Flooring planning
Flooring Underlayment and Transition Checklist
Beyond the flooring itself, most floating floor installs need underlayment unless the planks have an attached pad, a moisture barrier over concrete, a transition strip at every doorway or flooring change, and trim to cover the expansion gap around the room.
Open the flooring box calculatorUnderlayment and moisture
Start with the installation guide for your exact product, because the wrong underlayment can void the warranty.
- Attached pad: many vinyl plank and laminate products have one. Adding a second cushion layer is often not allowed.
- Separate underlayment: sold in rolls. Buy the same square footage as the flooring, plus about 10 percent for overlaps and trimming.
- Concrete subfloors: usually need a vapor barrier, typically 6 mil polyethylene sheet, even under waterproof planks.
- Wood subfloors: check for squeaks, loose panels, and height differences before anything goes down.
Transitions and trim
Walk the room and count every place the new floor ends or meets another surface. Each one needs a specific profile.
| Piece | Where it goes | How to count |
|---|---|---|
| T-molding | Between two floors of the same height | One per doorway |
| Reducer | Down to a lower floor such as sheet vinyl or concrete | One per doorway |
| End cap or threshold | Against sliding doors, carpet, or a fireplace hearth | Measure each run |
| Stair nose | Front edge of each step or landing | One per step, by stair width |
| Quarter round or baseboard | Covers the expansion gap at walls | Room perimeter minus door openings |
Subfloor flatness
Click-lock floors need a flat surface more than a level one. Manufacturers publish a tolerance, commonly around 3/16 inch over 10 feet. Check with a long straightedge, then sand high spots and fill low spots with a patching or leveling compound before install day.
Tools and small supplies
A basic floating floor install uses spacers for the expansion gap, a tapping block and pull bar, a saw for cross cuts, a jigsaw or oscillating tool for notches, a tape measure, and a pencil. An undercut saw for door casings makes the doorway cuts look finished.
If the manufacturer calls for acclimation, bring the sealed boxes into the room ahead of time and lay them flat for the stated period.
- Check whether your planks have an attached pad before buying underlayment.
- Count one transition for every doorway and flooring change.
- Fix subfloor flatness before the flooring arrives.
Run the numbers
The Flooring Box Calculator applies this math to your own measurements and shows each step. Best before buying boxed flooring at a home center or local flooring shop.