Floating vinyl plank and laminate still need continuous support. High and low areas can create movement, flexing, clicking, joint stress, poor edge alignment, hollow-feeling spots, visible waves, or difficulty locking the floor. Underlayment is not a general substitute for substrate correction.
Floating does not mean unsupported
The planks connect to each other while resting over the substrate or approved underlayment. Loads from walking and furniture still travel through the flooring into the surface below. Local voids or ridges can concentrate movement at the joints.
Flatness is measured over distance
A floor can look smooth from standing height while containing gradual humps or dips. Checking with suitable straightedges or other accepted methods across doorways and connected rooms reveals conditions that a small sample cannot show.
Underlayment has a defined job
Approved underlayment may provide cushioning, sound control, vapour-related function, or separation. Too much soft material can increase movement, and doubling an attached pad may violate product instructions.
Preparation methods vary
Concrete may need compatible grinding, patching, cleaning, priming, or levelling. Plywood may need fastener correction, patching, sanding or approved smoothing, and assessment of loose or damaged areas. Structural movement and moisture remain separate concerns.
Include flatness in the estimate
The scope should explain what area was assessed, what ordinary correction is included, which products or methods will be used, required cure, and what happens if removal reveals conditions outside the allowance.
Frequently asked questions
Can thick vinyl plank hide uneven concrete?
Thickness does not remove product flatness requirements. Click joints and the complete plank still need suitable support.
Can foam underlayment fill low spots?
Ordinary underlayment is not intended to fill significant low areas unless the product system specifically states otherwise.
Does the floor have to be perfectly level?
Not necessarily. It normally needs to meet the flooring system’s flatness and support requirements while preserving intentional slope where applicable.