wingrovebuyer : Hello. If you build on land you don't own, you risk being ordered to demolish the building. Accordingly, it isn't a good idea. You will need to buy the extra land so that you can build, or take a very long lease of it. That second option is a bit messy, because then you'd have one building part on freehold, part leasehold and that's not ideal if you ever want to sell. Best option is to buy the land you need. You will need to contact the Crown Estate Commissioners to ask if they'd be willing to sell.
Customer: Wouldn't building on the land give me the same option to claim it after a number of years as putting up a fence would?
Customer: I know the best option would be to buy but I have been unable to find any info about how likely it is that I could do this. I wondered whether this was a common and/or easy/quick thing to do.
wingrovebuyer : It depends. If the land is registered at Land Registry, you could claim ownership after 10 years, but only with the registered owners permission. If it isn't registered at Land Registry, you don't need their permission but the period is 12 years. However, you say the land is crown land. If it is owned by the crown, these periods are extended to 30 years. The problem is, though, that at any time before these periods, the owner could take legal action against you for trespass. Although unlikely, the courts could feasibly order you to demolish the extension. At best, XXXXX XXXXX you pay damages to the owner. You probably won't be able to sell or mortgage the property either, due to part of it not being on your land. Sorry - there's no easy answer. In my view you need to buy the land or just build on your own land to avoid what could be very serious problems.