I put in another post, but back to this one because it has all our job details. We were going to try to rip out the subfloor today and put in 3/4"T&G that my husband bought yesterday. After peeling back some adjacent carpeting and remeasuring, we decided that the base subfloor is actually 1/2" as someone initially suggested that surely it was. That is better, but the particleboard is going! I was trying to get a reply whether we should take it down to the joists or now leave the 1/2" and top it off with the 3/4". Also, not sure about what to use to seal off the particleboard that must be left at the perimeter joists. Silicone or poly or what? Then, I have gotten this other idea which am not sure which is best. Was thinking that cement backer board comes in 1/2" and now wondering if it would be logical to just use the plywood and top it with 1/2" cement backer board. Would that be an adequate subfloor or should we top the base with another layer of plywood first? If so, better another 1/2" or the 3/4" which is going to raise the floor a bit by the time we are all done? Thanks!

I'm not a pro, but I've been doing a lot of research about this exact issue in the last month, in preparation for a DIY project. (I was a professional woodworker before retiring, just not a flooring person). I just want to reiterate one thing about Luaun and to suggest what I think is the reason for the failure. First, luaun is plywood, and, yes, it is commonly used, but it's a poor choice. It's smooth, but has many voids, which can compress after the vinyl is installed, with results similar to what you already have. Do not let them use luaun. The birch plywood mentioned above is good. Multiply is one brand name that is carried by my local Home Depot. It's 5mm thick. As for what happened, I don't think what you are seeing is the underlayment having moved or buckled. Rather, I think they simply layed the vinyl over an uneven underlayment. Sometimes it can take a while for the vinyl to "sink" into the gaps, so you start out with a floor that looks fine. But as the months go by, things begin to get uglier. The only reason I point this out is to suggest that you be skeptical of any claims they might make about your house settling or "unknowns" or whatever. Now, if you had walls built below this floor or something in the meantime...and they pounded them in, it's possible this could lift a few joists, causing something like this, but, setting that aside, your 30 year old house probably did most of it's major settling a few years back. Essentially, I mean to say that they did it wrong, period. There aren't any "unknowns" here that they can summon up to garner your sympathy. As for the appropriateness of installing Multi-ply (not luaun) directly over your existing vinyl, I'm not qualified to judge. My suggestion would be to call another flooring expert in to have a look. Tell him/her in advance the reason for the visit and offer to pay for an hour of time. The frustrating part about this stuff is that, even if the folks who installed this are willing to work with you, they may not be qualified to fix their own work. I wish you well.

Wood subfloors require expansion joints. I have subfloor panels with instructions printed on the boards to leave a 1/8 inch expansion joint. Yet, the idiot contractor butted all joints together. Now I have squeaks and high spots where the floor pops when someone walks over it. The reason for an expansion joint is obvious. Wood expands and contracts relative to the humidity surrounding it. Also, wood floor manufacturers will tell you the same thing for subfloor preparation.

Yikes jn! Right now we are looking at what other options we might have to cover the mess up like a thin coffered ceiling in the kitchen and perhaps some faux beams in the cathedral. Did your ceiling seams get corrected? The wood guys are starting installation today. They will cover the floors with paper when they are completed. Our cabinets are being delivered today as well. All the doors and trim work was delivered last week, we made the poor guy haul it all back out the garage when he stacked it in the great room because we didn't want it the thin coat of drywall and paint to get on it. I just keep telling myself to take deep breaths, deep breaths!