Advice please - Piling for an extension.

pacific · 5 Jan 2013

To be able to build a kitchen/diner extension on the back of our house, we have to have piled foundations. We live in a clay soil area of Essex and have a large mature Oak and Ash tree with TPO on them, that will be approx 30ft and 80ft from the extension, plus a hedge of Leylandii, in the garden.

We have had three quotes for piling, one is for a Pileraft system. The extension will be single storey, flat roof, approx 6mx5m. They are saying it is about 10 days work and the costings are coming in at about £15,000.

They are quoting on 30m2 of reinforced concrete foundation slab with 10 250mm dia open bore holes with 3.0, cardboard anti-heave sleeves.

We were very shocked at the prices and wondered if we are approaching the right companies!

Can anyone tell us what we should expect to pay for Piling?

Also we have noticed through looking online there are companies that do piling and some do mini-piling, what is the difference?

With a builders quote we have had and the piling quotes, we are looking at about £60k which means the extension is not going to happen!

We have now wondered if there is any alternatives to building the extension. We wondered about a timber framed extension, but I have read on some forums this can be a problem with resale of property.

Can any one help?! Thank you.

JMSD · 6 Jan 2013

Was this advised by an engineer or your Building Control Officer?

Piling is expensive and there might be alternatives:

Firstly you could look at how deep a traditional strip footing would have to be based on the NHBC method in the chapter on building near trees.

If strip footings would have to be so deep that they are not practical or economical to construct (I guess that whoever is advising you has already looked at this and reached this conclusion) than piling might be your only option. There are alternatives to a piled raft though. Using a piled ground beam instead might reduced the number of piles (10 sounds a lot) as well as the reinforced concrete work. You would need a suspended ground floor in this case though (perhaps beam and block) and this needs to be ventilated so you would need to consider if it will work with the external level.

There are lot's of different types of piles. Screw piles and driven small diameter steel piles (Grundomat) are often used as cheap alternatives to cast in-situ concrete piles in domestic situations if they can provide the required load capacity. They would also need to be sleeved.

pacific · 6 Jan 2013

This was advised by our architect. The planning has been approved on this basis. Houses either side of us have extensions, one single storey, one two storey, built 10 and 16 years ago. Neither had piling done, and neither have had problems with them, and we all have large mature trees within similar distances. Don't know if regulations have changed since their extensions were built.

We are considering speaking to a structural engineer to see what they think, although we are aware they can be overly cautious.

We will look in to your suggestions, thank you for the advice.

RonnyRaygun · 6 Jan 2013

JMSD said:
Firstly you could look at how deep a traditional strip footing would have to be based on the NHBC method in the chapter on building near trees.

The Ash wouldn't be an issue at 80 feet away, but the Oak could mean strip footings deeper than 2.5m if high volume change soil.

JMSD said:
There are lot's of different types of piles. Screw piles and driven small diameter steel piles (Grundomat) are often used as cheap alternatives to cast in-situ concrete piles in domestic situations if they can provide the required load capacity. They would also need to be sleeved.

I've specified Grundomats on a couple of jobs. They are great where access is tight as no rig is required and plant can remain out in the road. They don't carry much load, but can be grouped pretty close together due to their small diameter (as little as 100mm).
Then you've just got to sling some beams between them!

limerockconstruction · 6 Jan 2013

I’m about to start digging on a job where we have an oak covered by the TPO.

Originally it was going to be a pilled solution, but it made the whole thing seem more unaffordable, so the customer dug a trial pit were the rear foundation was going to be situated and then got the council and an arboricultural consultant out to sign it off to say that there weren’t any main roots through the area.

They then changed the solution – it’s a double storey to the side – so the new side foundation (strip) is going to be 2.5 running to 2.7m deep – at the back we are then going to pour an insitu cast ground beam off of the top of the new foundation to the existing house foundation and sling block and beam between….seems reasonably sensible to me.

The customer was adamant he didn’t want to pay for piles.

jeds · 7 Jan 2013

pacific said:
This was advised by our architect. The planning has been approved on this basis.

Piling isn't a standard foundation method - it's a solution to a problem. Your architect either had a reason for advising piling (i.e. to solve a problem) or he's an idiot. ( I know what my money's on.) You should ask him exactly what the reason was. If he can't come up with a reasonable explanation revert to a standard strip. Planning has nothing to do with it - they aren't concerned with how you build your extension.

hamazz · 29 Jan 2013

my 2 cents worth

i had a hawthorn tree 5m away from where we were going to build an outbuilding, building control said 2.5m + or pile it.. as we are building upto the boundary fence dont really want to dig that deep and have anything collapse. looked at piling had a few quotes back, the cheapest at about 2500, the highest at about 12000. it is probably cheaper to have the piles steel cased driven as opposed to augered, as if they hit a void or water when augering they need to start a new hole. the price of 2500 was for 6 piles 250mm 6m deep, the breakdown was 1000 for mobilisation to site, then 200 per pile and a few other costs, this did not include the ring beam. the ring beam alone with full anti heave was around 5800, most companies run a rate of about 150-200 per lm or ring beam, i can do this myself for less than half the cost, you can get pre-fabricated sections of rebar cages etc and pre bent bars from places like brc or lemonground works, and putting it together will probably take a day or so but worth the savings. if you want the name of the piling company pm me, and i can give you a list, as i originally got about 8 companies to quote for the works

hamazz

indus · 31 Jan 2013

I find it difficult to believe that you need £15ks worth of piling for a small domestic extension, something doesn't add up.

There must be a cheaper solution. Digging deep strip foundations is nowhere near as expensive as some people make out.

Or perhaps steel beams and padstones? My friend (also lives in Essex btw, Epping) has just had this done for a large double storey extension.

I had a single storey (solid construction, block, brick, pitched tiled roof) outbuilding built about a year ago. This was within a few metres of a number of large trees and I have clay rich soil.

Though it didn't need BRegs approval I paid for an engineered solution for the foundations and again it was padstones and steel beams. It wasn't expensive.

hamazz · 1 Feb 2013

indus

its interesting you brought that up, as i was thinking of doing that rather than piling, my room is 8.6 * 3.5, i was going to put 6 pad then rsj beams encase in concrete over them.
can i ask how deep you dug the pads? and how much the design cost you? and whether it worked out the same cost as having it deep trench or piled??

hamazz

indus · 1 Feb 2013

Hi Hamazz, my outbuilding is a similar size ie about 7.5m by 3.5m. There are 6 padstones with clayboard to the sides and bottom, and then steels shuttered in concrete.

IIRC the padstones were 1mx1mx1m. I'll double check the drawings if I can find them.

In terms of cost I don't know what the groundwork cost separate to the whole build. However when I spoke to the builder at the time he said it worked out about the same as trenches ie what you saved in excavation costs with pads/steels you paid out in steel costs.

My builder was a little short of work at the time and so I got it done at a good price. I paid £17k for it so £650/m2, I don't think the builder made much from it but he just wanted to keep his boys in work until the next job came along.

It has been done to a very good standard and has

1) Brick, cavity, block walls

2) Double pitched tiled roof

3) One single door, one patio doors, and two windows, all double glazed.

4) Electrical supply and spots. No water/heating of course as it's an outbuilding and not for habitation.

5) Screed floor

6) Internal walls plasterboarded and skimmed.

I'll take some photos of the finished item tomorrow if the weather is ok.

Good luck

peterperfection · 1 Feb 2013

pacific said:
To be able to build a kitchen/diner extension on the back of our house, we have to have piled foundations. We live in a clay soil area of Essex and have a large mature Oak and Ash tree with TPO on them, that will be approx 30ft and 80ft from the extension, plus a hedge of Leylandii, in the garden.

We have had three quotes for piling, one is for a Pileraft system. The extension will be single storey, flat roof, approx 6mx5m. They are saying it is about 10 days work and the costings are coming in at about £15,000.

They are quoting on 30m2 of reinforced concrete foundation slab with 10 250mm dia open bore holes with 3.0, cardboard anti-heave sleeves.

We were very shocked at the prices and wondered if we are approaching the right companies!

Can anyone tell us what we should expect to pay for Piling?

Also we have noticed through looking online there are companies that do piling and some do mini-piling, what is the difference?

With a builders quote we have had and the piling quotes, we are looking at about £60k which means the extension is not going to happen!

We have now wondered if there is any alternatives to building the extension. We wondered about a timber framed extension, but I have read on some forums this can be a problem with resale of property.

Can any one help?! Thank you.

They are taking the p! $ $ as most London area chancers do.
Piling is easy peasy and quicker than conventional foundations. Less materials too.

I hate these firms who try to stuff consumers. Regional difference is no difference concerning materials- although- Labour is crazy.

peterperfection · 1 Feb 2013

indus said:
Hi Hamazz, my outbuilding is a similar size ie about 7.5m by 3.5m. There are 6 padstones with clayboard to the sides and bottom, and then steels shuttered in concrete.

IIRC the padstones were 1mx1mx1m. I'll double check the drawings if I can find them.

In terms of cost I don't know what the groundwork cost separate to the whole build. However when I spoke to the builder at the time he said it worked out about the same as trenches ie what you saved in excavation costs with pads/steels you paid out in steel costs.

My builder was a little short of work at the time and so I got it done at a good price. I paid £17k for it so £650/m2, I don't think the builder made much from it but he just wanted to keep his boys in work until the next job came along.

It has been done to a very good standard and has

1) Brick, cavity, block walls

2) Double pitched tiled roof

3) One single door, one patio doors, and two windows, all double glazed.

4) Electrical supply and spots. No water/heating of course as it's an outbuilding and not for habitation.

5) Screed floor

6) Internal walls plasterboarded and skimmed.

I'll take some photos of the finished item tomorrow if the weather is ok.

Good luck

Us northern builders should pop down south and show them what real value for money is .
A few weeks in the Savoy and a few hours every day on the job. Job done- and to a very high standard . No messing no boolshirt -- just quality .

peterperfection · 1 Feb 2013

pacific said:
To be able to build a kitchen/diner extension on the back of our house, we have to have piled foundations. We live in a clay soil area of Essex and have a large mature Oak and Ash tree with TPO on them, that will be approx 30ft and 80ft from the extension, plus a hedge of Leylandii, in the garden.

We have had three quotes for piling, one is for a Pileraft system. The extension will be single storey, flat roof, approx 6mx5m. They are saying it is about 10 days work and the costings are coming in at about £15,000.

They are quoting on 30m2 of reinforced concrete foundation slab with 10 250mm dia open bore holes with 3.0, cardboard anti-heave sleeves.

We were very shocked at the prices and wondered if we are approaching the right companies!

Can anyone tell us what we should expect to pay for Piling?

Also we have noticed through looking online there are companies that do piling and some do mini-piling, what is the difference?

With a builders quote we have had and the piling quotes, we are looking at about £60k which means the extension is not going to happen!

We have now wondered if there is any alternatives to building the extension. We wondered about a timber framed extension, but I have read on some forums this can be a problem with resale of property.

Can any one help?! Thank you.

I JUST RE-READ THIS .
60K FOR A PIDDLY EXTENSION ?
YOU GOTTA BE KIDDING

Oh-- how I wish I had have lived down south . I could have been a millionaire 30 years ago instead of 10 years ago.

peterperfection · 1 Feb 2013

indus said:
I find it difficult to believe that you need £15ks worth of piling for a small domestic extension, something doesn't add up.

There must be a cheaper solution. Digging deep strip foundations is nowhere near as expensive as some people make out.

Or perhaps steel beams and padstones? My friend (also lives in Essex btw, Epping) has just had this done for a large double storey extension.

I had a single storey (solid construction, block, brick, pitched tiled roof) outbuilding built about a year ago. This was within a few metres of a number of large trees and I have clay rich soil.

Though it didn't need BRegs approval I paid for an engineered solution for the foundations and again it was padstones and steel beams. It wasn't expensive.

I REALLY CANT BELIVE THE SIZE OF THOSE STEELS .

Someone is taking the pee--no wonder builders get a bad name .
regarding why the piling was advised - look at original post .
Clay/soil ?

DIFFERENTIAL MOVEMENT OF GROUND- PILING IS ONLY/SENSIBLE ANSWER.
I could send up a team of first class guys to doit- no messing no fuss and no 'rip off'.

ps-- I just noticed the people stood there watching !!.

Says it all .
Like Gracie Fields said-- Singh as you go- 'watch the world go by'.
what the f00 k is this country coming to ?.

indus · 1 Feb 2013

peterperfection said:
indus said:

I find it difficult to believe that you need £15ks worth of piling for a small domestic extension, something doesn't add up.

There must be a cheaper solution. Digging deep strip foundations is nowhere near as expensive as some people make out.

Or perhaps steel beams and padstones? My friend (also lives in Essex btw, Epping) has just had this done for a large double storey extension.

I had a single storey (solid construction, block, brick, pitched tiled roof) outbuilding built about a year ago. This was within a few metres of a number of large trees and I have clay rich soil.

Though it didn't need BRegs approval I paid for an engineered solution for the foundations and again it was padstones and steel beams. It wasn't expensive.

Click to expand...

I REALLY CANT BELIVE THE SIZE OF THOSE STEELS .

Someone is taking the pee--no wonder builders get a bad name .
regarding why the piling was advised - look at original post .
Clay/soil ?

DIFFERENTIAL MOVEMENT OF GROUND- PILING IS ONLY/SENSIBLE ANSWER.
I could send up a team of first class guys to doit- no messing no fuss and no 'rip off'.

Peter, I'm not sure what you are talking about. What is wrong with the size of the steels? Too big, too small?

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Advice please - Piling for an extension.

Similar threads