I"m sure he'll be kept in employment in the UK. I only wish we had half of the history here that you have there. In the warmer climates here (Particularly Florida) they use concrete barrel tiles. I guess the not-necessarily-better modern approach of 'slating'. They are supposed to help against the heat. Slates are so much more lovely to look at.

  3. In central Europe slate was already considered expensive as early as 1890 and in 1895 a replacement was invented - asbestos slate or fibre cement, best-known under the brand name Eternit. I guess the idea was it would last forever, hence the name. The company is still around and producing artificial slate, although without asbestos nowadays. It does last a long time - my parents have a roof that had the original clay tiles replaced with asbestos in 1971 and except for two broken tiles it's still perfectly fine. Those two were replaced with asbestos-free ones several years ago.