Building Inspectors - second opinion

ikr2

Hi,

We're having the rear of our semi-detached house extended with a single story sloped roof extension.

At the same time we've had the rear kitchen and dining room knocked together, so the rear of the house will be one large room comprising the extension and the kitchen and dining room.

The architect passed us onto a structural engineer who calculated 2 load bearing steel beams: one to go along the old dividing wall between the the Kitchen and dining room, the other to go above the new opening into the extension where the rear wall was.

These are all in place. Yesterday our Council Building Inspector visited and said they needed a calculation for the sway stability for the remaining masonry left supporting the rear elevation at first floor. This is to confirm that columns under the rear steel are not required.

Our Structural Engineer has responded that most inspectors do not ask for a portalised frame when you remove the rear wall but in this case, it looks like we will have to have a steel goal post arrangement to the rear wall.

So it looks like we are going to have to have the cost and delay of 2 more foundations dug out and 2 more steel pillars constructed and put in??

Is this right? Can our BI insist on this when others do not? Can we get a second opinion? Why isn't the structural engineer doing the "sway stability" calc to prove that we don't need them?

teneighty

It is the structural engineers job to design the steel supports to take all the imposed loads including lateral forces. If you have removed the entire rear wall of the house with no wall piers left then it would be common to have a goal post type arrangement with steel columns either side. If your engineer does not think they are necessary it is up to him to produce the calculations to prove that.


Sounds to me like your engineers has made a serious mistake. Plus your "architect" has been rather lax not to have spotted it as well.

Furts

The pragmatic answer is never fall out with a Building Inspector. Do what they request because ultimately you want a Completion Certificate, so they wield persuasion and power here. It seems what is being requested is required - because your Structural Engineer is not contesting this.

To help sort out matters first ask a simple question - which you may already have resolved. For Buildings Regulations are you on a Building Notice, or are you on Full Plans? If the former then hard luck, if the latter there may be grounds to negotiate.

Bigphil1474

Sounds more like the BI is asking for evidence that columns are not needed - not saying they are needed. If your engineer or architect can't show why they aren't needed, then why didn't they put them in, in the first place. My experience of BI's is that they ask the questions to make sure you can provide the answers, although I deal with temporary structures.

Doozergirl

teneighty wrote: »

It is the structural engineers job to design the steel supports to take all the imposed loads including lateral forces. If you have removed the entire rear wall of the house with no wall piers left then it would be common to have a goal post type arrangement with steel columns either side. If your engineer does not think they are necessary it is up to him to produce the calculations to prove that.


Sounds to me like your engineers has made a serious mistake. Plus your "architect" has been rather lax not to have spotted it as well.

This is exactly what I thought when I read the OP.

It is the BCO's job to approve it to plan, not to specify. He is not qualified to specify. If he is concerned, the SE's calcs should already and immediately allay those concerns.

I cannot think of any reason that a SE would capitulate to a BCO other than in the event that they'd screwed up and by pretending to capitulate it makes the SE look less incompetent.

System

sounds very much like the engineer has made a boo boo here! If they can't prove posts aren't required then there is a huge error in their design, I would be looking at recouping any additional costs from them
(this is a lesson on why it's best to have full regs approval before starting work on site)

ikr2

Thanks for all your advice. After a think we also agreed it was time to go back to our engineer and architect.

Update: the architect said he has never had this before in many years of experience. He is going to talk to the structural engineer to see if he can provide the calculations to satisfy the BI. The architect is not an engineer but reckons the existing nibs should provide required support as in the plans.

Let's hope so.....

Totally agree about getting approval. Somehow the BI didn't have the structural calcs even though our builder did and I was pretty sure they'd been copied in.

teneighty

If you are saying the entire wall is not being removed and small piers/nibs will remain then the steel posts probably aren't needed but the engineer still needs to get his calculator out to prove it.