What is a vinyl cavity tray (vinylslabbe)?

A vinyl cavity tray is a plastic strip used as a damp-proof barrier in a cavity wall, replacing a lead cavity tray. In Dutch it is called a vinylslabbe, also known as a kozijnslabbe (frame tray). The cavity tray carries water that gets into the cavity to the outside, so that it cannot reach the inner leaf or the window or door frame.

Where is a cavity tray located?

In a cavity wall, rainwater can run through the outer leaf into the cavity. Above a window or door opening, that water is interrupted by the frame and the lintel. That is where a cavity tray is placed:

• Above the frame, over the lintel: the cavity tray slopes from the inner leaf to the outside and ends above the frame, just in the outer facade. Water in the cavity thus flows over the cavity tray to the outside.
• Between the frame and the inner leaf: as a seal that prevents moisture from penetrating inwards via the junction.

Versions

• On a roll: flexible and easy to cut to size. Disadvantage: if incorrectly fixed, the cavity tray can eventually start to ripple, which becomes visible on the facade.
• In fixed lengths: stiffer and neater, with preformed corners and end pieces.

Plastic cavity trays are available in various materials (including PVC and EPDM), with or without a welded-on insert strip that drops into the frame rebate.

Tips for correct installation

• Upturned ends (stop ends): turn up the ends of the cavity tray on both sides, so that the water does not run back into the cavity along the side. This is the most common mistake.
• Let the cavity tray drain to the outside: the outer edge must project just through the outer leaf or finish within it, with enough open perpends above it to let the water drain away.
• Overlap at joints: connect separate pieces with sufficient overlap and the adhesive or sealant prescribed by the manufacturer.
• Do not damage it during bricklaying: mortar on the cavity tray can form a dam; keep the cavity clean.
• Why plastic? Lead is heavy and is increasingly avoided for environmental reasons. A plastic cavity tray is lighter and cheaper, but check the warranty and the UV resistance of the visible part.

Related terms

• Lead substitute
• Lead
• Lintel
• Cavity
• Window or door frame
• Damp-proof barrier

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