Cold roof upgrade
Cold roofs are the traditional or old method of building flat roofs in this case the insulation is placed between the joist, therefore leaves the roof decking and joist cold, causing thermal bridging. Cold roofs require a void between the top of the insulation and the roof deck. This void must be ventilated to prevent the build up of condensation which could lead to mould or damp. This roof design is generally not recommended as a design for new build flat roofs by architects and engineers.