Here, also, he drove screws right into the back panel, and it's caused the left and right ends to bow:

One portion of our island will consist of two cabs, back-to-back:

However, same issue: there is a 1/4 to 3/8" gap between the two back panels, and installer has just sent screws through, resulting in either the panels bowing outward or hollow gaps where the screw threads are just exposed in the void:

Can anyone please tell me if these need to be redone? Or is it perfectly fine and considered just an alternate but acceptable way to install?

Thanks much.

I'm not a pro, but I would definitely shim those spaces. That's what I've always done when I installed my own cabinets. As you've pointed out, without shims the cabinet backs bow, and the screws exert unnecessary pressure.

Thank you, mathteachr. It just seems like common sense to me -- and I can't help but think this sort of warping isn't good for my cabinets.

I combed the internet -- apparently not well enough! How did I skip over Bob Vila?! :) I'll need to get up on a ladder tomorrow and check the wall cabinets. I know in one corner, there was an inexplicable gap where drywall dust had fallen through the top (his asst was sanding joint compound near the ceiling) and collected in the bottom shelf. I wonder if he similarly attached the wall cabs (i.e., no shim between panel and stud), and bowing caused a similar gap at the top of that cab. Ugh!

Get plastic or composite shims as wood will compress over time and potentially loosen up.

I always specify in the final drawings and notes to installer to shim any voids where screws are attached AND not to over-torque the screws. Snug is adequate. A minimum of 1" of screw needs to be in the stud which typically means 1-1/2" into the wall. This is particularly important with inset cabinets but simply best practice with any.

Thanks, mill! You're the second person who's recommended using plastic/composite/non-compression shims over the past few months. I don't know if you noticed in my third photo (left side of cabinet), but the installer used Wilsonart laminate samples/swatches (2x2" pieces one gets from a Wilsonart dealer - hole punched and hanging on a ring) piled together as shims in this one area, but also underneath all of our cabinets (to level). DH and I thought this unorthodox (and in my mind, they qualified as plastic/non-compression); we checked w/ the installer, and he says he 'does it all the time - it's fine'. We had quality concerns with the product, in addition to many drawers being off by 1/16" wide (with 5-piece shaker drawers, one can easily see the misalignment), and the cabinet company's regional rep paid a visit. When I asked him whether the piled-up laminate swatches were ok to use, he said they were "hmmm, interesting...never seen that before", but the should be find and would not void any warranties. (Underneath some of the cabinets, the swatches were sandwiched/piled up 5-6 high.)

Thoughts? We want this done properly and feel within our rights to demand this (esp given the expense of these cabinets), but I don't know where this becomes a homeowner hovering and interfering with the installer. I've read and viewed countless cabinet installation tutorials and how-to's, and all I see are the basic, wooden shims being used.

Shims loosening up: this has already happened with these sample pieces. In areas we can still see (end panel of sink cabinet and dishwasher panel), the originally placed shims appear to have slid away, leaving a small gap where the shim used to be. Very concerning. We'll address this on Thursday, but what about the areas we can't see? They've already attached the toe kick skins and shoe moulding.

Would appreciate any further guidance. We're moving into month 14 (month 5 with the cabinets) of what's been a very difficult reno. Thanks again.

Mark - thanks for your input. My KD has been on-site a few times, and I had to point out all of these issues to her. I don't know what the dynamic is between KD, owner and installer, but communications among them appear (to us) to be a bit muddied (i.e., it's the owner who tells the installer what to do, but it's the KD who knows the details of our kitchen). Installer has an assistant helping out, and I can hear him being overzealous with the impact driver. He's broken a screw at least once (and blamed it on the screw hitting wood....um, come again??), and I've heard the installer chastise him on another occasion.

Similar to these:

I don't see a problem using them but i would probably want to them them held together firmly of possible if going the 5 or 6 high route at they definitely tend to slide around. Even taping them together once around with a clear packing tape possibly.