Luxury vinyl plank (LVP) has become the most popular flooring choice for Orléans and Ottawa homeowners — and for good reason. It's durable, waterproof on the surface, relatively affordable, and comes in a wide range of wood-look finishes. But LVP is more demanding about subfloor condition than most people realize, and the shortcuts that seem harmless during installation tend to show up as problems within a year or two. Here's what proper prep actually looks like.
Why LVP Prep Is Different from Tile Prep
Tile is set in a mortar bed that bridges minor surface variation and locks the tile in place. LVP is a floating floor — it clicks together and rests on top of the subfloor without being glued down. That flexibility sounds forgiving, but it's not. Because LVP floats, it follows the shape of whatever is underneath it. High spots in the subfloor become high spots you feel underfoot. Low spots create hollow areas where the floor gives slightly when you walk over them, causing the locking joints to fatigue over time.
The wear layer on the surface of the plank amplifies this effect visually too — raking light across a poorly prepped LVP floor reveals every irregularity in the substrate below.
Flatness Requirement: 3/16" in 10 Feet
The industry standard for LVP subfloor flatness is no more than 3/16" variation over any 10-foot span, or 1/8" over 6 feet. These numbers come from the manufacturer specifications — check the installation guide for whatever product you're using, because some premium LVP products have tighter tolerances.
To measure: use a 10-foot straightedge or a long level laid flat against the floor. Slide it around the room systematically and mark any area where light passes underneath by more than 3/16". Those areas need attention. High spots get ground flat with an angle grinder fitted with a diamond cup wheel or a floor grinder — dust control is important here, particularly over concrete. Low spots get filled with a floor-leveling or patching compound appropriate for the substrate. Let it cure fully before proceeding.
Skipping this step because a floor "looks pretty flat" is a common mistake. Floors that look flat from standing height often have variations of 1/4" or more when you get down with a straightedge. Take the measurement.
Moisture: Waterproof Above, Not Below
LVP won't absorb water through its surface — that's one of its biggest selling points. But this creates a false sense of security about moisture. The subfloor underneath can still be a problem.
Over a concrete slab, moisture vapour transmitting upward through the concrete can cause adhesive failure in glue-down installations and can promote mold growth in the air space under a floating floor. Before installing LVP over concrete, test moisture levels. A pin-type or pin-less moisture meter gives a quick surface reading. For more accurate long-term data, a calcium chloride test or in-situ relative humidity test (per ASTM F2170) measures the moisture emission rate of the slab over time. Most LVP manufacturers specify a maximum moisture emission rate — stay under it or use a vapour barrier appropriate for the conditions.
Over wood subfloors, elevated moisture content causes swelling and movement that stresses the floor above. A wood subfloor should read below 12% MC before installation, and ideally within a few percentage points of the LVP panels' acclimated state. If a wood subfloor is reading high, find the moisture source and fix it — don't install over it.
Acclimation
LVP is manufactured to a fixed dimension, but its core (typically SPC — stone polymer composite, or WPC — wood polymer composite) responds slightly to temperature changes. Before installation, boxes of LVP need to be stored flat in the room where they'll be installed for a minimum of 48 hours. This lets the material reach equilibrium with the room's temperature.
In Ottawa's climate, this is especially important in winter when materials are brought in from a cold vehicle or storage space, and in summer when humidity swings significantly. A plank installed cold in January will expand slightly as the room heats up — if there's no room for that expansion, the floor buckles. 48 hours isn't a suggestion; it's a requirement that every major LVP manufacturer includes in their installation guidelines.
Expansion Gaps
Every floating floor needs a perimeter expansion gap — space between the edge of the flooring and every fixed vertical surface. For most LVP, this is 1/4" around all walls, door frames, cabinetry, islands, columns and any other fixed object. The baseboard or quarter-round covers this gap once installation is complete.
Forgetting expansion gaps is the most common installation error on DIY LVP projects. The floor looks perfect on day one. Then summer arrives, the temperature climbs, the floor expands — and with nowhere to go, it buckles up at the joints or in the middle of the room. The entire floor has to come up to fix it. Gap at every wall. Every fixed object. Every time.
Underlayment: Pre-Attached vs. Separate
Many LVP products come with underlayment pre-attached to the bottom of each plank. This provides a modest acoustic benefit and adds a small amount of cushion underfoot. If the product has pre-attached underlayment, do not add a second layer of underlayment underneath it. Double underlayment makes the floor feel spongy, causes the locking joints to flex excessively, and can void the manufacturer warranty.
If the product does not include pre-attached underlayment, a thin (2-3mm) foam or felt underlayment is typically installed loose across the subfloor before the first row of planks. On concrete where vapour is a concern, a vapour-barrier underlayment that combines both functions is the right choice.
Planning Transitions Before You Start
Before the first plank goes down, walk through every doorway and think about how the floor transitions to the next room. LVP to tile requires a reducer or a Schluter-style transition strip. LVP to carpet requires a carpet bar. LVP to LVP in a doorway typically gets a T-bar to allow both rooms to float independently. Getting the transition hardware ordered and on-site before starting saves a lot of headache at the end of the job.
For professional LVP installation in Orléans and Ottawa, see the vinyl plank installation service page or the luxury vinyl plank service overview for Ottawa.