Double storey rear extension

stebiz

Can I ask if a double storey extension is okay these days for planning.

I have a semi detached house. Very little room to the side but a garden that is over 100 feet long. At present I have a single storey extension across the whole of the rear elevation. I am looking at putting another storey along the whole of the rear also. So I won't be adding to the ground used at all but will be to the height.

gavinh1175

http://www.planningportal.gov.uk/permission/

mummyroysof3

Can the existing extension take another story on top?

Furts

You need to investigate the precise construction details of your existing extension - single brick? old cavity wall? timber frame? etc. The wall construction, to meet current regulations, would be different. Indeed it is quite likely not to fit on your existing walls. The existing lintels, if present may need upgrading. Plus the existing foundations may not be suitable. The roof would need tieing in to the existing roof. There is also access, Party Wall Regulations...

In essence, can it be physically built?

On balance, on technical grounds, the answer may be no.

Chopper_Read

Furts wrote: »

You need to investigate the precise construction details of your existing extension - single brick? old cavity wall? timber frame? etc. The wall construction, to meet current regulations, would be different. Indeed it is quite likely not to fit on your existing walls. The existing lintels, if present may need upgrading. Plus the existing foundations may not be suitable. The roof would need tieing in to the existing roof. There is also access, Party Wall Regulations...

In essence, can it be physically built?

On balance, on technical grounds, the answer may be no.

How do you come to that conclusion?

The op hasn't posted any technical details.

Furts

Chopper_Read wrote: »

How do you come to that conclusion?

The op hasn't posted any technical details.

Correct. I said "may be no". It is for OP to establish this.

To move on, it is unlikely that OP extension will be suitable for an extension to give a first floor. Or, it would require significant alteration to accommodate this.

System

on what basis do you make these sweeping statements?!

stebiz

Half of the rear extension (the kitchen part) was built about 7 years ago to 3ft 6' footings, as I was involved in them. The other extension was built during the 1980's and we went past them whilst digging the others. I would say 2 ft 6" in total.

Furts

stebiz wrote: »

Half of the rear extension (the kitchen part) was built about 7 years ago to 3ft 6' footings, as I was involved in them. The other extension was built during the 1980's and we went past them whilst digging the others. I would say 2 ft 6" in total.

If you have brick cavity walls you will be aware the current regulations regarding cavity width and insulation are different to both your existing builds. Basically, the new walls will not align, or bear, on the walls below. This makes it more difficult to extend upwards.

cyclonebri1

Furts wrote: »

If you have brick cavity walls you will be aware the current regulations regarding cavity width and insulation are different to both your existing builds. Basically, the new walls will not align, or bear, on the walls below. This makes it more difficult to extend upwards.

I agree on this 1, the 1st thing after this length of time, that the authorities will want is an excavation to footing level of the existing structure, not difficult in the op's case just a hole dug in 1 or more points. I had to rip up an internal floor and excavate in the living room :eek:for the examination of the spine wall during a loft convertion

Regarding the cavity size, I know the regs now require 100mm to achieve the correct R value with rockwool batts, but can't that be acheived with a higher efficiency insulation in this case?

I ask that as a question as I'm unsure if it will be allowed or not.

Furts

cyclonebri1 wrote: »

I agree on this 1, the 1st thing after this length of time, that the authorities will want is an excavation to footing level of the existing structure, not difficult in the op's case just a hole dug in 1 or more points. I had to rip up an internal floor and excavate in the living room :eek:for the examination of the spine wall during a loft convertion

Regarding the cavity size, I know the regs now require 100mm to achieve the correct R value with rockwool batts, but can't that be acheived with a higher efficiency insulation in this case?

I ask that as a question as I'm unsure if it will be allowed or not.

I was on a site this morning - it got regulations in late 2010. 50mm Celotex with 50mm clear cavity. A site at lunch time was on a more recent approval - 60mm Celotex with 50mm cavity. A site this afternoon has just got approval on 75mm Celotex and 50mm cavity.

This variation represents less than three years. This why I suggested to OP building on the existing extension would, on a balance of probabilities, not be possible. Yes, there are always solutions, but for an extension this is unlikely to be viable.

I accept my view was condemned by a number of fellow mse colleagues - but we are all entitled to our opinions!