Might need piles and planning question

[mickmcpaddy]

I'm considering building an extension on the back of my house, the original house is about 15 years old and is built on a concrete raft with a pot and beam floor, so obviously the ground is pretty bad for conventional footings.

I have dug an inspection hole down to around 1 metre, its just general soil with stones mixed in etc, no sand or clay etc. Whats the best way to proceed, if I continue to dig a trench down will it cock it up for the piling which will have to be done or can the trench just be back filled and then piled? Its only a small extension, 5Mx3M double story.


Second question is on planning, the PD rights have been relaxed recently and I can now build a 2 story extension 3M out without any planning permission. Except I fall foul of the rear boundary distance, apparently the fence has to be 7M away from the extension, mine is only 6M, however behind the fence is a couple of metres of scrub land, then a lane and then across from that some farm outbuildings/containers etc, its not overlooked at all.

I would rather not go down the planning route if I can help it, I was thinking of moving the fence back into the scrub land or taking it down altogether so there is no boundary. The fence is a bit of an odd shape at the back anyway and I was thinking of straightening it up at some time, would pulling a fast one like this open up a world of hurt with the council? you know how they get if they cant dictate this and that to you whilst wearing a high viz and carrying a clipboard. Or is the 1M discrepancy so minor it makes no difference.

Just to be clear its not the planning fees that I'm trying to avoid, just the weeks of nazi officialdom.

[mickmcpaddy]

blueg33 said:

I would want to know what the ground conditions are. Why a raft and not piles in the first place? (probably cost but not always) I would have though that if the house is on a raft and the extension on piles the risk of differential movement would be quite high.

If you pile it, what design and structural info do you have to tell you how deep the piles should be, what type of pile, what size ground beam etc?

These are the things I need advice on, I have no idea why the house was built on a raft, I am almost certain it is a raft from what the neighbours tell me, when we dug the inspection hole against the side of the house the bricks were sat on a concrete foundation a bit wider than the house but with a very rough side to the concrete, not at all like the side of a concrete footing I have seen before. Also its definitely a pot and beam floor as inside its a screed finish that you can tell is hollow underneath, also there are air vents round the outside.

What would be the best way to add an extension to a house that is built on a raft, maybe if I did a bit deeper then conventional footings would be ok, who knows. Its only a small cul-de-sac I'm on and the house at the other end had an extension and their conventional foundations only went down the minimum, the ground was perfect for building on.