An animal in a compact house is mostly a storage and a floor-finish question, plus one thing people never think about until it happens: what the house does when you leave.
Floors take the punishment
Claws mark soft finishes and wet paws find every unsealed joint. A resilient floor with welded or sealed seams handles both; an oiled softwood does not. This is the finish decision worth spending on.
Keep a hard-wearing zone by the door with a mat well or a recessed tray. In a small plan the entrance is also the living room, so the dirt has nowhere to be contained unless you plan for it.
Feeding and sleeping need a designed place
Bowls in the middle of a compact floor are an obstacle. A recess in the kitchen kick space, or a shallow niche under the stair, takes them out of the route without taking floor area.
The same for the bed. An animal bed in the wrong place blocks the one clear path through the house; in the right place it fills a corner that was doing nothing.
Storage for the animal is real volume
Food, leads, towels, toys, litter, a carrier and the vet paperwork add up to a shelf and a half. It is not much and it is exactly the volume that gets forgotten when the storage schedule is written.
A cat litter tray needs a ventilated position out of the living space. In a compact plan the usual answer is the bathroom, which means the bathroom needs the room for it.
Leaving the house is the thing nobody plans
A well-sealed compact building with the ventilation running is comfortable when you are out. Without ventilation, on a summer day, it is not — and unlike a large house it heats up in an hour, not an afternoon.
Specify a summer bypass on the ventilation and external shading on the main glazing. Those two together are what make the house safe to leave an animal in.
Outdoor access and the terrace
A cat flap through an insulated wall is a detail, not a hole — it needs a sealed, insulated liner or it becomes a cold bridge and a draught. Ask for it before production.
A fenced or screened section of terrace does more for a dog than any interior arrangement, and it is the same screening that gives you privacy.