Natural slate producer CUPA PIZARRAS has launched an online Fixing Specification Tool aimed at architects, specifiers and roofing contractors, generating project-specific slate fixing recommendations rather than leaving them to be worked out by hand from tables.
What it does
The tool takes the inputs that actually determine a slate fixing spec — site location, exposure, roof pitch and the slate being used — and returns tailored fixing requirements that can be dropped into project documentation. It is built around BS 5534, the British Standard code of practice for slating and tiling, covering exposure zones, headlaps and fixing requirements.
CUPA PIZARRAS says the tool is free and accessible at any stage of the design and specification process.
Why this matters on a roof
BS 5534 fixing calculation is the sort of thing that is well-defined on paper and frequently fudged in practice. The variables interact: wind uplift depends on site exposure zone and building height, headlap depends on pitch and exposure, and the fixing specification (nail type and gauge, whether tail rivets or clips are needed, whether every slate needs mechanical fixing) falls out of that combination rather than from a single lookup.
Getting it wrong is not an academic problem. Under-specified fixings on an exposed site show up as slipped or lifted slates in the first serious winter, and the liability for that lands on whoever specified rather than whoever laid. The 2014 revision of BS 5534 significantly tightened mechanical fixing requirements — most notably removing reliance on mortar alone for ridge and hip fixing — and pushed the whole trade toward calculated rather than customary fixing.
For a roofing contractor, the practical value is having a printable, manufacturer-backed spec to put in front of a client or a building control officer, rather than an assertion that "this is how we always do it round here."
Who it is for
Specifiers and architects are the named audience, but the more useful audience is arguably the roofing contractor pricing a re-roof on an exposed coastal or upland site, where the difference between a standard fixing spec and a fully mechanically fixed spec is a material line in the quote.
Watch for: whether the output is accepted as evidence by NHBC and building control inspectors in practice, and whether other slate and tile manufacturers follow with equivalent tools — Marley and Redland have long offered fixing calculators, so the direction of travel is toward every manufacturer providing one.
---