There are 18 species of bats found in the UK all with different characteristics and habitation requirements, and there are many ecologists willing to offer varying opinions on what is or is not bat friendly. We would always recommend seeking advice from the Bat Conservation Trust, however the Trust now no longer endorses specific products for use without lengthy ecological studies.
The modern generation of lightweight high performance spun-bonded roofing underlays do however pose a risk to some bat species where it is possible that their claws will become entangled in the fibres and therefore should not be used in bat habitation spaces.
Lead has been in use in roofing for hundreds of years and due to its workability, it is versatile and can be very durable when used in the right quality and thickness, however the health hazards were not recognised until late in the 19th century.
Lead sheet and flashing has been awarded BRE Green Guide ratings of A and A+ when manufactured to British Standard BS EN12588, but this is based on its ease of long-life expectation, recyclability and due to a low melting point and high value, an equally high recycling rate. The high value also makes it a target for thieves.
In roofing applications, rainwater run-off is contaminated by the lead and therefore is unsuitable for many rainwater harvesting & recovery systems.
Patination oil can be used to delay the effect of oxidation that creates the white appearance and unsightly staining that affects roof tiles, slates and brickwork, but is also toxic and flammable.
It should be remembered that lead is toxic and banned in some countries. When using lead, operatives need protection from inhalation of lead dust and fumes, and absorption through the skin. Control of Lead at Work Regulations 2002 Approved Code of Practice and guidance (HSE L132) provides much more information and requires that where an alternative is available, it should be used.
The increasing extremes and unpredictability of UK weather in recent years has required changes in various Standards and requirements that reflect this. This has included the requirement for increased mechanical fixing of all products including roof tiles, and mechanical fixing where mortar might previously have been adequate.
Accordingly, a wide range of products to meet this requirement have been introduced into the market with an equally wide range of quality and performance. This new Standard is BS 8612:2018 ‘Dry fixed ridge, hip, and verge systems for slating and tiling. Specification’. First published in early 2018, it sets out to create minimum performance and durability standards for dry fix products used on ridges, hips and verges for slate and tile roofs.
Depending upon the material used, some products such as valley troughs and flashings manufactured from GRP carry a service life guarantee of thirty years, with an expectation that they will continue to perform well in excess of this period.
By their very nature, dry fix products can often be relatively quick and simple to replace at the end of their useable life.
In roofing, the term ‘dry fix’ generally refers to the installation of roof components without the use of mortar either as a fixing agent or filler, and more especially where mortar would have traditionally been used.
Product prices can vary for several reasons, but generally you get what you pay for. More expensive products are usually manufactured and tested/certified to higher quality standards and can be expected to be easier to use and perform better.