To install an external aircon unit on the boundary wall of my property?

[Namechange129010]

We would install it on the exterior of the first floor wall, but our garden is on the other side, It would mean the unit would protrude outside of the property boundary, onto public land, but not be visible by any neighbours and it not a pathway or anything. if this doesn't bother anyone and no one can see it, is it legal?

How exactly is it public land?

I don't think you can legally do it (although I'm not a lawyer). A planning application for a small house on a small plot near me, was turned down because the windows would have opened onto land owned by the local authority.

Check with your local council.

Iits a bit of wasteland then trees then a council run car park.

I think it would need to hang over land that you own.
As pp has said, you can't have windows opening over the boundary.

Thanks all, if it turns out to be technically illegal, we are also wondering if this is a 'better to ask for forgiveness than permission' type scenario.

I believe you need planning permission. And do it the right way (not 'ask for forgiveness').

There is no 'technically' about it. It is illegal.

The question for you is whether you want to take the chance on it being discovered and you being made to take it down etc or not.

Or are you looking for validation that you should/others would?

You would definitely need permission from whoever owns the land, and they may insist on a lease/licence for the use of their air space.

You're a CF if you do that, you've no right.

People who try to take what is not theirs are a menace.

However, if you do go ahead, I hope you're reported and made to remove

That’s not how it works. You need to speak to the planning department of your local council and apply for permission. Just putting it up is risking a lot of money to take the whole thing down again and make good.

We have aircon in 2 upstairs rooms - the units are attached to the wall about 2 feet above the ground with ducting running up the outside wall and then into the upstairs rooms. Could you do this so that the units are on your property? (You could be made to remove the units if they don't meet planning requirements so would end up with both installation and removal costs....)

If its illegal you will be made to take it down. You cannot build on or over other peoples property. If you don't own the land then you cannot do it.

Yes I guess this is what I'm asking....and getting honest answers which is useful.

Another option would be having the aircon unit in our garden...but would mean running pipework round, so there would still be a a few narrow pipe works protruding the boundary wall slightly...would we need permission for that?

What part of 'you can't extend past your own boundary' are you struggling to understand?

No, because if you ever wanted to sell the house it would be a nightmare. Plus permission wouldn’t be given so you’d have to move it, no idea how big a job that would be.

Of course you would. It’s still not your property.

You need planning permission. If the unit is within 1m of the boundary. You could call the planning department and see what they say.

Could you ask about purchasing a slice of the land? It is often older houses where land has been carved up differently over the years that end up with these weird boundaries imo. If it is wasteland they might be open to it?

Cite your sources please

(as someone who has a relatively newish mews house whose boundary ends literally on my front door, with no path - whose windows open outwards )

How about not putting in an utterly unnecessary aircon unit in the first place and just opening the window?

I think your windows would be ok as they are an original part of the house built up to the street. So there is a precedent which predates planning permission

Land Registration Act 2002
If there is an overhang, the following principles can legitimise what would otherwise be a trespass:

The deeds to the house may specifically provide a right for them to be there;
If the overhanging gutters have been in place for over 20 years, then the owner may have acquired a prescriptive right for them to be there. In certain circumstances, use of a neighbour’s land can be acquired by right through long usage. It is possible to acquire a right to drain rainwater through overhanging gutters;
If they have been in place at least 12 years, then it is possible to acquire actual ownership of the airspace that they occupy. The new rules on adverse possession in the Land Registration Act 2002 make this less likely, unless the gutters were in place at least as far back as 1991. However, it is possible to acquire adverse possession of a piece of airspace, even if the ground below has not been possessed;
If the projections have been in place for some time, or are part of a development, then it is arguable that the land bought included the overhang into the neighbouring airspace. This gives rise to a boundary that is different above the ground from on it, but that is in theory possible – and in practice even desirable – to allow gutters to remain.

Why can't the pipes enter the property on the garden side, why do they have to run round the outside?

Is it a loft above the first floor, could they come in and run through the loft to get to where you need them? Or boxed in against the ceiling or something?

@QuintanaRoo

Thank you - you just put my mind at rest! (I got a bit of a worry on)

its not really that feasible for pipes to come in via the garden due to the layout of the house and the rooms where we need the aircon. the internal aircon units will be mounted to the boundary wall as there is nowhere else to put them in those rooms. the external unit, if in the garden would not be attached to the house as it doesn't look great and in the view of neighbours. There is a place in the garden where only we would see/hear it, but its quite a hot area, the side wall is much cooler so the system would be much more effective hence the original idea.