Inverted Warm Roof Construction

No vapour control layer is required.

Inverted warm roof construction.

An inverted roof is quite simply where the waterproofing layer is installed over the structural deck rather than over the insulation. Rigid extruded polystyrene insulation has minimal water absorption due to its closed cell structure. Simply defined as a type of roof construction where the waterproofing layer lies beneath the insulation instead of above it as in other forms of roofing inverted roofs ensure that the complete roof construction including roof covering is kept at warm temperatures during winter months and at moderate temperates during the summer months. In an inverted roof construction the principal thermal insulation layer is located not only above the roof structure but also above the waterproofing resulting in the waterproofing structural deck and support structure being at a temperature close to that of the interior of the building.

Warm inverted roof inverted roofs are a type of warm flat roof where the insulation is above the waterproofing layer. This makes it the only material suitable and approved for inverted roof applications. This means that the insulation should be highly resistant to water absorption for example an extruded polystyrene based product which will not be affected by water or repeated freeze thaw cycles. Inverted roofs are designed with the waterproofing layer usually a liquid applied membrane beneath the insulation.

Insulation boards are loose laid on top of the membrane and then weighted down with paving slabs or gravel ballast.