When choosing the roof of a house it is of paramount importance to ensure that the materials that you are using are of the highest quality and ‘fit for purpose’. Many people considering a slate roof will at the very least investigate the possibility of using reclaimed slate on their project. Cost, aesthetics, architectural specification, or desire to recycle are all genuine and acceptable reasons to want to use reclaimed slate.
As a slate ages on a roof its water absorption (WA) increases fig (i). Due to its hardness and durability this process is much slower in welsh slate than in any other slate. However when a Penrhyn Slate gets to about 150 years old its WA will be reaching about 1% and similarly a Ffestiniog slate of about 120 years old will be about the same. In our climatic conditions it is at about this level of WA when the slate starts to deteriorate. So a Penrhyn slate removed from an 1870 building may have less than 10 years useful life left. Even the age of a building may not give you the full story; is that the first time these slates were used, have they already been reclaimed once in their lives?
Having already been used in Ireland and the UK for many centuries, Bangor Blue slate has a proven track record. It has a guaranteed lifespan well in excess of 100 years, and its inherent strength and durability, make it a highly regarded and popular reclaimed slate. It can be taken down redressed and reused several times in its life. When choosing to use reclaimed it is advisable to take reasonable precautions to protect yourself and your property. After all, a roof is a lifetime investment and is the only thing protecting your home from the elements. The following factors should be considered when buying second-hand slate.
- Know the provenance of the slate that you are purchasing. Where has it come from?How old is it? Are the slates from the same batch? The last thing you want is a mismatched selection of slates or slates that have little life left in them.
- Check that there is no excessive damage to the nail holes and that they have not already been re-holed before (re-holing is a sure sign they have been salvaged before).
- Visually check each slate to make sure there is no deterioration to the front or back of the slate.
- Most importantly – the slate should ‘ring true’! When tapped, it should produce a clear ringing sound as opposed to a dull thud- those that do not ‘ring true’ should be discarded.
- Use an experienced slater when installing a natural slate roof. Slating is a skilled trade and should not be attempted by individuals with no previous slating experience.
- Purchase from a reputable company who will ensure you are buying genuine Bangor Blue slates.
Stay within these guidelines, and you should go some way to protecting yourself. If you have any concerns, get in touch with our team and we will be happy to advise you.
Susan Burrows works for Lagan Building Solutions Lisburn Northern Ireland – she has 15 years experience in both the concrete roof tile and slating sectors.
LBS are owners of the Penrhyn Bangor Blue quarry in Wales and are Ireland’s largest independent supplier of natural slate and clay roofing products. They have offices in Lisburn, Dublin and Belfast and have a helpful friendly team of technical reps covering all 32 counties.