You absolutely want a plywood sink base. No if, ands, or buts about it.
I am somewhat concerned about the formaldahye in particle board and the the health problems associated with it.
My cabinets were made with particle board and my baby has allergies and none of my other 7 ever had allergies. I may just be paranoid, but If I had to do it over again I would go with something that doesn't come with a formaldahyde warning.

M-S M-2 and M-3 are all standard grades for cabinets so with M-3 you are getting the best. Youd didn't provide a thickness (I assume 5\8 or 3\4). Pretty much all the exposed particle board is covered with melamine so not a lot of opportunity for off-gassing. It probably will come down to the melamine - some don't like it others do. I think it is practical and I don't get any thrill from looking at poly'd ply (thin layers or particles it still isn't wood and I don't need\want an aesthetic experience opening my cupboards). With current hinges popping them off of the carcasses and clipping them to new ones is not a big deal - they are meant to come off you don't even need tools. Sink base? No loads of folks with PB bases who don't have any problems but I suppose you never know - water will penetrate a poly finish faster than melamine and who knows how resistant the ply will be to de-lamination (does foreign made ply have to meet ANSI standards?) To me its not a big deal but I'm sure some folks can provide some anecdotal experiences to justify doing the sink base in ply. Ultimately it is about your comfort and satisfaction.

OSB is good.
http://en.wikipedia.org/wiki/Oriented_strand_board
it's dimensionally stable.

it turns out good for you.

wow... this happened to vitamins, too. she ultimately waited for the plywood cabs to be reordered. but her kd was giving her a bit of a hassle.

in your case, i'm a little concerned that the plywood comes from china, even though it's CARB certified. i'm sorry to be paranoid, but the business practices over there aren't exactly stellar.

i think the MDF is only in Phase 1 of CARB compliance, so there might be some degree of formaldehyde in it still. (unless the company has already voluntarily gone to Phase 2, which has even less.)

from what i've read, some people are more comfortable getting a plywood sinkbase. but with any major water damage, i'm not sure if it will help or not.

but yes, you need to decide what YOU really want. you did originally specify plywood, and it depends if you are okay with melamine interiors, too.

there are other threads about plywood vs. particle board if you google them. here's one, but it's from 2008 before CARB went into effect: Plywood or Particle Board me, i ordered all plywood anyway. good luck. :)

Here is a link that might be useful: Vitamins' Particle Board Delivered Instead of Plywood Thread

re: "If I keep the cabinets as they are with the particle board should I have the KD replace the sinkbase and toe kicks with the plywood product."

Personally I'd probably stand firm and get what I originally asked for, but if you go the above route I would do both those things and I would also have her replace any cabinets that have exposed ends with plywood sided cabinets. Also cabinets that have interiors showing (e.g. glass door cabinets). Personally I don't mind having the melamine interiors that are hidden when the doors are closed, but I really did not want the melamine finish in my face when I'm working/standing/walking through the kitchen. Using plywood trim pieces and on exposed sides you should get the look you were originally going for. IMO she should kick in those fixes for free.

I don't know enough to comment on the pros and cons of particle board vs. plywood, but if you accept the particle board, I would certainly expect more than the refund of the plywood upcharge in return! You would be doing the KD a huge favor and it was his/her mistake, not yours. The sinkbase and toekick replacements would certainly be a reasonable request--or whatever else would make you comfortable with accepting something "less" than what you originally wanted.

I'm not a KD but I doubt requests for finished interiors on open cabs or exposed ends would be affected by the change from ply to particleboard. Not sure I would want exposed ply in those spots anymore than I would want melamine but that might just be me.

There should be no problem swapping the doors if you decide to do that. They just click on and off the hinge bases and the cases will be standard dimensions, I'm sure...

What CARB level are these certified? You can definitely get either MDF/particle board or plywood that are certified CARB phase 2 (newest and strictest), with extremely low emissions rates. "Regular" particle board indeed off-gasses badly, but so does "regular" plywood. It's interesting that the formaldehyde emissions are listed for the ply and not the particle board. The CARB 2 levels allowable levels for formaldehyde emissions are 0.11ppm (mdf), 0.09 (particle board) and 0.05 (ply). I don't know how ppm translates to the stated mg/L in your specs :( I linked a little info sheet on CARB rating below...

I personally chose low-emissions particle board for my frameless cabinets, so I don't think that in itself is a big problem, however I TOTALLY agree that if you decide to keep them, you don't get "just" the refund of the difference. This is NOT what you ordered, your KD made a mistake, and you should expect a more significant discount!!!

Here is a link that might be useful: CARB ratings explanation

Yuck... I personally think melamine interiors look cheap. I'd never keep particle board either (having removed them from the house I know how badly they fail). Yuck yuck yuck. Get what you asked and paid for and remind the kd that this needs to be an expedited order due to their error. (and I'd expect compensation if that delay costs anything).

I have both in my kitchen - 9 years of rugged use and everything is as good as the day they were installed. We are building soon and I told the KD I prefer melamine interiors because it is so much easier to SEE inside the cabinets. I am very far-sighted and have trouble seeing in the dark all-wood cabinets.

Never clear on why poly'd plywood is a mark of good taste but should you be susceptible to that argument check out any mid to to high end European cabinetry (say ALNO or Siematic) it is hardly dripping with the luxurious look of exposed plywood (inside or out). Face frame cabinetry using 1\4 inch particle board sides has nothing to do with durability of frameless cabinetry made with 5\8 to 3\4 inch PB. I have 80's cheap (but custom) 1\2 inch frameless particle board cabinets that haven't failed yet (all on the wall, now the cheapo stapled drawers are a different story). Don't be swayed by deliberately provocative opinions (mine or others) get what you are going to be happy with - should something go wrong you don't want to be second guessing yourself down the line.

John,

I had this same problem when my cabinets were first delivered. I happen to get bad headaches from things made from particle board or MDF. Perhaps that won't happen now that Phase 2 is in effect in California, but my cabinets were manufactured in December so were only Phase 1 compliant. And Phase 1 was not really that strict of a standard. I had specified several times with the KD that the boxes were to be plywood (which has never bothered me), and the contract said plywood boxes but the KD forgot to mark a box saying so in the order. I was offered various incentives to accept them as originally delivered and they had even started installation, but I finally said I wanted what was originally ordered. Money isn't nearly as important as my health and that of those around me!!

Sure reordering delayed the process somewhat (a little over 2 weeks), but I am glad I stood firm. Good luck in resolving your problem. If you want and ordered plywood, that is what you should have. I do not, however, know how to evaluate the options you were given.

Lol Cary...she asked an opinion and I gave one. The poor soul ordered what she ordered for a reason so mark me provocative when I say she should get what she wanted :). When you accept the errors of others you lower you pr standards andalways wish you hadn't in the end.

Many think my stained dark interiors look bad or are difficult to see into. I think plastic looks awful in cabinets,...it's an opinion my dear. As was asked for.

I think you will have fine functional cabs either way. I'd expect the upcharge gone and if you want a different sink cab and toekicks, there should be no upcharge for them.

In an perfect world, every element would be made to the highest possible standard and there'd be no extra costs involved. In this world, we balance cost, budget and wants vs needs. If you are ok with it, I am sure it will be fine. If it would bug you every day, then get it done how you originally planned. Only you know what is a priority to you.
btw - by the time you get further into your project, you may have other uses for the difference in cost.

I would like to thank everyone who commented on the problem. The cabinets are 5/8". I am most concerned about the following:
(1) If I choose to have the carcasses remanufactured in plywood I worry that the doors may not fit exactly right. These are frameless cabinets and the tolerances are very tight. When you look at them all you see is doors. How the doors hang is critical to the asthetics of the cabinets. If the cabinets were framed cabinets how the doors hang would not be as critical.

(2) In frameless cabinets particle board and mdf seem to be the standard because of the stability of these materials over plywood. In frameless cabinets it is important to maintain the squareness of the cabinet. Without a face frame the frameless cabinets must use materials that do not change shape with changes in humidity and temperature. The KD is teling me that I already have the best material(industrial grade particle board) for the type of cabinet that I have chosen. Any comments?

(3)If I take the particle board carcasses I worry about it's moisture resistence and endurence over time. Can anyone comment on the quality of this particle board based on the specifications I listed? From reading posts on the internet I understand there is good and bad particle board. Is this a good one?

Thanks for all of your comments.

I have no opinion on the topic, but just wanted to add that the undercab at sink can be mightily improved by putting coats of polyurethane or such on the interior. In photo below, there is oak plywood on sides and birch-faced stuff on bottom.

We had a leak in our area below sink just after installation. Because so much junk was stuffed in there to get it out of the way, it was a couple weeks before I got around to investigating it. If this niche had earlier been the place where we had used up the last of our flooring finish before cleaning the brush, etc. each usage, I would have a better cab here now. (Torn paper rings are being used here to detect whether there is still water running along pipes. High tech detector system.) Photo taken after days and days of dry-out. We are lucky that there was minimal damage to DW niche adjacent to this cab.

John1950
1) yes. door hang good now
2) yes. best material (industrial grade particle board) for the type of cabinet i.e. frameless
3) i don't know (based on specs posted) but it HAS to be kitchen good or better just to make it this far.

florantha posted an image that highlights a problem for everyone's wood-based boxes. My solution was to remove the base of the box. No "floor". Since my boxes have drawers, the lowest drawer is an inch deeper than it could have been otherwise. I stabilized the box squareness otherwise.

john1950...

just want to reiterate the others: if you decide to accept the particle board, do NOT simply accept the refund of the plywood upcharge.

you should be given a discount IN ADDITION to the refund of the plywood upcharge for accepting a mistake/what you did not order.

Addendum to photo above: cab maker saw this water damage and said, "If this had been particleboard, we'd be making a new sink cab right now."

The sides are oak plywood, bottom is birch plywood. Bottom of the cab had been covered by a pile of soggy newspapers &c. but the edge seems to have been the place where the water pooled and soaked in.

I've had both plywood and MDF, and never a problem with either when it comes to water.

However, I agree with ironcook about getting wood from China. I wouldn't let it in my house. Regardless of what they claim it is, you never know what might be in it.

My first reaction was that Wow, the KD is offering to refund the extra you paid for the plywood because you are not getting the plywood.
Well, of course they would HAVE to refund this. They didn't pay it so why should you.
However, if you were to be so gracious as to say ok, I will accept this mistake of yours, there should be some GENEROUS compensation for that.

regarding whether to accept it or not only yopu can make the decision but it looks like you have been offered excellent advice so your decision can be informed.
Good luck with whatever you choose

igloo,

Yuck isn't an opinion it's a judgment. Opinions generally come with explanations (if they are intended to be constructive or useful). No hard feelings.

While not my thing I get the aesthetic preference for ply. Some manufacturers color match the melamine, though that, depending on the colour may subvert the brightness effect. To each his own.

OP

Suppose it depends on the manufacturer but I doubt they couldn't remake the boxes and give you as perfect a fit. My Mom had a door replacement or two and the new ones fit just like the originals. We mostly see frameless in Canada and the manufacturers have pretty sophisticated machinery.

My conclusion based on my research is your KD is telling you the truth. PB is better for frameless construction than ply (because of the dimensional stability and because of the uniformity of the surface for the adherence of the covering). Certainly the grade of PB is the highest you would associate with cabinetry.

Not sure the linked doc will help but take a look.

Here is a link that might be useful: properties of composite panels doc

What was the outcome? FWIW, I agree with Caryscott...for frameless...definitely I would NOT want plywood boxes!