Are there adjacent cabinets? If so just skip the back.

In twenty five years of owning houses I’ve never had to access the plumbing behind a sink and I’ve always installed cabinets with backs including ikea.

Complete overthink. The backing on frameless cabinets is what keeps them square and true. They are flimsy and prone to racking without it.

Thank you. I am prone to overthink - engineer.

Other potential overthinking: (1) I was also thinking about adding the Fixa countertop support brackets on cabinet sides. It will be 3 cm quartz. Seems like a little extra support between the front and back cabinet brackets, that stand proud and would take all of the support, might be a good idea, (2) 1/2 or 3/4 painted plywood on either side of dishwasher (with painted to match solid hard wood filler to look good) as a protection against steam/water damage, as opposed to cover panels adjacent to the DW, (3) adding additional cover panels to the sides of the 36" frig cab to make the opening 37" (most 36" frig only allow for 1/8 to 1/4" or so on either side - tight fit - and some call for breathing room requiring a larger than 36" cab, (4) remove tile (over slab) where end cover panels meet the floor and then tile up to the panel (maybe a bad idea).

The cabinets are only flimsy and prone to racking before they are installed. Once installed as part of a cabinet system the back does virtually nothing.

However, if you are worried about it, just cut them down to corner braces (all the racking strength is in the corners anyway).

The sink is located adjacent to the DW, so there is no cabinet on that side (as part of a system) to ensure that it is square. Also, the assumption that all of the support against shear is in the corners, I believe, is not quite accurate (e.g., consider the crossbar support on an oven cabinet). A larger panel will likely provide more support.

If you’re really concerned about it, make wood corner braces for the back.

Or metal.

Using only nailers or corner braces is quite common and my shop cabinets don’t have full backs… just nailers and corner braces. The older oven cabinets used nailers that were only attached to the sides… The new cross braces were a cost savings measure.

Unless this is an island it will be part of a system once it is installed. It doesn’t matter that there is no cabinet beside it… you are attaching it to the wall. Use a nailer/spreader on the top like they did on Akurum cabinets and it will be fine. Or not, and just use the back.

The wall ends an only about 10" is on a wall.

FYI: I was told yesterday at Ikea that without the Fixa brackets, the warrantee is void. I am assuming that that warranty issue is on the countertop, because that is what the brackets are intended for. Many installers are not using the brackets. Maybe the Ikea countertop installers put them on - but the cabinet guys don't call for them.

Just cut a hole