Piling for single storey house extension? Help!

[2411Nikki]

Hi,

I'm new to the forum and after some advice and points of view.

I have contracted a builder to build a single storey extension on the back of my house - 7.5m x 3.5m brick build with tiled sloping roof.

They have started to dig the trenches for the foundations but have come across water pretty quickly. The soil is also very sandy. They have stopped work at the moment and have suggested piling to overcome the problem.

They have quoted me a cost of £2400 to do the piling but I'm conscious this may increase once they commence as nobody knows how far down they need to go.

They haven't had any structural engineer involved and we have spoken to building control (private company, not local authority) who also say this is the only way to proceed.

I, myself, have taken it on board to speak to a structural engineer who tells me this isn't the way forward and I would be better rafting.

He is prepared to do a full drawing and calculations (for a fee) to this effect.

In the back of my mind I feel this is the way I should go and present the drawing to my builder who will then be able to give me a fixed cost on extra excavation, waste removal and concrete, etc required.

I would love some advice on this if possible. I'm a bit rubbish with the terminology as I'm not a builder and I am a girl so please bear with me...

 

[jeds]

A raft is a good option - and usually cheaper than piling - as long as the ground is suitable. To be honest, sandy and watery is normally a potential issue because loose sand is easily moved around by water. You need to make sure your structural engineer is fully aware of the ground conditions and ask him to confirm he is 100% happy that it is suitable. Does the £2400 for piling include the ring beam? If it does that's a very good price. Although you are right that they have no idea what the depth is so that price could rise. Piling companies normally provide structural details so you should ask them about that and also press them for detail of what they are offering and what is included.

 

[joe-90]

The original house has been there a while, so why not replicate the house foundation?

 

[noseall]

The original house has been there a while, so why not replicate the house foundation?

Exactly what I was going to ask.

We managed to do strip foundations once in a situation whereby there was a raft foundation on the main dwelling. This was only after consultation and a site visit from an SE and after digging a 2.4m deep hole!

 

[2411Nikki]

Hi,

We had a meeting last night with the builder and he's answered a lot of my concerns. The piling includes the ring beam and he's also offered to fix the price and take the hit if they have to do more work as he's so confident they won't. They are getting structural engineer in early next week and doing tests before they commence. I just hope I've made the correct decision. Biluilding control have now been to site and advised its the best way to go due to ground conditions.

We don't know what the original house was built on but I am in the process of trying to obtain that info from house builder but these things take so long!

Thank you for the advice it is much appreciated.

 

[tony1851]

As jeds, £2400 is a good price,particularly including the ring beam. We did one recently smaller than yours and it was £5K.