Prepare the support and substrate

Before installation, check that the proposed substrate is level, capable of supporting the system and suitable for the loads. Soft insulation, loose granule surfacing or uneven support can change load distribution. The permitted arrangement follows from the actual board and roof system.

For DEK beneath new waterproofing, insulation and fixing are central considerations. For WEER above an existing membrane, contact compatibility and protection of the water-carrying layer also matter. Any contact layer is selected for the membrane and the intended loading.

Joints are part of the protective performance

Board joints can transmit heat, flames or water differently from the continuous surface. Joint width, support, any staggering and edge connections are therefore important properties of the assembly. An attractive product photo of an unbroken surface does not show these properties.

The ZAG report on BarrierSheet assemblies demonstrates why local effects at joints and damage beneath the layer must be considered separately. What is transferred to a project is a suitable construction, not just a material name. [1]

Design wind restraint by roof zone

Edge and corner zones may experience different wind loading from the interior area. Building height, surroundings and geometry influence the design. A board’s own weight alone is not a complete wind-restraint concept.

Mechanical fixing must not compromise waterproofing in an uncontrolled way. Ballasted solutions require the added mass to be included in the structural assessment. For bonded systems, the substrate, adhesive and workmanship form part of the relevant conditions. The responsible designer and installer determine these details.

Keep outlets and seams accessible

A board above the roof membrane does not automatically provide waterproofing. Water passing through joints must be able to drain along the water-carrying layer. Obstructions at outlets, low spots and unsuitable edge details must therefore be avoided at the design stage.

Define how important seams, drainage points and repair areas can be inspected. A removable or accessible arrangement can be economically valuable in service. For a continuous coating, repair and connection procedures need equivalent consideration.

Organise work areas and documentation

Store boards dry and according to manufacturer instructions, limit exposed work areas and arrange timely waterproofing: these steps belong in the programme for protected cover boards. Exterior boards also require suitable handling. Manufacturer documentation varies by application. [2] [3]

Photograph the substrate, fixing pattern, joints and connections before closing the assembly. Record the products used and the drawing revisions. Operation, maintenance and subsequent changes can then refer to the actual roof construction.

Include joints, wind zones, fixing and accessible outlets in the layout. Photograph these details before the membrane or PV modules conceal them.