There have been a huge number of attempts to manufacturer synthetic roof coverings that replicate slates and tiles, of which many have fallen by the wayside over the last decade for a number of technical and commercial reasons.
Typically they have been ‘recyclable’ but not made from high recycled content, so don’t tick the recycled content box, or others have suffered in the UK climate and curled upwards at their bottom edges leaving a rather unsightly appearance and reduced weather tightness from driven rain. Some designs haven’t addressed the spread of fire and are only suitable for garden sheds, whilst others haven’t managed to gain certification and warranties.
However there are now a few on the market with some very good credentials and suitable for the UK market. An excellent example is the Recycle 4 Slate, available from Ecomerchant, which is made from recycled polyethylene, with certification and a track record. The Recycle 4 Slate is manufactured from 95% recycled polyethylene and pigments, with binders for colour and stability.
Firstly we need to consider the product that Recycle 4 Slate is largely made from – polyethylene. The virgin polyethylene used to manufacturer drinks bottles and other food containers has been recycled for a number of years. The plastics recycling industry has become a global market, for example in Japan they recycle over 70% of their polyethylene and ship it to places like China for re-use. The UK recycles about a third of its plastics and the USA only about 20%, so there’s still along way to go with developing processes to recover plastics before it reaches landfill. The cost of separating and processing waste plastics globally had restricted growth, but now with the available technologies and commercial value in waste the markets are growing.
One of the remaining challenges is ‘down cycling’, which is each time a plastic is recycled it cannot be reused for the same quality product or use and is turned into a lesser product, so eventually we will have mountains of very low grade recycled plastic we cannot put to good use. So the major benefit in the Recycle 4 Slate is that not only is it a downcycled product but it can remain as a roof covering with a lifespan in excess of 50 years (unlike drinks bottles which have a life span of 300 to 500 years but only remain in circulation for one use, on average no more than a couple of months!).
The Recycle 4 Slate has other advantages over other synthetic roof slates, for example it has a BBA for use as a roof covering in the UK and has also been extensively tested for the USA market. The manufacturer is also able to warrant the product for 50 years which certainly helps re-assure clients that the product is durable.
Unlike many recycled slates the Recycle 4 Slate achieves a fire rating of AA when used in conjunction with a 6mm fire proof blanket & 11mm OSB, making it suitable for a wide range of applications including commercial buildings, terraced housing and individual dwellings.
The Recycle 4 Slate is normally fitted directly to the OSB which is fitted to counter battens, so the airgap is below the OSB. This is a rather unusual combination for UK construction, more akin to American roof shingles but makes the slates easier and quicker to lay and reduces the risk of vandalism as the Recycle 4 Slate are inherently flexible and can withstand high impact. Once the slates have been exposed to the sun for a summer they fuse together creating a homogenous roof covering and eliminating the risk of wind uplift and curling. The Recycle 4 Slate can also be warmed and moulded to form valley’s, hips and ridges which reduces the need for lead or other metals.
The more recent development of needing to penetrate roofs with solar PV and solar thermal panel fixings has lead to a number of claims for roof leaks. The Recycle 4 Slate can be used to reduce this risk as it can be cut to shape around fixings then heated to fuse the surrounding slates together which increases the strength and reduces the risk of ingress.
And they look like natural slate when installed!