House extension costs?

Just looking into the possibility of extending our house at the back, as have a large garden doing nothing useful, but in need of a dining area - either by building a brick attachment with roof thing, or having a conservatory. Which one is best?

Has anyone done this for a semi-detached, is it worth the hassle, how long did it take and how much did it cost roughly?

Thanks

There is not a huge differance in cost between the two but a conserv' will work out cheaper. A brick extension requires planning and building permision which requires plans to be drawn up. Expect to pay around £15,000 depending on exactly what you want, a conserv will cost about £10,00 depending on size. Give more details and i will be more accurate.

Hope it helps.

a conservatory could be between 5 and 15k, depending on size and complexity. It cannot be open to the main house though, it must be seperated by an external lockable door.

A brick extension would (these are estimates i've made for myself before) be between 10 - 20 for a single storey and 20 - 40 for a double storey, depending on size etc... And as noted already would require planning permission if above a very small size.

I know someone who is having a garage built on with a bedroom/bathroom above. They have been quoted £32K for just the building work (including wiring/plumbing/plastering I think).

Hi

We had a single storey Kitchen/dining extension added to our house full width of back approx 4'5 metres and 2.5 out! It did not need planning permission or architects drawings because our builder (a family friend) did it under a building notice/building regs only - Check with builder/council first it can be done this way and saves a packet but usually they don't tell you!!!

Obviously every property is differant so save yourself a lot of money by doing good research first!!

Originally posted by Cyclone

a conservatory could be between 5 and 15k, depending on size and complexity. It cannot be open to the main house though, it must be seperated by an external lockable door.

 

A brick extension would (these are estimates i've made for myself before) be between 10 - 20 for a single storey and 20 - 40 for a double storey, depending on size etc... And as noted already would require planning permission if above a very small size.

Obviously depends on size, type etc. but these are realistic figures for an 'average' conservatory or extension

A conservatory and an extension are both covered by the same rules under 'permitted development rights'. This limits the size of an extension/conservatory you can have before planning permission is required. It's calculated on the increase in volume, but I don't know the threshold figure off the top of my head.

To clarify cyclone's point - IF a conservatory is open into the rest of the house it will need to conform to the new regs for heat emmission that applies to all new windows. If you can prove it is thermally isolated from the rest of the house you can have it made of the cheaper heat-leaking glass.

And buy a couple of copies of the 'homebuilding and renovating' magazine for loads of useful advice (or look a relevant edition up in your library)

I thought all conservatories were excluded from the planning permission if under a certain fixed size. Whereas an extension (or conservatory open to the main house) needs planning permission if above something like 7% of the floor space of the house when it was built.

Conservatories are exempt from planning permission in most cases but you must inform the council that you are doing one and they will tell you if planning or building regs are required in your case. To get away with no planning permission the conservatory must not be open to the main house as mentioned before, not have a permanent source of heating, not have a toilet and not be used to sleep in (so no nodding off on a Sunday afternoon).

The main thing that you have to worry about is the Party Wall Act which is being enforced more theese days and if you don't follow the proper procedures then your neighbour can make you stop work and there is nothing you can do.

Building notices are ok if the structure is straight forward however building control officers are not keen on then because they have to decide if things are ok, so you need builder that you can trust to do the job properly in the first place.

But you still have to apply to planning and if they say they want plans (which they will) you have to provide them which is why builders use building notices for work that doesn't need planning consent.

Hope that helps a bit.

Originally posted by Cyclone

I thought all conservatories were excluded from the planning permission if under a certain fixed size. Whereas an extension (or conservatory open to the main house) needs planning permission if above something like 7% of the floor space of the house when it was built.

Not floorspace - volume.

Here we go: (dug out the assignment on it from last year)

Planning Permission Not Required For:

*A loft conversion

*The insertion of roof lights

*A roof extension up to 50m3

*An extension of up to 15% of the original volume of the property or

70m3 (including a roof extension)

*A 2 storey extension

- <15% original volume

- roof height no greater than original

- if within 2m of boundary not to exceed 4m high

* A single storey extension with pitched roof of height not exceeding 4m to ridge (and conforming to above points)

Source: Homebuilding and renovating mag

So why do you need permission on a porch if over 2.99m2?

Because it exceeds the building line and may cause an obstruction to your local neighbourhood watch members or somebody driving down the street???