If there is anything on that wall which sticks out such as a capping on the vents or suchlike, then that is trespass and you can get it removed. It is not trespass if it is just a hole in the wall with nothing coming out.
The fact that there may be vents coming out of this wall is not relevant.
What can be relevant is whatever comes out of the vents for 2 reasons.
If there is a draft coming through the vents or noxious fumes, then you have a claim against each of the property owners or the developer in common law nuisance.
There is another potential cause of action which is not quite so good and which you would bring in conjunction with the nuisance claim and that is that they are currently discharging air over your property and they do not have an easement to do so and hence, you may have a potential cause of action in trespass because of that discharge. It’s not a particularly good cause of action and it’s not worth bringing on its own, would be worth tagging it onto a nuisance claim.
It seems unlikely that the developer is going to change 10 bathroom ventilation arrangements without some kind of opposition or fight and hence, if a solicitors letter warning him of the threat of court action doesn’t work, then you are faced with taking him to court for an injunction. A word of warning here and that is that if any injunction proceedings are not successful, you could potentially face legal costs running into several thousand pounds. Hence, although a solicitors letter be cheap enough, you need to think very carefully before rushing off to court because if the judge doesn’t grant you the injunctions to get these vents moved, you could easily face legal costs for the developer which could run into tens of thousands of pounds.
Can I clarify anything for you?
Please rate the service positive. It’s an important part of the process by which experts get paid.
We can still exchange emails.