Blue Bangor Slates – Welsh

Blue Bangor Roof Slates (Welsh)

Heather coloured natural roof slates – generically known as Blue Bangors – mostly came from a number of Welsh quarries such as Dinorwic, Penrhyn, Dorothea etc. Penrhyn Quarry is the only Welsh producer today.

Reclaimed BLUE BANGOR roof slates.

In Ireland a popular second-hand slate is the RECLAIMED Blue Bangor roof slate. Quarried in North Wales, it had easy access to shipping traffic from Holyhead to Dublin port.

We have supplied salvaged roof slates to numerous Restoration projects from 100 m2 on a cottage to 2,500 m2 on a public buildings over the past 30 years. These old slate roofs retain their traditional appearance – they look old – and they will be enjoyed by generations to come.

We participate in events run by the Irish Georgian Society, The Heritage Council and Dublin Civic Trust. Killoran Slate & Tile are committed to play our part in preserving Ireland’s built heritage for future generations.

Old Roof restored with Reclaimed Blue Bangor slates


In Ireland today slates quarried from the”Cambrian” Rock in North Wales are generally referred to  as  Blue Bangor slates. The slate quarries included Penrhyn,  Dinorwig, Cilgwyn, Cefn Du, Penybryn, Tal-y-Sarn,  Pen-Yr-Orsedd and Penrhyn. These old roof slates vary from dark heather colour to deep purple and Plum Reds.

Product Range

We have been salvaging old roofing slates and tiles for over 25 years. We have supplied Reclaimed Blue Bangor slates in every county. We have large stocks of Sized slates from 10″ x 6″ to 26″ x 14″, and Random slates from 12″ long to 40″ long. Randoms are mostly laid in Diminishing courses. The most important point to remember is tha the minimum HEADLAP is maintained at all times. We simplify the slating process by providing computerised COURSING SCHEDULES so the Slater can batten the complete roof in advance. We then supply the crates of slates, one length only per crate, to match the coursing schedule. Some suppliers supply randoms by the TON so the Slater has to lay out the roof on the ground before he can commence battening the roof.

Randoms laid in diminishing Courses

A classic natural slate roof was usually slated with random slates laid in diminishing courses. This best suited the quarry production, especially small quarries, as all production sold equally. In the old days quarries produced all sizes of rectangular slates.

The target was to produce the largest slate possible from a piece of slate block. Block was originally extracted by hand with crow bars, using the natural cracks in the quarry face. Splitting  (riving) was done in little make-shift huts. If the slate split at 25″ x 13″ then it was shortened to 24″ x 13″ wide. There was no point in wasting coverage by reducing to 12″ wide. Quarry production resulted in a whole range of sizes so it was sensible to slate the roof with a whole range of sizes.

When we produced new ” KILLALOE “slates at Killoran Slate Quarry in 1990’s, we dressed our slates to the optimum rectangular size. The width of a slate did not matter as long as we made it a standard length. We then crated the random roof slates into crates which contained about 20 square metres of roof cover. A roof of 100 square metres would take 5 crates so we delivered one crate of 20inch long, one 18 inch long, one 16 inch, one 14 inch and one 12 inch, making 100 square metres in total.

A traditional RANDOM slate roof may start with 32″ long slates at eaves and diminish to  22″ long slates at ridge. Likewise it could be 22″ long slates at eaves down to 12″ long slates at ridge. The choice of sizes very much depends on the roof size and its rafter length. Historically it was normally either 4, 5 or 6 increments of 2” each depending on the rafter length. This was the most effective way to cover a roof as you are using all sizes of slates produced by a quarry instead of a single size.

Today, with mechanised production, quarries set out to produce a limited range of sizes viz. 60×30 and 50×25. Large slate  blocks are extracted by large mechanical diggers after diamond wire sawing. The emphasis has shifted from large size slates to large quantities of smaller size slates.

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