Is there a limit to how much you can extend a property?

[Karbea]

I live in a 3 bed detached house, part of the reason we purchased it was because there are a couple of ways we could extend it.
I was talking to my gardener yesterday who has worked on the house for years and I was asking him about the history of an internal wall (it's a bit odd), and he went on to tell me that it used to be a small bungalow, that previous people had raised the roof so that we could have an upstairs and extended along the side of the property.
When I told my husband he said that maybe we wouldn't be able to do what we want to do in the future because it might have reached the allowable amount a place can be extended - i've nver heard of this before and have been googling and all I can see is reference to allowable amounts without planning permission.
Does anyone know if this is the case and what the allowable amount is, and how I would find out what the original size was, and is this foot print of usable space (i.e does it matter that they extended up if you see what I mean??)

Sorry a lot of questions...

yes it's 50% of the original dwelling. I'm not sure about the extension upwards - where we live, the issue seems to be with the width of the property. When we extended, the front of the house increased by 50% but having said that, the extension is deeper at the back.

Phone your planning department?

I wonder if they actually adhere to this rule, a house near me has almost tripled its size (was bungalow, now a massive house) and this sort of 'extension' is really common around here.

the limited extension rules are "permitted dvelopment", going over that you need planning permission and then it comes down to the views of the planners, the character of the house/area and things like that. I don't know of any 50% limit, our house is over 100% extended as well.

What you're talking about is permitted development. It has all sorts of conditions about heights, distances to boundary walls etc.

You can extend further but you have to go through the full planning permission process.

Ok cool, thansk ladies. I'm thinking over the garage and on top of a flat roof. So wouldn't be increasing the width, only really the height. It's all speculative as we can't actually afford to do this yet!

Yes the percentage thing only limits the amount you can do without planning permission, if you go to the hassle of getting pp you can do what you like - and also I think there may be a time limit thing, so if a tiny cottage is built in 1700 and extended into a mansion in 1850 then you'd be judged off the 1850 footprint not the 1700 one (I think the cutoff is WWII but please don't quote me).

Ours was initially built in the 70s, but everyone seems to have added bits to it :S

It may also be more expensive than you think - the foundations under the garage are unlikely to be adequate to support a further storey plus roof weight.

Oh I know the garage would need to come down, we'd have to excavate a bit too as we are on a slope, it will be expensive... which is why the question is sort of theoretical...one day, one day..

karbea
Don't wait too long. Planners are much more amenable during times of recession!
Even they are keen to keep the economy going.!

I think there is a limit relative to the size of the plot iirc. We were allowed to extend ours by more than even our architect thought we would get away with as we own a totally pointless strip of land alongside our shared driveway with an even more useless patch of grass at the top of it, so the land sq footage counted in our favour if that makes sense.

There's no hard and fast rule, it depends on your plot and the character of the area and nearby neighbours etc. However, you do need to get planning permission once you go over a certain size.

However, there is an exception - in the Green Belt, extensions are likely to be restricted in size so that you do not adversely affect the 'openness' of the Green Belt. Even if you're in a forest