Best talk to your planning department, but generally you don't need permission if :----
It is to be sited in the garden of a detached or semi detached property.
The property is not in an area of conservation or outstanding natural beauty or similar category.
The property is not a listed building.
The cabin will not be between the house and a highway (or if it is there shall be a 20m distance from the highway).
The cabin will not be above 4m in height.
Total area covered by buildings will not exceed half of the garden.
The cabin is not to be used commercially (home office is usually acceptable if it does not detract from the main use of the property).
The cabin is not to be used as a dwelling.
There are no other covenants that prevent you from exercising your permitted developments rights.
I think that under 30 sq. mtrs. you don't need building regs.
If you're looking to buy one I'd recommend that you avoid Dunster House like the plague. They're fine at taking your money, but don't want to know about you if you have problems.
------------- Two drifters off to see the world.
I'm tired of reality, so I'm off to look for a good fantasy.
ID double check i remember a recent article in the paper over a house owner being told to remove theirs Tree house
i know its different but cant quite find the original story i am thinking off.
was defiantly told to remove it because of a distraction to road users or something
so id probably check with planning department and any housing associations.
to be brutal i think its a disgrace the crap you have to go to, if you want to add anything to your house or garden.
------------- if there is magic on this planet, it is contained in water
Planning regs. can be very different, depending on where you live. Its always best to approach your local Planning Office first to get advice. Builders/suppliers of these things will often tell you that you don't need permission but the onus is you. For the price of a phone call or a visit in person, it's worth it for the peace of mind.