Maximum garden room size no longer 15sqM?

[dance621]

I am wanting to build a 40sqM workshop in my garden. The garden is large so the 50% rule doesn't apply. I seemed to remember a maximum 15sqM without planning. But the planning portal doesnt mention that limit at all. 

 

I have seem a few websites reference it. Can someone please confirm? Did the rules change?

 

Thanks

[Nickfromwales]

https://www.planningportal.co.uk/permission/common-projects/outbuildings/planning-permission

 

 

• "No more than half the area of land around the "original house"* would be covered by additions or other buildings."