How to fix natural slate roof tiles: a course with CUPA PIZARRAS
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. Although, after a 220 mile journey, a warm welcome was received at Rowlands Roofing. A mug of tea and despite the weather, I felt ready to tackle the task of learning more ‘hands on’ about the product I sell: natural roof slate.
Members of our CUPA Pizarras team were invited to partake in a practical fixing course of a natural slate roof tiles. For those who don’t know, 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. An aspect frequently not given the due care and attention it requires or overlooked completely. In modern times it's easy to see why the is the case. With the pressures inflicted upon the industry, but it pays dividends to sort and grade the slates into at least three standards; namely: thick / medium / thin. It makes the task of laying them without gaps and variations easier. This job completed, and with the rigs battened out and ready to go, we got 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. We set about marking batten centres and perp joint spacings in order to ensure correct fixing 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. This provides 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.
Slate cutting by hand
In order to create a feature pattern within the roof area we cut scalloped slates by hand using the traditional method (Slate axes). 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.
We slated a seperate roof area using hook fixings as opposed to nailed slates. This method is popular in some areas of the country. Indeed there are contractors that always employ this method as standard practice. 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.
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? Returning to the work area we found our roofs had been sabotaged. The slates broken! Our next lesson was ...
Repairs to the roof
Using a slate ripper and a lot of grunting! (I thought copper nails were classed as soft metal!) the top parts of the broken slates are removed. However, 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. The day provided a better understanding of the problems they face on site. No two natural slate roof tiles are the same! 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.
A short video on how to install natural slate can be viewed on here.
Please browse our range of CUPA PIZARRAS slate here. And contact us via webchat or at your local depot for any further assistance.