They may use Particular weld pins with integral-cupped head washers. Unfaced boards can then be finished with reinforced insulating cement, canvas, or weatherproof mastic. Confronted boards is often set up in precisely the same way, along with the joints between boards sealed with pressure-delicate tape or glass fabric and mastic. https://freeecogrants.co.uk/why-should-you-apply-for-eco-funding-first-time-central-heating/