Slate roofing offers exceptional durability, as it is not prone to damage by extreme temperatures and is resistant to chemicals, alkalis and acids. Also, slate roofing always maintains its natural colour, even if it is exposed to a significant amount of UV light, and is impenetrable by water if installed correctly. Most of the time, Welsh roofing slates are removed from the roof after up to 100 years of service, as the roof timbers fail. The slate can then be reused for new roofing purposes. For instance, the Penrhyn slate from the roof of St Asaph’s Cathedral was removed 400 years after being installed, and was then reused.
Benefits of slate roofing include
- Lasting durability, offering over 100 years of service
- Resistant to most environmental conditions
- Quickly absorb colour and retain it without fading
- Visually appealing
- Can be installed in large, as well as small format slate
You can view samples of our slate roofing work online, and call GS Roofing to schedule a free slate roofing estimate.
GS Roofing provides its clients with the following types of slate roofing: Welsh Slates, Chinese Slates, Spanish Slates and Brazilian Slates.
Metamorphic rock, from which true slate shingles are produced is impervious and incredibly tough, however it can be split into thin layers that comprise individual slates. Unlike sandstone slates and limestone slates, the aforementioned material is mainly associated with Scotland, Cornwall, Wales, and Cumbria.
Slates can vary, and so can the instillation techniques. For the most part, true slate shingles are of irregular sizes, uneven and are installed in courses that lessen closer to the ridge. Welsh slates (starting from the 19th century) are an exception to this, as they are of regular sizes and have a smooth surface, which allows for instillation in uniform courses. These slates became incredibly popular as railroads entered the network of global transportation systems.
Slate Roof Installation
A ‘brick bond’ pattern is used during the instillation of slate roofing, which means that the joints between each slate are aligned with the centre of the slates above and below, leaving about 3mm of space between the sides.
This installation pattern allows for double covering, because the top part of each slate is covered the centre of the slate in the next row, as well as the lower part of the slate located above. The slope of the roof dictates the amount of overlap, and the steeper it is, the less overlap is required.
Shorter roof slates are used in the composition of the lowest row of roofing near the fascia board in order to provide the double overlap for the first row of full sized slates. As such, the lower edges of these short slates should coincide with the first row of the full ones. The top row of slates at the ridge of the roof is also composed of half slates for the same purpose. Ridge tile must cover the top edge of the first row down, which means that the slate should be installed at an appropriate level.
Aluminum nails are preferred to galvanized ones, because aluminum (unlike the galvanizing coating) does not corrode. For this same reason, stainless steel and copper nails are also acceptable.
There are two options for nailing the slates; at the top or the center. If the nail is located at the top, it is concealed by two slates, limiting exposure, however as the slates are secured at only one end, there is more risk of breakage and wind uplift occurring. Alternatively, placing the nail at the centre line of the slate does decrease the protection to the nail, however it also reduces the risk of slates being lifted by strong winds. The best option is generally to nail the slates at their centre with the use of non-corrosive nails, to compensate for added exposure.