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Installation - Flashings

Timber window frames require flashings under the sill to stop water migrating to the inside wall linings. Side flashing is also necessary to prevent water migrating to the back of the stiles. Some manufacturers provide a groove in the stile in which to tuck the flashing.

Diagram showing where flashing is installed in a window frame. The following parts are labelled: sash, window head, head trimmer and lintel. The flashing is shown between the window head and the head trimmer.

When the head of a window may be exposed to weather, such as a window in a gable wall, the head of the window needs to be flashed to stop any water getting in.

Diagram of a window set into a cladded wall. Sarking is shown behind the cladding. Jamb lining is shown between the vertical frame of the window and the cladding. Flashing is shown around the opening, and solid metal flashing above the window. Diagram of a window set into a brick wall. From the edge of the opening the following are shown: sash, wind mould, stile, packing, metal flashing strip, jamb stud. The jamb stud runs between plasterboard and building sisal paper.