Removing a Chimney — When Do You Need Cranked Beams?

Whether you need cranked beams when removing a chimney depends on how much of the chimney you are taking out and from which storey.

Full Removal from First Floor Upwards

If you are removing the chimney breast from first floor level all the way up — retaining the ground-floor breast or removing all of it — then the steelwork picture is relatively straightforward. No cranked beams are typically required. The original structural calculations remain valid, and the installation can proceed as designed.

Partial Removal Creates Complications

Complications arise when you want to retain the chimney breast at one level but remove it at another — for example, keeping the ground-floor breast as a feature fireplace while removing the first-floor breast and the stack above. This leaves a floating section of chimney that needs to be supported, often in an awkward location within the floor void where there is limited headroom and restricted access.

In these situations, the beam(s) supporting the retained upper section may need to be cranked — bent at an angle by a steel fabricator — to fit within the available void space while still bearing onto adequate supports. Cranked beams are not standard stock items; they are custom fabricated, which adds cost and requires careful co-ordination between the structural engineer’s drawings and the fabricator.

What a Cranked Beam Involves

A cranked beam is a steel section that has been cold-bent or hot-bent (or butt-welded at the crank point) to follow a non-linear path from support to support. The joint at the crank is typically a full-strength butt weld, carried out by a qualified steel fabricator in a workshop, not on site. The finished beam is delivered pre-formed and installed in position.

If your project involves a partial chimney removal that requires cranked steelwork, your structural engineer will detail the beam geometry, the weld specification and the padstone positions on the structural drawings.

Asking for a Review

If you are unsure whether your planned chimney removal requires additional steelwork, contact PorthouseDean. We design beam solutions for chimney removal projects across England and Wales, and we can advise on what your specific arrangement needs before any work begins.