Window Types & Parts Glossary

Why These Terms Matter

Knowing the parts of a window makes it easier to describe a problem, understand an estimate and know what’s included in a cleaning. It also helps you tell the difference between something cleaning can fix and something that needs repair or replacement.

Window Glossary A to Z

Double-pane (IGU)

Two panes of glass sealed together with an air or gas gap for insulation. Fog between the panes means the seal has failed.

Low-E coating

A thin, invisible coating that reduces heat transfer. It is usually on an inside surface and should not be scraped.

Tempered glass

Heat-treated safety glass that breaks into small pieces. Common in doors and near floors; it can scratch if cleaned with a blade when fabrication debris is present.

Sash

The movable frame that holds the glass in an opening window.

Frame

The fixed outer structure around the sash and glass, often vinyl, aluminum, wood or fiberglass.

Sill

The horizontal bottom of the window frame, inside or outside.

Track

The channel sliding windows and doors glide along. Sand and grit collect here.

Weep holes

Small drainage openings in the frame or track that let water escape.

Screen / mesh

Fine fiberglass or aluminum mesh in a frame that keeps insects out. Salt air can make mesh brittle.

Spline

The rubber cord that holds screen mesh in its frame.

Muntins / grids

Bars that divide glass into smaller panes, either true divided lights or grids between the glass.

Transom

A window above a door or another window.

Clerestory

A row of high windows near the ceiling line.

Bay and bow windows

Windows that project outward from a wall with several angled panels.

Skylight

A window in the roof, made from glass or acrylic.

Water-fed pole

An extending pole that delivers purified water to a brush head for cleaning high glass from the ground.

Deionized (DI) water

Water with dissolved minerals removed, so it dries on glass without spots.

TDS

Total dissolved solids, a measurement of minerals in water, read with a meter.

Etching

Permanent surface damage where minerals or chemicals have bonded into glass.

Oxidation

A chalky surface on aluminum frames caused by weather and salt exposure.

Related Guides

See cloudy or foggy windows, torn window screens, whether hard water stains can be removed and track, sill and frame cleaning.