Pile and Beam Foundation Costs?

[Sdfuk]

Hi

I'm looking at getting an orangery built at the back of the house. The area will be approximately 4m x 8m. Unfortunately, the soil isn't great (clay) and a soil report we had done recommended going down to a depth of 5m.

We will also have to have a drain moved further away from the house. I know that you can get a double sealed cover but I'd rather it be on the outside of the building if any blockages occur.

Any idea of what costs I'm looking at?

many thanks
S

 

[noseall]

a soil report we had done recommended going down to a depth of 5m.

5m!!

Not a clue about costs but gathering from some of the posts on here there is rarely change out of £6k for a modest extension.

Mucking about with the drain pipe will seem like a doddle in comparison and should cost a few hundred quid to alter depending upon depth and access.

 

[Sdfuk]

Hi

Thanks. Yes, 5m is a pain but one part of house has had subsidence, all sorted years before we bought the property. I've seen similar situations being costed at around 8-9k.
We're expecting some quotes back soon so will let you know (may be useful for others to).

Cheer
S

 

[RonnyRaygun]

Hi

Thanks. Yes, 5m is a pain but one part of house has had subsidence, all sorted years before we bought the property. I've seen similar situations being costed at around 8-9k.
We're expecting some quotes back soon so will let you know (may be useful for others to).

Cheer
S

What is your house built on that means you have to go 5 metres deep? Is it 5m to the first sign of good soil (i.e. non made ground)?
Piles need to be designed for the ground conditions and the loads anyway, so 5m is nothing more that a vague estimate and it could be deeper.

 

[theoldun]

Had no piling done for last 6 years , but to pile and RE 600mm wide ring beam over 32m2 footprint, we would budget for 11k inc and hope to get it done at about 9k inc. Lot will depend on width of access, size of rig and type of pile. Most mini rigs with 750mm width will suit your requirements.
Regards altering drain run, providing you have sufficient fall on existing drains to divert round new extension, we would budget for 1000 notes for four new manholes and approx 16m dig and pipe.
Note your post Ron. If the OP has had a sub soil analyst report from a reputable company, they would either have hand or power driven an auger core sample tube down 5m and prepared report accordingly.
Regards oldun.

 

[RonnyRaygun]

double post

 

[RonnyRaygun]

Note your post Ron. If the OP has had a sub soil analyst report from a reputable company, they would either have hand or power driven an auger core sample tube down 5m and prepared report accordingly.
Regards oldun.

Yeah, I realise that's probably how they've taken their soil samples, but they are ground investigation experts, not pile designers. They can't accurately predict the required depth of the pile without designing it.

 

[Sdfuk]

Hi

Thanks for the responses.

Just got one quote back.

design A (4mx6m) = £12.5k.
design B (4mx9m) = £15.5k.

Re the soil report, they say the following (summarised as much as possible).

"The investigation comprised one borehole taken to a depth of 8m. The geology was found to be initially soft to firm silty clay over stiff to very stiff clay at a depth of 4.8m and live roots to a depth of 3m. Nearby vegetation has dried the clay to a depth over 4m and extends to a depth approaching 5m.

The minimum (pile) foundation depth will be 5m. Precaution against the affect of heave should be incorporated in to the design and construction in case the clay rehydrates in the future".

"A suspended ground floor slab over a ventilated void will be required".

Just a quick (noob) question, do all piles have anti-heave or is this something extra that you add? I do know a local builder who estimated a cost of at least double of those above. Is this because of a different pile design?

Cheers
S

 

[Deluks]

Thanks for the update.

Just a quick (noob) question, do all piles have anti-heave or is this something extra that you add?

I believe anti-heave would be for the groundbeams. Shouldn't add much to the time/cost.

I do know a local builder who estimated a cost of at least double of those above. Is this because of a different pile design?

It's because he's 'just' a builder, and didn't have the full facts regarding the ground, or the technical design know-how to come up with a proper design. And it was after all, an estimate.

 

[Sdfuk]

Hi

To be fair to the builder I know, he was the guy who advised me to have the borehole done and received a copy of the results. He also does a lot a pile foundations as the area we live in is really bad re foundations.

A House was recently built near to us and I was amazed at how deep they went with the foundations, something like 10m.

I've got prime oak coming back to me soon with a price. They have a copy of the soil report so should be interesting vs costs above. Will post ASAP.

Cheers
S