You can use spare room as a store room. If you have a basement that is a great place to stack away extra stuff.

It is difficult to have a special place for storage requirements as houses today are very compact. I have used the space underneath the staircase for this purpose. I have also constructed a shelf almost near the kitchen roof for stacking away the kitchen items which are not used frequently.

Do you need a store room for the kitchen or for all purpose? For the kitchen you can create extra shelves and mobile counter tops with storage underneath. For other things you can have a shed built in the backyard or a space in your basement.