oh and by the way, when you walk on it, it seems to be higher at all the seems, but the rest of the board is very secure, and not giving or moving at all, just where all the seems are, you can push the seems down.. So wouldn't that be the expansion of the board bowing, which causes the lift, which in turn makes the board go up and down? But there is more... the actual boards that we still have that are extra, or rather brittle, and those ends I am referring to, can break like super super easy? I do not need to look at the depth of this stuff, as it sounds like form what I have read, if they are too think you cannot put the underlay under them.. However no one ever told us that, and shouldn't the builder's contractor be knowledgeable with this? Seems odd, ugh..

can you take some pictures and post them here?

I'm going to be the bearer of bad news. Most floating vinyl does NOT allow underlay. In fact, many of them will do EXACTLY what you are describing if underlay is used. These planks are flexible and their edges are brittle (as described above). They need RIGID underlay (aka. plywood or concrete) underneath them. Anything "squishy" (like foam underlayment for laminates) is likely to cause the vinyl to bend and the edges to "snap" (hmmmm...sound familiar?).

Somewhere in the installation instructions it will SAY what it can be installed with. Today's installation instructions will CLEARLY LIST the products that are ALLOWED. If it is not listed, it is not allowed. Whomsoever told you "...yah. Underlay is fine," didn't read the installation instructions. As the purchaser/material provider, you would have read the instructions yourself before purchasing the underlayment.

I've researched products for more than 7 years, and yet I am UNABLE to find WRITTEN instructions on the web. That's disturbing to me. It means "Coastal Estates" is a generic name for someone else's vinyl. Find out who MAKES the stuff and you will find the installation instructions on-line. Until then, it will remain a mystery.

As the purchaser, you will be responsible for providing all the materials needed to install the product. If you purchased underlay and handed it to the builder (who does NOT normally install vinyl floors) then you are responsible for the mistake.

In case I am wrong, you should find a BOX of the stuff (you bought it = you own it) and dig out the INSTALLATION INSTRUCTIONS. Read them CAREFULLY. Ask yourself: "Is underlay (the soft stuff) mentioned ANYWHERE in the text?" If it is NOT listed, it is NOT ALLOWED.

And "no" the GC's installer will not "read" anything (which is what needed to be done BEFORE it was handed over to the builder). These guys are not "flooring professionals". They are "guys" who can swing a hammer. You became the "flooring professional" when you purchased the product. And the "guy" who installed it became your "subcontractor" or your employee for that part of the project. In this case, you became the GC for the flooring. And the GC (ahem...that's you) would be responsible for any/all concerns or problems for that section of the project. The subcontractor's work is the GC's responsibility (which you took over when you purchased your own product). The builder would be responsible for all of this is S/HE had PURCHASED/SUPPLIED the vinyl. But s/he didn't. And s/he isn't.

Please list the brand of UNDERLAY you purchased and the thickness. I should be able to say whether or not it is too thick/squishy for vinyl. Does it say it is rated for "vinyl planks"? Most are not. There are VERY FEW underlayments that are SPECIFICALLY rated for vinyl plank products. Very, very, very few. And they are EXPENSIVE. So expensive that most people gasp and then skip that step.

Here's a hint. The underlayments that are "rated" for vinyl are traditionally 1.2mm THICK (about as thick as a "fake finger nail") and are made of "mass loaded vinyl" which can be as much as $1.20/sf. They are often gray (some times a charcoal colour) or a super dark blue (almost black). Does any of that sound like what you purchased?

" I am UNABLE to find WRITTEN instructions on the web. That's disturbing to me. It means "Coastal Estates" is a generic name for someone else's vinyl. Find out who MAKES the stuff and you will find the installation instructions on-line. Until then, it will remain a mystery."

Yup - I did the same thing - looked for the install instructions. Can't even find the product!

"we were specifically told by numerous people we could put the underlay in."

What matters is if the manufacturer of the floor stated it.

Pay a real pro to demo, PREP, and put in real wood flooring. Not cheepchinesecrapola plastic.

Well THAT ^^ was certainly helpful.