Steel beams - advice needed!

[Cookie]

Hello!

Our timber frame is going up and is at roof stage. There are 2x steels in the ceiling of the first floor, these both rest on external 140mm walls for support. Those steels are bases for steel triangles which are in the attic/roof space. The 2 main horizontal steels, on the timber framer plans, their ends rest fully on the walls so 140mm end of a steel is on the wall. This is at either end, and the rimboard on the plans is removed in those areas. However, in reality, on site the ends of those steels only rest on the walls at approx 95-100mm and look short. The rimboard is still in place there. The site manager says 100mm is the minimum they must rest on the support wall, so it's fine. Can anyone direct me to the actual building regs which state this? I've searched online and cannot find anything to support the 100mm. (No pun intended!) Thanks in advance.

[George]

You should ask the engineer who specified the steel. 

 

The building regulations are not so prescriptive, however NHBC guidance does specify a minimum of 100mm for steelworks bearing lengths and it is a reasonable rule of thumb

 

https://nhbc-standards.co.uk/6-superstructure-excluding-roofs/6-5-steelwork/6-5-4-installation-and-support/

 

I would have more concern that the wall is being loaded eccentrically but again this would need the engineer to confirm it is OK.

[Cookie]

Thanks, George. The engineer is not coming to look at it, he's instructing from afar as he's the timber framer engineer. I'm suspecting it truly need him onsite to get a proper inspection done.

We actually believe the house is 80mm bigger than it should be front to back, and this accounts for the 40mm discrepancy at either end of the steels. It's a bigger problem  - but the steels' bearing is one aspect I need to add to my arsenal of info!

[George]

Steel fabricators and/or the builder really should be taking site measurements prior to fabrication.  Ditto with the timber frame fabrication.

 

There are a couple of fixes - either needs to be properly approved by the design engineer, the steel extended (site welded if necessary), or the wall altered. Or a combination of these options.

 

I would imagine that the engineer would say it's OK but you need that confirmation from them. This would be acceptable remotely if they have a full understanding of the issue (photos and written record). 

 

 

[Carrerahill]

1 minute ago, Cookie said:

The engineer is not coming to look at it, he's instructing from afar as he's the timber framer engineer. I'm suspecting it truly need him onsite to get a proper inspection done.

Take photos with a measuring tape in place to show bearing length and email over.

 

Depends who made the mistake the if TG engineer and the installer both work for the same company you might find, unsurprisingly, it will be "fine". 

 

The steels should really have been ordered from site measurements to solve issues like this, or an absolute guarantee the build would be done to correct dims and this imposed onto the builder, but even then, things slip. Options may exist to rectify, in fact I am sure they do, but you need to get this looked at properly now.

[Cookie]

Thanks very much for the advice, I'll get back onsite taking more photos and speak to the timber frame engineer. Much appreciated.

[Dave Jones]

150mm is normal bearing for steels, but as George said your probably fine just get signoff from the eng.

[Mr Punter]

With TF 90mm often seems to be acceptable for steel bearing.  Maybe it is because TF used to be 89mm everywhere and still is for internals and party walls.

[Cookie]

22 hours ago, Mr Punter said:

With TF 90mm often seems to be acceptable for steel bearing.  Maybe it is because TF used to be 89mm everywhere and still is for internals and party walls.

Thanks! Measured and they're 85/80mm supported so will have to see what the TF guy says about it!