House extension adds value (?)

[Deleted User]

Just a rhetorical question.

A 2 bedroom house on a road with no ceiling price has a 2 story extension.  Just bedrooms/ living spaces. No kitchens or bathrooms.

The extension adds 30% to the value of the house. 

How many average size bedroom(s)/ living spaces would you expect this extension to have to add 30% to the value? 

(I know there are so many variables, I'm just wondering what your best guess would be.)

womble12345

For 30% I would want maybe 1 or 2 bedrooms extra

theonlywayisup

All roads/areas have a ceiling price. 

Normally to add value you add a bedroom.  But you need the bedroom to have adequate living space to properly add worth.