one of the bits i read the other night
" How big can I build a barn without planning permission?
If you’re constructing a barn on your land solely for agricultural use and the land is 0.5 hectares or more, you may be able to build without the need for planning permission.
Permitted Development rules for agricultural buildings like barns also state:
• The barn must not be used as a dwelling
• It cannot be the first agricultural construction on the land
• It cannot be more than 75 metres away from principal farm buildings
• I cannot be less than 75 metres from any neighbouring house
• The maximum floor space permitted is 500 square metres
• The maximum height permitted is 12 metres "
and this was also very interesting ....
" Since 2014, if you wish to convert an existing barn outbuilding into a home in England, you can do so under Permitted Development rules in some cases.
In order to convert your barn with no need for planning permission, the building must:
• Have previously been used solely for agricultural purposes
• Have existed since at least March 2013
• Have a total floor space of no more than 465 square metres
If you want to convert an existing barn but your property lies in a national park, conservation area or Area of Outstanding Natural Beauty, however, you’ll need to obtain planning permission.
Barn conversions are also subject to ‘Prior Notification’.
This means you must notify any boundary neighbours of your plans, so they have the chance to object.
Under Prior Notification, you must also apply to your local authority to establish whether or not you need approval for issues like transport access, noise impact or flood risks. "