Knock through, RSJ, End bearing and SE

Hi,

This is my first post, for a while I have enjoyed reading through many posts and learning .

I have a 3 bedroom end terrace (ground floor and first floor with truss roof), i have had an extension built to the rear of the house via permitted development (external size 3mx7m with vaulted roof). I now want to knock through the back of the house which is a cavity wall (260mm). The opening will be around 6.5m which i know is a large opening.

I have followed all building regulations regarding the build work and have been advised that i require steel calculations for the opening along with padstone spec and end bearing size/length from a structural engineer, which of course i am happy with.

The SE first stated that due to the opening size i may require steel posts on the sides of the opening, i believe he may of changed his mind now (yes not great). Now he is suggesting that the end bearing walls may need to be 600mm each which is not want i want for a open plan space. i have told him that 600mm is too big for end bearing but he is suggesting that I need to pay his quote so he can conduct the calculation to truly determine how much of the wall i need to leave.

I do not have plans as the build work was done on a building notice, however i have attached some pictures and the SE has modified my estate agent plan.

Sorry for the long post, would just like some guidance.

Thank you

Sorry for the double post.

I am happy to change SE if anyone believes that may help, i am in the Leicestershire.

thank you

So he's asking for money up front?

Yes, which I thought was normal.

I do not want to pay the money and the have the SE say that I need 600mm end bearers. I am no expert at all but 600mm seems incredibly large.

It's not normal where I come from but maybe he does that on domestic jobs to avoid chasing clients for payment.

In a roundabout way though you seem to be suggesting that if he can't design out the piers you won't pay him. Anyway better off posting in the Building section, I would hazard most engineers would have a pretty good idea before they did any calcs.

Payment is not the issue.

I rather not waste his time and effort if he believes I need such a large end bearing. I will then have to explore other avenues to use the space.

Thanks I will post in the building section.