Here is a key to successful laminate flooring : use only material that is at least 10 mm, not including any underlay. Avoid 7 and 8 mm products entirely. 12 mm ( not including any attached underlay) is even better, but 10 mm not including underlay us minimum! It’s andy better to find narrower planks , less than 5” . Narrow thick planks are not nearly as prone to cupping, which occurs in cheap laminate. More on reddit.com

Additional underlayment is not generally approved under attached backing floors. Generally cause too much deflection. Was the floor flat within the manufacturer specs (1/8” in 6’ circle)? And was ample expansion left around all fixed objects? If you call the manufacturer for a warranty claim and they find any spot that isn’t flat to that spec your warranty is voided. The flatness spec is nearly unattainable in most situations, even by professionals. It’s very rare for a manufacturer of flooring to do a warranty claim they almost always can find something in the installations instructions to get them out of claims. More on reddit.com

Look at the manufacturers installation instructions and read the warranty. You may void the warranty or cause the laminate to wear improperly if it’s not installed correctly, including over an acceptable pad. More on reddit.com

Just so you’re aware, the asterisk on the price means that Costco is discontinuing carrying that product and won’t be available so get all you need and a little extra in one shop, cause if you end up needing more you’ll have to hope someone else has it. More on reddit.com