Permitted development extension

[PPPpickUPaPenguin]

I am considering purchasing a property. To work for us, we need to extend.

I understand under PD, you can only go up 4m from ground level. The ground is not level. The difference is no more than 1m, so we should be ok.

I was wondering what extra work is required on the foundations? It would be around 4.5m x 3m. We would be making the extension a kitchen and using the existing kitchen as a dining area with a small utility squeezed in so we can leave the boiler in place the dining area. I am guessing we can use the lintel of the window and make that a doorway into the extension so no RSJ?

What kind of price are we looking at per SM for this single story extension? What kind of time scale are we looking at? We would need the two rooms to be tiled and decorated, including plastering of the dining area after tiles and existing units are removed. We would require services to be moved around, so I guess that would require extra cost.

Not sure what you mean by extra work on foundations if you plan to extend? A single storey extension will need its own foundations capable of supporting it - a structural engineer will be able to tell you what scale and type.

Yes you can use an existing lintel if the doorway is the same width as the existing window.

Typical ballpark figures I give clients for single storey extensions are £1500/sqm. Obviously this can go up massively depending on specification and finish. Allow about three months to be on the safe side but this depends again on weather when doing the envelope and your builder!

What services need to be moved? Relocating sewers etc is a whole different ball game to connecting a few kitchen appliances somewhere else..

That is really helpful, thank you.

The ground level is sloping away from the property towards the rear of the property. The extension is to the side of the property, in the rear half.

Services to be moved into the extension would be gas, electrics and water.

The same services would be required to move a short distance in the existing kitchen to accommodate a washer/dryer/boiler utility cupboard space.

Just bringing services through from the existing house shouldn't cost too much. You will need to factor in a bit extra for the drop in ground level but again it doesn't sound like you'll need significant retaining walls etc