They may use Unique weld pins with integral-cupped head washers. Unfaced boards can then be completed with bolstered insulating cement, canvas, or weatherproof mastic. Faced boards could be put in in exactly the same way, plus the joints between boards sealed with strain-delicate tape or glass material and mastic. Loft https://freeecogrants.co.uk/tips-to-design-the-insulation-for-your-home-with-free-eco-grant/