Can anyone recommend an online site or local (Home Depot etc) place to source a single upper utility cabinet to put over a W/D? Bit of an odd size as its very deep -
I highly doubt you’ll find a stock cabinet that size.
Building a paint grade utility cabinet out of plywood isn’t that hard.
I built one over our washer and dryer using MDF with sliding doors.
You don’t even have to finish the back or sides.
What woodworking tools do you have access to?
If the cabinet is wall to wall you won't get it through the door opening anyway!
A stock size cabinet will be 24x24x12 deep. Get that size cabinet and trim out the sides to fit the space. Pulling it forward to match the stacked washer/dryer.
no local cabinet shops or carpentry shops around? that's an easy build. are you sure you want to go 31" deep? that's very deep. maybe you could add some sliding pullouts to make it easier to get to the back