They may use special weld pins with integral-cupped head washers. Unfaced boards can then be completed with bolstered insulating cement, canvas, or weatherproof mastic. Confronted boards might be put in in exactly the same way, and also the joints involving boards sealed with strain-delicate tape or glass material and mastic. https://freeecogrants.co.uk/simple-steps-to-apply-for-an-eco-grant/