Duncan Arnold from Cupa Pizarras writes




A wet and grey morning deep in the Hereford countryside wasn't the most inspiring time to attend a course on fixing natural slate roof tiles, even if selling the stuff is your day-to-day job. It has to be said, though, after a 220 mile journey, a warm welcome was received at Rowlands Roofing and after a mug of tea, despite the weather, I felt ready to tackle the task of learning more ‘hands on’ about the product I sell: natural roof slate.

I, along with other members of the CUPA Pizarras team, was invited to partake in a practical fixing course of a natural slate roof. For those who don’t know us, CUPA are the only true producer of Spanish roof slates that sell directly into distributors and natural slate suppliers in the UK. From our base in Northern Spain, we produce 180,000 tonnes/year of Spanish slate roof tiles; in layman’s terms, that’s 35 truckloads or 200 average size roofs per day.

The Grading process

We started the day with emphasis on the all-important grading process, which is often not given the due care and attention required or overlooked completely. In modern times, and with the pressures inflicted upon the industry, it is easy to see why this is the case but it pays dividends sorting and grading the slates into at least three standards; namely: thick / medium / thin in order to make the task of laying them without gaps and variations easier. This job completed, and with the rigs battened out and ready to go, we could start getting down to the nitty gritty job of laying the slate.

It’s not the same working on a ‘mock’ rig as being atop of a scaffold on a real roof, but for novices like me it was educational and we set about marking batten centres and perp joint spacings in order to ensure we were fixing correctly and our lines would remain straight throughout. These were small rigs, but it gave us an understanding of the importance of how this could affect the look of a large roof area if not correctly set out. 


Eaves slates were cut and fixed face down in order to provide the all-important support at the bottom of the roof and the line for gutter and fascia installation. The thicker selection of graded slates are used for the eaves course and at the lower level of the roof. We then continued to fix full slates above and worked our way through the selections of thick / medium and thin up to the ridge level. 

Traditional methods were employed to cut scalloped slates by using slate axes in order to create a feature pattern within the roof area. Slate cutters can also be used to shape slates or Cupa can provide shaped slates for projects to save time on site as cutting by hand with axes / cutters is quite labour intensive, and very tiring.

The rigs also incorporated a valley between two roof elevations so we learnt the importance of sidelaps and margins required to deflect water and wind driven rain away toward the valley or gutter and create a weathertight roof with the use of slate & halves with fixings positioned correctly to avoid the ingress of any water.

A separate roof area was slated using hook fixings as opposed to nailed slates. This method is popular in some areas of the country and there are contractors that always employ this method as standard practice as the slate is held securely at the tail avoiding any wind uplift. Especially useful in severe exposure locations or at heights above a standard two / three storey building.

Repairs to the roof

What more did I think we could fit into the day, my head felt full and I thought I had done well for the day, time for another tea? Upon our return to the work area we found our roofs had been sabotaged and slates had been broken! Our next lesson was in repairs to the roof. 

With the use of a slate ripping tool and a lot of grunting (I thought copper nails were classed as soft metal!) the top parts of the broken slates could be removed although without striping the roof from the top down the nails could not be exposed. We learnt the benefits of slate repair hooks and the method of fixing / installing them to provide an all but invisible repair which is safe and secure. 

I take my hat off to the true professionals that slate roofs daily and feel I have a better understanding of the problems faced on site. No two slates are the same and fixing them to provide a watertight as well as attractive roof is an art. There is no myth surrounding this trade, it comes down to experience, preparation and grading.

You can browse our range of CUPA PIZARRAS slate here. Please contact us via webchat or at your local depot for any further assistance.