Cracks under Steel Beam

[billm]

NHBC state minimum of 100mm but at the end of the day actual bearing should be confirmed by load calculations

Yep, 100mm for a 3m or 5m beam .. but for a 10m beam sat on a 100mm wide vertical padstone ?

BC also pointed out cracks bang in the centre of the blockwork along the 10m beam, so it's flexed in the middle as well.

We'll wait to see what specs he sends to BC and compare with what he fitted. It could be the builder is right and the SE got it wrong .. we'll see

 

[johnny2007]

I've personally never fitted a 10m beam, but on shorter beams (up to 6m) my SE always recommended a minimum of 200mm setting.
100mm might even be compliant, but it's one of those things that's better to over design imo.
For the sake of a few pounds in steel...
And then the blockwork and padstones need to be laid as others suggested.

 

[stevie888]

No. The whole point is not to spread the load, but to prevent local bearing stress shearing the wall directly below the beam.

Why don't lintels require padstones?

Padstones are there to spread the load imposed by the beam out over a sufficient area to match the allowable bearing stress of the masonry. Bigger loads and weaker masonry dictate larger pads..

Perfectly possible to bed a beam direct on masonry if the numbers work. This is why normal lintels don't need pads.

 

[stevie888]

I've personally never fitted a 10m beam, but on shorter beams (up to 6m) my SE always recommended a minimum of 200mm setting.
100mm might even be compliant, but it's one of those things that's better to over design imo.
For the sake of a few pounds in steel...
And then the blockwork and padstones need to be laid as others suggested.

I don't believe for one second that a competant SE has detailed a 100 bearing for such a beam.

I would always have 150 minimum and increase that if the padstone was going to be long to reduce the tendancy for the pad to roll under eccentric loading

 

[^woody^]

Because the local bearing stress does not need to be reduced to an acceptable level by using padstones at a guess?

Yes. But it's bizarre that if you have the exact same opening and loading, and put a steel beam across, building control will want padstones or a calculation on the wall bearing strength. But, if you put a steel lintel across, nothing is required. It's like magic.

 

[Dereekoo]

Yes. But it's bizarre that if you have the exact same opening and loading, and put a steel beam across, building control will want padstones or a calculation on the wall bearing strength. But, if you put a steel lintel across, nothing is required. It's like magic.

Possibly due to lintels have a stated SWL and this puts any bearing pressure with the usual specified 150 bearing within the capacity of even soft brickwork and BC know this, not fact ,just an hypotheses.

 

[Ivor Windybottom]

He said the best way was for him to email my son his concerns and ask for the SE diags / calcs. He has not received any calcs for the job.

He confirmed that as the builder used his own SE then the builder is responsible for the design not my son.

He suggested asking the builder to get his SE on site to inspect and state what the builder has done complies with his SE plans. And we take it from there. Chances are what the builder has built is not the same as what his SE designed. So it's between them to fight it out.

I'm very sure that the builder's SE doesn't actually exist. He's a chancer, he thought he could lob it together on the cheap using fag-packet designs and guesswork.

Find the best possible way of ending this toxic relationship and get someone else in, especially as he's not talking to his own client.

 

[mrrusty]

Find the best possible way of ending this toxic relationship

I bet the payments made are ahead of the goods delivered and work done....

 

[Ivor Windybottom]

I bet the payments made are ahead of the goods delivered and work done....

Probably. Swallow the loss and move on. You can't expect a cowboy to put it all right for free, he won't. He'll cause a load of stress, muck about with it, probably make things worse, then just fail to turn up one day and block your phone number.

Is anyone of the opinion that he's anything other than a cowboy?

Get it built right, learn from it but ultimately forget it.

 

[johnny2007]

As said, I never came across installing a 10m beam, but the last thing I would want is any chance of failure.
It must be installed perfectly and exactly as required by the structural engineer.
Anything else would worry me.

 

[billm]

The builder has been paid in instalments but we've made sure we are behind the line regarding payment for work done and work still to be done. There is still a chunk ££ of the final quote outstanding

I have no idea if there is an SE, if there isn't he's in deep over his head as BC want to see the Calcs. I suspect there is an SE but the build may not comply with the specs he's been given. If the Specs he sends to BC are checked and seen to be inadequate - ie it's SE fault - then I assume he will have to have the specs reworked and resubmitted to BC for checking, agreement and the work rectified accordingly.

As an aside, as there is a crack in the blocks dead centre of the 10m beam, I presume it has sagged. I will measure along it tomorrow. If the beam was correctly specd by an SE, would you expect any sagging at all or non whatsoever ? ie is there an agreed max deflection inbuilt to calcs ?

 

[Dereekoo]

All beams deflect under load , 1/360 or 1/300 span is the general max figure used in BS standards but can be tighter depending on the circumstances i.e. say above a glass partition (extreme case). At 10m the deflection could be 33mm which would be unacceptable in your case and hopefully the beam is sized to a lesser value

 

[Dereekoo]

.

 

[^woody^]

As an aside, as there is a crack in the blocks dead centre of the 10m beam, I presume it has sagged. I will measure along it tomorrow. If the beam was correctly specd by an SE, would you expect any sagging at all or non whatsoever ? ie is there an agreed max deflection inbuilt to calcs ?

If you mean the blocks above the beam, that may not be indicative of beam deflection, as the blockwork would be in compression.

10m is a long span for blocks, so it may be a thermal (shrinkage) crack.

It depends on the type of cracking.

 

[^woody^]

All beams deflect under load , 1/360 or 1/300 span is the general max figure used in BS standards but can be tighter depending on the circumstances i.e. say above a glass partition (extreme case). At 10m the deflection could be 33mm which would be unacceptable in your case and hopefully the beam is sized to a lesser value

That's just for serviceablity though and guidance to avoid cracking to finishes. It does not mean the beam has failed.