Hi szruns. From what I've learned it's almost never wise to disregard the manufacturer's directions regarding your concern. Here's some info on tubs from gardenweb to get you started. A lot of it is still current. http://ths.gardenweb.com/forums/load/bath/msg1201101028412.html I'd suggest you do a search on this site - you'll find lots of other useful info on tubs, including some on the kind of tub you're looking for. I did that kind of research when I was remodeling and found it very helpful

Please pardon me for chiming in, but this subject has recently peaked my interest. Someone has just mentioned about the floor being level, which I think further complicates this subject for the antagonists of using the mortar bed. I believe what they are talking about is the parallelism between the ledger board and the floor, since we can get too hung up with the floor being level. I am the first one to admit, that when you consider something very simple some comes along and says , not so fast, and someone tells you something that is hard to comprehend as to why. I must admit that this whole subject is very new to me, but I think what the people instructing us here are trying to get us to visualize is, imagine the tub sitting flat on the floor with no ledger board, and then if you could somehow put the ledger board in after the tub is already sitting on the floor with just the same pressure pushing up on the board as the pressure of the tub has against the floor , that would be Ideal. I think that is what they are trying to tell you!

I would guess your valve does not have shut offs, so blowing out a hole that large makes no sense. Why have a 5" diameter hole??? You would have a balancing stool, so blow out another inch to the right to expose the slotted piece so it can be removed. As long as you can get the pin and cartridge out, you are good to go. The cartridge is your maintenance issue going forward, if any. If the hole is closed up too much, sometimes you cannot lift the pin out, so make sure the room above the cartridge is adequate. If your valve does have shut offs, just enlarge the hole to expose, but no more. Just make an oval or rectangle to emcompass the parts you need access to. Again, most valves are sold without the shut offs from home centers.

Since it's on you, I'd go after Kohler again. Simply start anew. Get a written diagnosis from the second evaluator. Send it to Kohler and start a warranty claim. Pretend it's the first time you've called them. 1) Tub was purchased from _____ on ____. 2) Tub was installed on ____ by a licensed plumber in accordance with the manufacturers instructions. 3) Within days of the installation a squeaking noise was heard. 4) You had two people come out and diagnose it as a delamination. Include the written report from the second person. 5) State what you want: A new tub. I'd also contact the point-of-purchase. They sold you a bad tub. As a follow up to the initial phone call claim with them, include the written delamination assessment made by the second evaluator. Send them the same info noted above. Written letters and emails start the paper trail. Phone calls are great to "shake the tree", any time you talk to anyone note the day, time, person you spoke with, case/claim number if they assign you one, and take brief notes of the conversation. Kohler is usually pretty good about claims. Best thing I can offer is to be calm but firm in your conversations, be businesslike. And keep good notes. When I've dealt with things like this, I've kept my notes in a document file on my computer. If I talk to someone new, I'll email them the file while I'm on the phone with them. Depending on the situation I might password protect it or convert it into a pdf file before sending it so it can't be muddled with by the recipient. No, I've never done or had done a gel injection. I've never heard of it being done. Not saying it won't work. But I've never had a tub delaminate! As a bit of a last resort, talk to your GC. If Kohler is claiming the tub was installed incorrectly, that falls back on him and on his plumber. You might be able to get separate letters from the plumber and the GC saying that the tub was installed IAW the manufacturers instructions and that they agree with the evaluation that delamination as a result of a manufacturing defect are the cause of the squeak. Again, all that is based on the tub having been installed correctly. ie, it's not a drop-in tub that is being supported by the rim instead of by the base/feet for example. Again, good luck.