Beneath a new membrane: VlamShield SHEET

VlamShield SHEET sits between insulation and new waterproofing. The 10 mm cement-bound glass-fibre board provides a mineral protective and load-spreading layer, with a mass of 10 kg/m².

The membrane above provides waterproofing. Fixing, support and staggered joints are coordinated with the complete assembly, including insulation and the supporting structure.

On the water-carrying level: WEER beneath PV

WEER addresses the mineral protective layer on the roof surface above the existing waterproofing and directly beneath a PV system. In design we consider PVC-P, granule-surfaced bitumen, PIB and TPO/FPO. The roof membrane remains the water-carrying level; the board takes on an additional mineral and mechanical task.

Whether the specific combination allows direct contact or needs a suitable separation or protection layer depends on membrane, board surface, movement and manufacturer requirements. Water must be able to drain beneath the board. Load distribution, wind restraint and access to seams are part of the installation concept. Weather resistance of the board material is a basis for this, not a finished connection drawing. [2]

As a layer applied on site: VLOEI

VLOEI denotes the cement-bound route for a mineral compound spread across the roof. It comes into consideration when a full-surface layer has to be adapted to the existing substrate. The first selection question is then not only "Which thickness?" but "How do substrate movement and adhesion interact?"

Substrate preparation, mixing water, application, layer control and curing become part of the construction sequence. Flexible synthetic membranes present different conditions from mineral granule-surfaced bitumen. A coating must not simply cover movement joints and outlets. The coating comparison explains the difference from roof waterproofing.

Edges and upstands remain separate details

WEER can additionally form part of a mineral protection detail at upstands, edges and penetrations. This additional application does not replace the design of the horizontal roof surface. At vertical elements, fixing, water management and loading change.

The transition from horizontal to vertical needs particularly careful drawing: where does the board end? Where does the membrane move? How does a connection remain inspectable? The same material in both zones does not mean the same fixing.

Survey the existing roof first, then choose the build-up

Old drawings show the intention; a properly resealed inspection opening and current photos show the existing condition. Insulation, moisture, fixing and reserves in the supporting structure decide whether an additional layer is economically worthwhile.

Where re-waterproofing is due anyway, a layer beneath the membrane can fit conveniently into the sequence. On intact waterproofing, a surface-laid solution is worth examining. Where the construction is damaged or saturated, the roof function must be restored first.

Membrane stays: compare WEER or VLOEI above it. New membrane: assess SHEET beneath it. Include added load and installation access in both cases.