The Cwt-y-Bugail quarry in North Wales has been producing quality dark blue grey roofing slates from 1840.  Located East of Blaenau Ffestiniog in the Snowdonia National Park, it is the highest industrial site in the UK and although the site is now an open cast quarry, slates were originally mined in deep caverns and pillars.  In fact, during World War II, many of Britain’s most valuable paintings and national treasures were stored deep inside the slate caverns for safe keeping!

Referred to in Ireland as 'Portmaddog Slates' (after the port from which they were shipped)  the dark blue grey slates produced by this quarry have a “riven” texture and are famous, not only for their use as a roofing slate, but also as an architectural building material.  Although quite different in colour to the Bangor Blue slate, they share the quality and durability with which Welsh Slate is synonymous. 

Cwt-y-Bugail slates come in standard sizes of 500x250mm (20 x 10”), and in 3 thicknesses:

  • Capital Grade (5.5mm Nominal Thickness)
  • County Grade (7.5mm Nominal Thickness)
  • Celtic Grade (9.5mm Nominal Thickness)

Cwt-y-Bugail roofing slates conform to BS 12326-1:2014 (W1, S1, T1), hold BS Kitemark accreditation and are generally expected to outlive the life of a building (when fixed in accordance with BS 5534 / S.R. 82:2017).

Watch a short video of our Welsh slate fitted here

Product Detail

Kinsale Signal Tower Cwt Y Bugail Slate

Welsh Cwt-y-Bugail Slate Cladding

This is one of the most unusual and visually striking Irish building restorations that LBS have supplied. The Old Head of Kinsale Signal House on the Cork coast has, in 2015, been reborn as a Museum a…

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Colour and Finish Blue Grey
Available in Sizes 500 x 300mm (Other Sizes on request)
Available in Grades Celtic, County and Capital
Nominal Thickness Celtic 9.5mm, County 7.5mm, Capital 5.5mm
Minimum PItch 22.5 deg for standard 100mm h/lap *normal exposure only*(for pitches below 22.5 deg please consult LBS Technical Dept)
Maximum Headlap All LBS slates are holed for 100mm head-lap
Alternative Headlaps For availability and advice please contact LBS
Gauge 200mm for slate pre-holed for 100mm head-lap
Batten Size Please refer to BS 5534 or SR 82:2017
Nails Copper, Aluminium or Silicon Bronze
Slate Dimensions/ Grade 500x300mm Celtic Grade 500x300mm County Grade 500x300mm Capital Grade
Weight per sqm Laid (kg) 53.62 46.98 37.01
Slates per sqm at 100mm h/lap 16.6 16.6 16.6

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