Blade (#16)
Sounds like you are going to be lucky, I hope that you have read thro the attached link:-
http://www.planningportal.gov.uk/eng...655490418.html
(Use this or get professional advice only, do not rely on builders or 'self build etc websires)..
Note the 4 m height limit is for the external ridge of the roof....so clearance issues may be interesting...if the R44 height is 3.3m.. plus a trolley etc, say 3.6m;-dependent on the means used, such as wheels and so forth...
Allow say 300mm for structure and roof covering....leaving 100mm clearance...tight to say the least....and the trolley dim might be wrong.
Also check how close you are going to be to any residential building on site.. closer in any part than 5m and it will be considered an extension..and volume limits come into play....check thro that part is it 'polices' up many of the issues which may be relevant.
Just a quick guide....for a R44 with a bit of space around it...so you can walk in and around but nothing special, external dims would be in the order of 13m long, 3.5m wide...area 45.5sqm...if you have 3m tall side walls with a 4m ridge line the volume is going to be around 160 cubic m. You will need Building regs approval however, regardless of planning.
Also as the use (hanagarage for a helicopter) is not necessarily 'domestic' then 'should' somebody ask what it is for then a good 'answer' will be needed, depending on the area in which you live..
Also remember the onus is on you to ensure you do or do not need Planning to erect this building...if you do so and the local Planners deciede that you should have had planning its either a retrospective application or the courts...neither of which are necessarily inepxensive..even to a helo owner.
Keep us posted.