Door size
Oversized or double-leaf sets typically add £900–£1,900 each through heavier fabrication, additional ironmongery and reduced installation output.
Fire performance
An FD60-rated assembly generally adds £350–£750 each compared with a standard non-fire-rated doorset.
Security rating
Certified security construction, upgraded locks and reinforced frames can increase the rate by £800–£2,500 each.
Ironmongery
Panic hardware, access-control preparation, closers and specialist locking can add £250–£1,200 per doorset.
Opening condition
Packing, trimming, local making good and irregular existing openings commonly increase installation cost by 10–25%.
Finishes and glazing
Bespoke colours, marine-grade coatings, vision panels or louvres can add £250–£1,500 each depending on specification.