What is a door frame spreader?
A door frame spreader (also called a transit bar or temporary sill) is a batten or strip fixed across the foot of a door frame to hold the two jambs at the correct distance apart during transport and installation. Interior door frames usually have no real sill because the floor runs through, so without it the feet of the jambs would be loose. In Dutch this is called a steldorpel: a temporary sill used while “setting” (accurately positioning) the frame.
With steel door frames the timing for removal depends on the product. Some manufacturers’ instructions say the bars must come off before fitting powder-coated frames, while on primed frames they may stay as a fitting aid and are removed afterwards. On some frame types the spreaders stay until the mortar backfill has dried.
In Dutch the word has a second meaning: a batten under a real sill that holds it at the right height and position, and stays in place permanently.
Application
- Read the fitting instructions. They tell you whether the spreader comes off before or after installation.
- Check the width at the head too. The spreader only fixes the bottom. Measure the opening at the top and middle, and use a temporary brace if needed.
- Check plumb and level. Set both jambs with a spirit level or laser.
- Allow for the floor build-up. Frames often stand on the structural floor, with screed and finish laid later. Set the height to the agreed datum.
Common mistake: removing the spreader too early. When the frame is packed or backfilled, the jambs get pushed inwards, and the door binds or the gap around it becomes uneven.
Related terms
- Interior door
- Threshold
- Door sill
- Hanging a door
- Door clearance
- Window subframe
Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.