Natural slate has long been considered to be one of the most environmentally friendly building materials in the world. Slates have the lowest carbon footprint and least environmental impact of any building material because there is very little to the extraction and manufacturing processes. Other materials, for example, ceramic products, need high temperature firing in furnaces, meaning they consume far more energy to produce than slate does.
Once installed on the roof, natural slate remains totally inert, with no chemical emissions; it retains its strength and colour, and easily withstands adverse conditions such as heat, cold, wind, and rain. Good quality slates are unrivalled in their service lifespan; with proper care and maintenance, a slate roof can last in excess of 100 years. Probably the other roof materials, such as timbers and metal fixings, will deteriorate long before the slates do, which is why there is such a ready market for second-hand slates.
Of course, the way in which slates are traditionally installed on a roof is quite labour-intensive – this is true of all double lapped roofing products. There are limitations to the way in which natural slates can be installed, with known relationships between slate length and width, headlap, side lap and roof pitch to ensure water does not find its way through the slating. BS 5534: the British Standard Code of practice for slating and tiling, provides guidance on minimum headlaps, side laps, rafter length, and roof pitch to ensure that the slates perform correctly in resisting rainwater ingress and wind loads.
But, what if natural slates could be installed in a way that reduces labour costs and, at the same time, allows their use on roof designs that previously was not possible? The Permavent Easy Slate system tears up the rule book when it comes to roof pitch and slate laps. Easy Slate has a unique system of side interlocks, channels and water bars in the form of a strip that fits under each joint, preventing water from creeping sideways, enabling slates to be used on roof pitches as low as 12 degrees. The slates are still installed in a double lapped pattern, so there is no discernible difference in appearance on the roof. This all means, particularly for low pitched roofs below 30 degrees, that slates headlaps can be reduced and so less slates are required, further reducing the environmental impact of the finished roof.
We have some extremely efficient underlays, such as the Permavent DRY vapour-permeable and condensation-control membrane. Permavent DRY incorporates a super absorbent fleece that is designed to capture a high level of condensation which may form within the roof space at peak periods during the day. It then slowly releases this as water vapour out into the batten cavity.
Once the water vapour has passed into the batten cavity, it must be removed to prevent excessive condensation forming on the slate battens and undersides of the slates. The Easy Slate system increases the gap slightly between each slate, not only eliminating capillary water creep, but also encouraging air flow between the outside atmosphere and the batten cavity. This further improves the efficiency of the Permavent DRY membrane in removing unwanted condensation from the roof structure.
To complement the Easy Slate system, Permavent also offers unique verge, valley, and side abutment systems to eliminate the need for mortar bedding.
Easy Verge is a continuous dry verge system for slates and is a great alternative to mortar bedding at the verge. The system has unique rubber super seals to prevent water ingress. It is quick and easy to install and provides a neat and unobtrusive finish to the verge. The system keeps water away from the slate batten ends and prevents water from running over the verge edge.
Easy soakers are suitable for all natural and artificial double lapped slates and incorporate our unique flexible super seals on high grade high impact plastic, which self-seals over the nail fixings. The system is available as individual 350mm long units (Soaker Singles) or as a continuous unit 3 metres long (Easy Soaker). The system is quick to install, and at up to 80% cheaper than traditional lead soakers is very cost effective.
Easy Valley is flexible and versatile and incorporates a central upstand which ensures water cannot run from one roof face and flood the opposite side, with highly efficient water channels to drain the water safely to the gutters.
In summary, the Permavent Easy Roof System provides an ideal, discreet low-impact solution for all slate roofs as low as 12 degrees on domestic, commercial and heritage properties. The system has been rigorously tested at the BRE and is approved by LABC and NHBC, and comes with a 40-year guarantee.