It is helpful to start out by thinking about "activities"
rather athan actual "rooms" in determining your space needs.
It may be that several small areas may be better than one large room
for instance; or a separate dining room may be pointless if you never
entertain formally. A bedroom for sleeping only can be quite tiny (
to give added space elsewhere) but if you prefer to study and watch
TV in a bedroom it would be larger than normal with space for a sofa
etc.
Relationships between activities are also important as these determine
the placemetn of rooms (along with sun and views). An open plan relationship
between areas gives a greater illusion of space too so consider what
rooms can be open to each other and what ones should be able to be closed
off; especially kitchen and living areas.
Use this checklist to recall your family activities
and think about what rooms would be most appropriate and what size they
should be.
Sitting and talking with friends (adults and teenagers)
Watching television
Listening to music or practising musical instruments
Family relaxation, together or alone
Doing homework, hobbies or sewing
Playing games
Reading, studying
Preparing meals, washing up
Eating "on the run"
Eating with the family
Eating with friends (dinner parties?)
Ironing
Washing clothes (and drying them)
Sleeping
Bathing etc (including visitors)
Storage on clothes
Storage of linen
Storage of books, toys, records, photo albums, bags etc.
Garaging
Workshop and garden tools
Other special activities (e.g. billiard table)
Of course future resale has some bearing on what
accommodation you build. You have to weigh this possibility with your
own specific needs.