If the rumpus is going to be used as a family day care room, then I think the powder room should be accessible from there. This will make it so much easier for one person to supervise the kids in the room as well as the one who is heading off to the toilet. Perhaps you also need a wet area in there for cleaing up after messy activities. I know someone with a similar family day care set up, and they have toilet and laundry attached to the back of the garage/daycare space. And then the kitchen is adjacent, this makes life a lot easier for the sole person in charge of the kids.

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Hi I have a large bathroom with a closet for washer and dryer. I love it. Off my bedroom. But also have you thought about making study into bedroom with an en-suite and the laundry tucked in there behind doors. If your selling a bedroom downstairs for an older person its very attractive and nice to be separate from the others. Then the two bedrooms upstairs have there own bathroom. Also you are having toilet tucked under staircase for visitors. If you had heaps of space then yes have a separate laundry but it’s a waste of space when you haven’t. I have my laundry essentials in a cupboard under my bathroom vanity which is 1800 cm long and still have two 1m drawers next to cupboard.

Plan c is better using the widest end of the room to locate washer. Size your sink as you may need a 600 deep cabinet for it. Washers, including door which now seem to all protrude 50 mm, come out to 670 once u allow for hose space at back.