"Each house is white."
Translation:Elk huisje is wit.
Normally house will be huis, only if you want to put some emphasis on the smallness or cuteness of the house it's changed to huisje.
There are some specific words for which is it normal to use diminutives, e.g. meisje or things like een lekker bakje koffie (a nice cup of coffee). Apart from that kind of usage or specific emphasis I would say be sparse with diminutives, because you will sound like you're talking to a baby or very small child.