Mullion

A removable vertical substrate permitting the widening of a door set to either feature an additional door leaf or a sidelight. An alternative to a nib / partition wall between separate door sets, the space and cost involved in this is minimised by the extension of a singular frame to allow for additional door leaf(s). The width of such an opening would not otherwise be possible as the door leaf width is restricted by manufacturing capability, the greater its width and weight places more stress on the frame and a wider door leaf covers a greater swing space.

This framing component is utilised for the following purposes:

Extending Door Set Width (including Fire Doors)

The fitting of a mullion frame creates an internal support for the widening of the over wall. This can create an additional walk-through opening with the fitting of an extra door leaf. The fitting of a mullion for this purpose is tested and certified with Spence Doors' 2-Hour Fire-Rated Door Set. This permits the lateral dimension of the doorset beyond the standard 2700mm width. This is particularly useful is spaces that require Fire-Rating but are also subject to heavy traffic passing through or large goods to be transported through.

Fitting an Sidelight

The space alongside the door created by a Mullion framing piece is an opportunity for natural lighting to pass through. The fitting of an sidelight can achieve this whilst adding a distinctive architectural feature to the door.