Adaptability

Steel frames can be adapted more easily than any other structural material, by cutting, welding, drilling and bolting.

Pre-drilling or welding on site and even "clamps" bolted to existing sections can be a much cheaper alternative to demolition of the whole building and reconstruction. Roofs of portal frames have been raised by cutting the columns and fitting extra sections near the bottom where the bending moment is usually least. Double height (6m) buildings can have mezzanine floors added later, providing foundations are adequate or capable of being strengthened.

If a client anticipates that space requirements will need increasing at a future date, then the initial building should be constructed for easy and non-disruptive extension of column-free space, e.g. by using a normal portal in the end wall with gable columns connected to the last portal by slotted connections to allow main portal deflection without transfer of vertical load.

A two-way extension suggests an initial 2-way span grid.

Projecting stub ends of beams can be left for easy attachment of new structurally continuous beams.

Foster and Rogers' Reliance Control at Swindon, where projecting stub ends of beams were left for easy welding of new structurally continuous beams.