Large cracks in wall above steel beam and in chimney breasts

23 May 2019
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United Kingdom

We had 3 steel beams inserted (about 5m long) across the middle of the house on the ground floor as we had two chimney breasts knocked out yet they remained on the first floor in the bedrooms so required extra support.

We’d be mad to not expect any cracking however, the cracks are larger than we expected and the plaster now bows out above the crack indicating potential cracking to the actual brickwork behind the plaster not just to the plaster. The worst cracks are to the supporting wall above but there is also cracking in the chimney breasts.

Appreciate any advice on this



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Manchester9100, good evening.

That looks "nasty" [sorry about that] but on this site yes there are loads of posts regards "Cracks" most can be explained away as thermal or something relatively simple, your images are way above that.

When was the work completed??

Was there a Structural Engineer involved?? did he "sign of" the completed installation.

Bluntly If i walked in on what you have, my reaction is that there is something on the move!!

Sorry if I sound alarmist, but? I have been working as a Subsidence Specialist for several insurers for over 10 years?? need I elaborate??


Thanks for the reply. Structural calculations were provided and building control have come to check the steel and said it looked ok however they did not look upstairs at all.

I’m trying to get the structural engineer back out who initially scoped for the calculations however he’s being reluctant to do a site visit and I feel like I can’t articulate it properly over the phone.

Do you have advice on next best steps to rectify the situation and make sure it’s safe?

I'm certainly no expert but I've done a few chimney breasts and would suspect your issue is more likely one of workmanship - either the support for the ends of the steels (but this should have been checked by Building control) or far more likely the packing between the top of the steel and bottom of chimney breast - on my last one the BCO barely looked at this, just asked if I'd packed it with slate.
I would get the builder back. In the meantime you might see a bit more if you remove the skirting board from in front of the chimney breast.
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My initial though was poor packing under the beam.

Steels do have some deflection under load, but that would probably cause a bit of cracking immediately.

I dont suppose the SE wants to visit because theres probably nothing for him to see -all the structural element is now hidden. I guess he could advise whether its safe or not and how to monitor it.

The cracks are tapered -whichs makes it clear something has dropped.

What age is the house -what condition are the walls that support the steel? Whats the foundation like on the house.

Either the wall sitting on the steels has dropped because it wasnt tightly packed, or the wall that the steels are bearing on has dropped.
I’m trying to get the structural engineer back out who initially scoped for the calculations however he’s being reluctant to do a site visit and I feel like I can’t articulate it properly over the phone.
Tell him to come out quickly or provide you with details of his liability insurers. Do the same for the builder. Don’t expect much help from building control.

That work is bad and is not in the category of "expecting a few cracks".

It may be related to the beam design - beams can be calculated to be sufficient to support walls etc, but there is another calculation that should be done to ensure that cracking of finishes such as plaster does not occur. If he's made a mistake on this then this can happen, but the thing still be safe. Whilst a proper structural engineer will rarely make mistakes, someone with a computer programme and half a clue may.

The other option is poor installation. Some inexperienced builders may lift the walls up with the supporting props, rather than just support them in place and this causes cracks. Or more commonly they don’t pack the walls or fill gaps caused by dropped bricks, and this allows the walls above to drop.

If none of them admits liability, and there is liability there make no mistake, then you may need to instruct a third party “expert” to report on it – another structural engineer. Your house insurers may be able to help with advice, costs or take the matter up on your behalf.
Hi everyone thanks so much for the replies really helpful. The wall above the steel is rubbish to be honest, the property is a Victorian semi built in 1910 and as we had architraves replaced above the steel we saw the wall above back to brick (attached images) here you can see lack or mortar and that it’s ofren packed with buts of wood. I guess if this is the wall above and it lacks integrity and dropped this is why?

I didn’t know my builder would be responsible for making sure the bricks above in the chimney breast were put right, he just said to expect cracking and they could plaster over it, but as well have a baby in the room above I really want to ensure it’s put right, that same wall also supports a loft room above.

The steels we’re put in on accrows three/four weeks ago then put on padstones a week later.

Thanks again


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As others have pointed out, beams do deflect but the trick is to design the beam so that the deflection is minimal and does not lead to excessive cracking as your has.
Can you upload images of the calculations your SE has done (with your address blanked) so we can see what allowance has been made for deflection?
This can sometimes give a clue as to where responsibility lies.
Hi all

Structural engineer coming Tuesday. Does anyone have any idea on how to repair this? This wall supports the loft bedroom above so would appreciate any advice on remedial work to make it safe, especially if the brick work has dropped... at the moment less interested in liability and really just want to get it fixed so we can be assured no movement will continue to happen

Thanks again
Yes appreciate this, do you think if we strip the plaster fully back from the wall this will help us identify the cause?

It will need replastering anyway, so you may as well remove it now so that the SE can see the cracks beneath. Sometimes softer plasters can hide the true extent of the cracking in the brickwork.
Hi all

We’ve now had the plaster ripped off so can see what happened behind. Big crack in actual brickwork. Waiting for structural engineer to come back to us but in the meantime any ideas of remedial work to make right?

Thanks again everyone this has been really helpful


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Impossible to say without seeing the whole picture - is that a chimney breast or is it a wall (internal or party wall)?

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