They could also use special weld pins with integral-cupped head washers. Unfaced boards can then be completed with strengthened insulating cement, canvas, or weatherproof mastic. Confronted boards may be set up in the same way, along with the joints concerning boards sealed with stress-sensitive tape or glass material and mastic. https://freeecogrants.co.uk/how-to-apply-for-loft-insulation-in-the-uk/