Build Extension in PEAT soil - Piling or foundation

[hmeah]

I got my planning for a extension approved last year, to build out into the garden from the living room.

I recently did a search and found out on boarholes listing that the area is PEAT. Now i am speaking to builders to do the work but they say 2 metre foundation is all i need, i am not convinced and doing my own research.

If the area is PEAT, would i need piling? I dont want to start the workers digging only to find out i need piling, in which case i would give up on the extension as feel its more expensive.

Is there anyway to know what i would need to do for foundation before giving the work to workmen?

 

[^woody^]

Did your research actually include your back garden or the land from 50 miles around?

Is your house on piles. Are the extensions around you on piles? I can't believe that the buildings around you are built on peat.

Checking your own garden ground is an option.

 

[noseall]

As Woody says, what is the existing build sat upon?

We built an extension onto a bungalow and the existing foundation was a raft. We employed an SE and dug a 2.4m hole for his approval. The ground at the rear of the property (proposed extension location) proved to be ok as it was even further away from the peat location toward the front of the properties and beyond.

All the properties over the road and nearer to the peat area all had 'special' foundations.

 

[Newboy]

Your location profile is London.

Where in London are finding peat?

http://www.landis.org.uk/soilscapes/

 

[JBR]

Some years ago I built a lean-to brick garage. I thought I'd better check with the council inspector and received some good news and some bad news.

The good news was that, although there was some peat down there (according to his records) it was likely to be only a thin seam.

The bad news was that it was six feet down!

I had to dig down to remove it but, fortunately, he was right about it only being a thin seam.

 

[Nakajo]

I'm not familiar with the acronym PEAT. Is it similar to peat?

 

[^woody^]

I'm not familiar with the acronym PEAT. Is it similar to peat?

Just shout PEAT whenever you read this thread.

 

[Chud]

It could have been worse...it could have been Pete #sixfeetunder

 

[^woody^]

PEAT

lol

 

[KenGMac]

hmeah, sorry I have only just seen this thread.

peat or PEAT no matter how it is called it is a real problem, which strangely can occur about anywhere?
I have had Subsidence cases 100m from the Sea, and several dozens of hundred feet up hillsides? even on a sloping hillside, peat occurs in all sorts of unexpected places?

Only way to determine what is down there is a Soils investigation I always ask for a SI to a minimum of 5m, a hand auger will get there no problem.

Next problem is the interpretation of the SI but that is not the thrust of this post.

Even a very thin band of Peat say 200 / 300.mm can and will at times, given the perfect conditions, too much water or too little water [rain] will cause the property to subside

Many, many Years ago I was involved in a make over in a factory in Doncaster, we put in a new concrete floor, it failed, large cracks damaged the floor, a warehouse failed when the large volumes of Steel plate were loaded on to it. the failure was a layer of peat, 200.mm thick at a depth of 3.5 m. the Soils investigation failed to identify it as peat, it was described as soil~? having said that it cost several arms and legs to fix, rip out the damaged Concrete floor, excavate down to remove and replace this thin layer and build up from there.

Every time I find peat, I instruct PILING of what ever sort will sort out the peat without digging it out.

Ken.

 

[Nakajo]

Oh no. First PEAT. Now PILING.

 

[^woody^]

WHAT? EH?

Cant hear you.