Building Control Officer Vs Structual Engineer

[euroman]

I am knocking down an old conservatory at the rear of my house and I'm planning to rebuild on the existing footprint an extension to my existing lounge. It will mean knocking down the wall between etc.

However, I have had a Structual Engineer have a look at the existing foundations of the old conservatory and he believes the existing is capable of supporting new side walls ( full height ) , a 4m span of folding doors and a new flat roof. The old conservatory had planning permision back in 1972. There are no signs of movement or cracks.

Today, the BCO took a look and said it needs a raft foundation. One of the reasons was that there is a lleylandi bush 5m away.
Now I don't really want to do uneccesary work ( ground work so expensive ) and so I believe I could simply cut the lleylandi down?

I'm under the impresssion that if a Structual Engineer says that the foundations are good enough then that's it? They over rule a BCO who then simply puts it down on the file that the SE says all ok?
Am I correct in thinking this?

Last thing I want to do is to upset the BCO but new raft foundations would cost a fortune.

Your thoughts please.

regards

 

[^woody^]

Yes and no.

It is your responsibility to prove to the BCO's satisfaction that what you propose conforms to the regulations.

Just because the SE says something does not mean that the BCO is obligated to accept it, or in fact that it is correct.

Your SE will have to provide sufficient information to substantiate the claim that the foundations are acceptable - ie calculations and ground/loading tests etc

Also the BCO is not able to dicate what work you should do. He can make a suggestion, but can not insist on one solution over another.

Have you seen the other recent thread where the BCO wants 1800mm deep foundations for a a leylandi 6m away? Get your shovel out

 

[euroman]

Thanks for the reply woody.

I was wondering if I could simply just cut down the lleylandi bush? It's about 2m high x 0.8m wide and just about 5m to the trunk away. I understand about heave etc but this is just a small bush/tree.

The SE and my builder believe the foundations are sound and the calcs ensure they're adequate. I don't mind getting my shovel out but I would rather get my saw out instead!

 

[^woody^]

Yes definately go for the saw!

Look at the thread "1.8m Foundations" posted recently, as its got details of what will or could happen to the ground when if a tree is cut down.

 

[noseall]

i did a job for a structural engineer living in Chiswick. he had some funny ideas!

laminated timber lintels, e.m.l/ render/insulation walling, huge patio doors. nightmare.

the point is, he was able to prove that the unusual structural situations all conformed to, or satisfied building control requirements.

the b.c.o's chief engineer was always down at our Chiswick address. listening to the pair of them arguing and the customer coming off better was a treat.

 

[Shytalkz]

BCOs will usually - and rightly - defer to an SE: BCOs are not structural designers, they are enforcers of technical regulations; and they do not attract liability as an SE does, if it all goes Pete Tong.

They know their place up here in carrot land.