Options for rear extension in terraced house no rear access

I guess it is going to be more expensive compared to a semi or detached house.

I spoke to an architectural tech last week who suggested methods involving piles/pads/screws at (I assume) the corners of the 4 x 3 metre single storey extension, with steels or similar between them. Presumably this requires less digging and less removal of soil in what is a cramped and difficult area.

Does anyone have experience of this or any other suggestions? Will I find it difficult to get a builder who has experience of these methods? Will building control be happy? The architect seemed fairly confident he could convince BC!

There's no reason why an extension to the rear of a terrace should be any different to any other extension. The only difference is everything needs to go through the house, which will add a bit to the cost but not as much as expensive engineered foundations that won't save you any digging anyway. Just allow for new carpets at the end of it.

Err yea, that tech sounds like a Loony!

screw piles and poured piles and precast piles can save money on large ground works costs on large scale construction sites, however, you require a piling machine to install the pile... how is that getting into hte back garden?

Also, you still require a trench foundation to attach the piles to each other, so you will still end up with a similar dig anyway.

my builder dug my foundations by hand and installed the concrete using a pump, this was round the side of the house, but this was through a very narrow gap. no mess inside for me, but was all manual labour.

So shouldn't be any different for you, with the exception of going through the house.

Thanks for the replies. To be fair to the architect, he was throwing ideas around. Good point about the cost of engineered foundations versus digging a hole.

He also mentioned that the new CDM regulations come into effect in April, but he was a bit cagey about cost etc. anyone know the cost implications for a very small build like this?

£12-18k