Questions About Piling

Sorry another retrospective posting.....

As I mentioned in my post on 19th October we were not able to authorize the piling company to start work straight away because of a couple of queries raised by their estimate. Over the past week I have spoken to their representative, and the structural engineer, in vague terms about these queries, but today I thought it was time to document it properly. I have therefore sent both parties an eMail setting out some questions to which I want some answers.

Firstly, here is the plan of the piling proposal :

The existing house is to the right and piling is not required to the top of this plan (East elevation) because this is where the bedrock is at the surface (the "cliff" at the background of most of my photos).

As you can see, 16 piles are proposed to support the extension and, at the bottom of this plan, the arches beneath the raised patio area.

Here are our concerns and questions, as documented in todays eMail :

• The design of foundation (beam structure, pile size, pile spacing) for the area under the patio arches is the same as for the rest of the proposed building. We would have expected the loadings here to be significantly lower hence a less substantial beam and/or fewer piles would be necessary. Is a beam really necessary here, or could each pier of the arches simply rest on it's own pile ? We really don't want to fill our garden with unnecessary quatities of steel and concrete, and it all has to be paid for.
• A couple of the pile positions marked in the above plan would appear to be on the rock platform (i.e. where the bedrock comes to the surface). It is not clear to us whether or not this has been taken into account. Are piles being deliberately placed in these locations as anchor points for the beam, or has the location of the surface outcrops been forgotten about ?
• While the structural engineer has stated verbally that there will not be a problem with local authority approval for this proposal, we have nothing in writing, or any evidence that they have even been consulted. We cannot proceed on this basis.
• At least a week ago I asked for copies of the calculations prepared by the structural engineer and (eventually) forwarded to the piling company. I have still not received these, so asked for them once more.

Because we have not been party to any of the information between the structural engineer and the piling company, we don't really know who is in the best position to answer these questions, which is why they have been sent to both of them.

We await their response, though I am not holding my breath........