Removing a Chimney Breast: What Steel Support You Need

Chimney breasts eat a surprising amount of floor space, so removing one is a popular job. The catch is that a chimney is a stack of masonry running up through the building — take out a section and everything above it needs supporting, or it comes down.

The bit people underestimate

If you remove the breast in a ground-floor room, the breast on the floor above and the stack in the roof are still there — and they're heavy. That weight has to be transferred into the structure somehow. This is structural work: it needs a structural engineer and building regulations approval, without exception.

How it's usually supported

There are two common approaches, and the engineer decides which is appropriate:

• A steel beam across the opening. The remaining breast above bears onto a beam, which carries the load into the walls each side via padstones or posts. This is the more robust solution and the one most often specified, especially where the load is significant.
• Gallows brackets. Steel brackets bolted to the wall, cantilevering out to carry the breast above. They're cheaper and less disruptive — but they rely entirely on the wall being sound enough, and many engineers and local authorities won't accept them, particularly for larger stacks or questionable masonry. Never assume they'll be signed off.

The other option is removing the stack entirely, all the way up and including above roof level, then making good the roof. That avoids the support question but is a much bigger job.

The party wall point people miss

In a terraced or semi-detached house the chimney usually sits on the party wall — the wall shared with your neighbour. Cutting into or fixing to that wall typically brings the work under the Party Wall etc. Act, which means serving notice on your neighbour before you start.

This catches people out regularly, and finding out afterwards is an expensive mistake. If your chimney is on a shared wall, check your obligations early.

What we do

Once your engineer has specified the support, we fabricate it: the beam cut and drilled to the drawing, any posts and base plates, or brackets if that's what's been designed. Supplied primed and ready for your builder to install, with the documentation building control will ask for.

Frequently asked questions

Can I remove just the ground-floor breast and leave the rest? Yes, that's the usual approach — but only with proper support designed for the load remaining above.

Are gallows brackets allowed? Sometimes — but it isn't your choice or ours. It's the engineer's design and building control's approval, and plenty of authorities decline them.

Do I need to tell my neighbour? If the chimney is on a shared or party wall, almost certainly yes, under the Party Wall etc. Act. Check before work starts.

Got the engineer's drawing? Send it over and we'll quote the steelwork.