Glazpart drain hole covers now come in a range of moulded colours to meet referenced RAL, BS or foil reference numbers. This means a significant reduction in the need for the paint spraying of drain hole covers to match profile colours.

Where a moulded colour is not available from stock, our paint spraying service can colour match and supply finished, sprayed drain hole covers within your quoted lead time.

Drainage

Most double glazing frames are designed with an inbuilt drainage system, comprising of slots within the profiles that allow any water ingress to flow to the outside. To ensure an efficient system these slots must remain unblocked. Therefore, periodically, dirt should be removed, drain holes cleared and drainage operation checked by flushing through with water.

Drain hole covers are required for drained or drained and ventilated window systems. These window systems are designed to minimise the amount of water that enter the rebate. The drainage system of the frame ensures the removal of water from the rebate platform.

In timber windows this is achieved by incorporating a sloping platform, a slope of 1 in 10 (6°) is recommended. For aluminium or PVC-u frames, gutters with holes may be used A typical system will include drainage holes at least 8mm in diameter, or slots at least 25mm x 5mm to ensure water escapes. (see GGF Figure 5 for examples).

Ventilation

It is difficult to ensure the removal of all water from the glazing rebates by drainage alone. Water may be trapped, or may be held by surface tension, either as droplets or between opposing surfaces, even though the design should prevent this happening.

Ventilation may be necessary to dry out these areas. This is particularly true of frames with horizontal platforms, or where moisture may collect on the top edge of an IGU. The degree of ventilation achieved is not only dependent upon the size of the ventilation holes or slots, but also upon their position and accessibility to prevailing winds. Slots of 20mm x 3mm can be adequate for ventilation in exposed parts of the window, but further ventilation is probably necessary in more protected parts. To prevent winddriven water being carried into the frame section, all exposed holes and slots should be protected, either by fitting drain hole covers, or by forming the slots in a position in the frame where they are not subject to direct wind and weather.