A window frame (or door frame) is the timber, plastic or aluminium framework installed in a wall to hold a window or door. The frame forms the fixed surround in which the opening part (the window sash or door leaf) is hung. It is the connection between the wall and the glazing.
Components of a frame
A frame consists of four main parts:
| Component | Position | Function |
|---|---|---|
| Head | Top | Horizontal member at the top, rests on the lintel |
| Sill | Bottom | Horizontal member at the bottom, drains water away |
| Jambs | Left and right | Vertical members on each side |
| Rebate | Inner edge | The step in which the window or door sits |
On a window frame there is often also a drip edge (weatherbar) on the sill: a sloped edge that directs rainwater away from the frame.
Types of frames
Timber frame
The traditional choice. Easy to work, paint and repair. Requires maintenance (repainting every 5-7 years). Widely used in renovation and self-build projects.
PVC frame
Maintenance-free and good insulation. Cannot be repainted in a different colour (unless specially treated). Popular in new-build construction.
Aluminium frame
Slim profile, strong and maintenance-free. More expensive than timber or PVC. Often used in modern architecture.
Installing a frame in a garage or renovation
When building a garage or renovating an existing building, the frame is an important component:
1. Measure the rough opening — The opening in the wall where the frame will go. Always measure at multiple points (top, middle, bottom).
2. Check the rebate size — The rebate size is the measurement of the glass or panel that fits in the frame.
3. Place the frame in the opening — The frame is set into the opening, aligned level and plumb.
4. Fix in place — With frame screws or plugs into the masonry.
5. Finish — The gap between frame and wall is sealed with sealant and finished with a trim strip.
Shimming space
Between the frame and the wall there should be 5-10 mm of shimming space. This gives you room to level the frame, and is afterwards filled with PU foam and sealed.
Measurements and terminology
- Rough opening — The size of the opening in the wall (reveal to reveal)
- Frame size — The outer measurement of the frame (slightly smaller than the rough opening)
- Rebate size — The size of the glass that fits in the rebate
- Shimming space — The gap between frame and wall for alignment
Common mistakes
- Not installing level — A crooked frame means windows and doors will not close properly
- Too little shimming space — Without shimming space you cannot align the frame
- Sill not draining — If the sill is flat, water pools and the timber rots
- No drip edge on the outside — Water runs down the wall instead of dripping away
Related terms
- Lintel
- Rough opening
- Rebate size
- Glazing
- Drip edge