Removal of internal wall - could structural engineer be wrong?

[Artair]

Hello,

First of all sorry for the long post. I wanted to try and include as much info as I could.

I have an internal brick wall that I want to knock down in my bungalow. The ceiling joists run parallel to the wall in question, but one appears to run along the top of the wall. There is a ceiling binder than runs perpendicular to the joists/wall, and it seems like this binder gets it's support from the wall (in addition to the hanging from the rafters). Here is an example of what appeared to be going off when I looked in the loft space.


Suspecting the wall may have been structural I employed a local structural engineer to take a look and he came to the same conclusion, so he calculated a steel beam for me.

Today I started to work on taking the wall down and chipping away at the render/plaster along the top where the beam will go. I didn't get far when I discovered that the ceiling joist we thought sat on top of the wall actually doesn't. The wall itself finishes 30-40mm below the joists in some places and the joists (there are two) aren't even directly above the wall, thy are offset. They 'float' above the wall on either side of it with the plasterboard ceiling hanging from them, and the gap between the ceiling and the top of the wall is just filled with render. Thus, the wall doesn't appear to be offering any kind of structural support to the joists or binder.

Here is a quick sketchup drawing of what is actually going off.


As you can see, the joists don't sit on the wall but actually sit on the render (with plasterboard sandwiched between). My question is, what do I do now? I have already purchased the steel and notified BC, and if I was to continue as planned and use the steel, then the joists either side of the wall would be half on/half off the steel (see example below). I don't know if that is likely to be passed by BC as I would have expected the joist to have to sit wholly on the steel.



My preference has always been to not have to use a steel and from what I can see now, it may appear that might not have to. I will be speaking to the SE on monday to see what his thoughts were but I just wanted a second opinion before I did. If the SE agrees that a steel is not required, can I retract my building notice and (hopefully) get a refund or is it likely the BC will still want to come and inspect?


In the last picture there, the top of the wall is level(ish) with the top of the chipped render. I haven't broken any of the wall away there, I just tapped at the render and it fell away exposing the void behind it.

Thanks

 

[^woody^]

If the wall is not touching the joists, then the beam can be omitted.

Alternatively, you could put a timber beam in the loft and strap the binder to this.

 

[CambridgeBrummie]

I am presuming the roof construction is a "cut-roof", ie individual rafters, ceiling joists, binders and purlins.

If it is, then I would not expect the ceiling binder to span much more than about 2.5m between supporting structure, unless of course it is actually a nominal tie and the ceiling joists are spanning the full length between supporting structure.

Are you able to post a plan giving overall dimensions and spans of each component.

I agree it looks like there is no support provided by the wall, but ceilings have been known to hang in catenary mode for many years!

By the way, have you checked that artexed ceiling for asbestos??

 

[Artair]

Hi, thanks both for your replies. It's good to know that I may be able to do away with the steel.

It is a 'cut roof' as you suggest. I have attached a plan showing the dimensions of the room. The ceiling joists are 95mm x 45mm (approx) and span 4.86m max. The binder is smaller at 100mm x 35mm (approx), and spans the full width of both rooms at 5.65m with seemingly no support from the wall.



The binder does however hang from the purlin/rafters as in this example http://gapfilla.com/images/D-images/roofpitched.gif. There are three hangers evenly spaced along the length of the binder.

Cheers

 

[^woody^]

The engineer is wrong then.

 

[Artair]

That's what I suspected, though to be fair to him from above it did look like one of the joists was sat atop the wall, but it was actually sat on render and not the wall itself.

I have spoken to the engineer now anyway and he agrees that the wall is offering no support, based on what I have told him and the pictures I have sent him. The only problem I have now is that BC already have a copy of the engineers report. Are they likely to still insist on the steel, even if they saw the situation for themselves, because that's what the report says?

I've asked the engineer if he will redo the report to say no steel is required, but I am waiting to hear back from him re cost as I expect he will want to see it himself.

Thanks again.

 

[^woody^]

No. The council only need engineer's reports to justify that their beam is adequate. The council's function is merely to check that the work conforms to the building regulations, not whether the building regulations actually apply or not.

You could now withdraw the application, as there is no structural work involved. Tell them it's a mistake, or better still (and easier to explain) that you are not going ahead with the work. This might get you a refund, in full or in part. You don't need a revised report from the engineer.