lvp underlayment voiding my warranty -- risk it or nah?

got a job installing lvp in a kitchen remodel, client picked this coretec brand that claims built-in underlayment for moisture protection. but when i read the fine print, it straight up says any added underlayment voids the lifetime warranty. one supplier swears by floating it over 6mil poly anyway for uneven slabs, says warranties are bs and never honored. another tells me stick to the spec or eat the callback costs. whats the play here, pros? done this dance before?

stick to the manufacturer's spec every time. voided warranties mean pissed clients when planks cup or delaminate in a year.

ignore the warranty scare. i've laid thousands sq ft over underlayment and zero claims filed. just acclimate the planks 48 hours first.

had a job where we skipped it per instructions, then moisture from concrete wrecked the install in six months. client sued the supplier, they covered it but dragged feet. now i always add felt underlay if the spec allows, warranty be damned.

for uneven floors, grind the high spots first. underlayment hides issues but bites you later with click-lock failures.

coretec is solid, but test your slab's ph and moisture content before anything. if it's over 5lbs/1000sqft, no underlayment will save you without a subfloor barrier.

risk it if the client's budget is tight, but upsell a premium underlay that matches the warranty. i've turned warranty voids into add-on sales that way.