Extension has to move, structural engineer query

misc2013

Trying to cut long story short. Ground issues arose at start of our single storey extension build despite trial hole being dug by the engineer and extra foundations designed accordingly. Outcome is we have to move extension across a few feet. Extension will be same but need modifications to roof as a result of new position behind existing house. Builder confident of same, will be a flat roof now instead of original part flat, part elevated. Engineer reckons he needs to do new drawing. Builder of the view this is over the top as modified roof is in fact a simpler structure. Costs are mounting as so far have had to get even more concrete. Originally, engineer would have been signing off on the foundations and the structure. Do we really need new drawings - we're already being charged for his additional site visits and an extra few grand for the extra foundations. If we don't, does that mean we will only get certification of the foundations? We've only started and the costs have shot up. He even suggested new architect drawings but we're definitely not doing that. Surely, if we must get new drawings for modified roof, that doesn't require new architect drawings too. Mind you, our builder doesn't really see the need for a structural engineer at all as it's a straight forward extension but we decided to get one.

DOCARCH

What are the ground condition issues?

Could mini plies be used? Could a raft foundation be used? Could extra deep foundation trenches be used filled with lean mix concrete?

I have come across a lot of poor ground conditions (....and have had to use the above....) but ground conditions have never been bad enough to have to move an extension!

misc2013

DOCARCH wrote: »

What are the ground condition issues?

Could mini plies be used? Could a raft foundation be used? Could extra deep foundation trenches be used filled with lean mix concrete?

I have come across a lot of poor ground conditions (....and have had to use the above....) but ground conditions have never been bad enough to have to move an extension!

We were advised due a particular bad patch that the only option was piling which would cost us 20K.

Anyway, the new foundations are down. I was querying the need for a new roof construction drawing. The extra engineer site visits the past few days has already added 700 to our original 2K bill. He is due to sign off the whole structure but this was with his construction drawings.

We also have to change a window now from the back to the side but think we're OK cos it's approx 9ft from boundary wall. There is currently a small bathroom window there, already in the plans.

shesty

As an engineer myself...get the drawings.
How can he sign off on something that could be a mash-up of his original drawings and the builder's ideas of what will work?

muffler

misc2013 wrote: »

despite trial hole being dug by the engineer and extra foundations designed accordingly.

If Im reading that correctly you paid an engineer for this and it hasnt worked so now he wants you to pay him more?

misc2013

muffler wrote: »

If Im reading that correctly you paid an engineer for this and it hasnt worked so now he wants you to pay him more?

Unfortunately, in a way. Trial hole was dug. But when builders started, they found another area at the boundary wall that had been piled. Extension was due to built along boundary wall. Enter engineer who said it was either pay 20K for piling, move the extension by a no of feet where the ground was better or go for a smaller extension. There was some amount of digging done.For a while, We thought we weren't going to be building anything.

DOCARCH

misc2013 wrote: »

We were advised due a particular bad patch that the only option was piling which would cost us 20K.

I find that hard to believe for just a 'bad patch' that was solved by moving the extension a few feet? BTW that's not aimed at you, I am sure you are just reporting what you were told.

I have done extensions where the entire foundations had to be piled (not just a bad patch) and I think it added around E8K.

There are other solutions to bad patches.

Anyway, what's done is done.

I wouldn't questions your engineers competence/experience, but....

misc2013

DOCARCH wrote: »

I find that hard to believe for just a 'bad patch' that was solved by moving the extension a few feet? BTW that's not aimed at you, I am sure you are just reporting what you were told.

I have done extensions where the entire foundations had to be piled (not just a bad patch) and I think it added around E8K.

There are other solutions to bad patches.

Anyway, what's done is done.

I wouldn't questions your engineers competence/experience, but....

Indeed. We have, since this all started at first trial hole, had 7K approx added to the cost of the foundations. 2 extra loads of concrete I believe. And now the roof has to change cos of the new position of it so he wants to do new structural drawings for the roof.

kieran.

misc2013 wrote: »

Indeed. We have, since this all started at first trial hole, had 7K approx added to the cost of the foundations. 2 extra loads of concrete I believe. And now the roof has to change cos of the new position of it so he wants to do new structural drawings for the roof.

2 extra loads of concrete should not be anywhere near 7k...
Whats a few feet 2-3 or 10-15?

Victor

misc2013 wrote: »

Mind you, our builder doesn't really see the need for a structural engineer at all as it's a straight forward extension but we decided to get one.

Once upon a time, an architect didn't delete something from a drawing that the client decided was an extravagance and shouldn't be built. Architect was a cheapskate and didn't change the drawing. Builder followed drawings. Client had to pony up an extra €100,000+.

Do the drawing. However, you need to have a sit own with the engineer on costs. Who is managing the project?