The finished flooring can only follow the surface and structure below it.
Subfloor preparation may include cleaning, fastening, patching, scraping, grinding, filling, smoothing, or using an approved levelling product. The correct work depends on whether the substrate is concrete, plywood, an existing approved surface, or a more complex assembly, and whether the new flooring is flexible, floating, fastened, bonded, or tiled.
Where this service is often considered
- Low or high areas before floating floors
- Concrete slab preparation
- Plywood fastening and minor repair
- Tile and glue-down surface preparation
Flat, level, smooth, rigid, and dry describe different conditions.
A floor may be intentionally sloped but sufficiently flat, visually level but wavy, smooth but structurally weak, or dry at the surface while failing a product’s moisture requirements.
Patching and smoothing
Small voids, joints, fastener areas, adhesive scars, and surface imperfections are treated with compatible materials for the planned floor.
Flatness correction
High and low areas are identified over the relevant distances and corrected by approved grinding, patching, or levelling within the agreed scope.
Subfloor fastening or repair
Accessible loose plywood, damaged sections, squeaks, fasteners, seams, and deflection concerns are assessed separately from structural work.
Preparation begins with the flooring system that will be installed.
Vinyl, floating laminate, hardwood, carpet, and large-format tile do not have identical substrate tolerances or assembly requirements.
- Identify substrate material and thickness
- Confirm the new flooring system
- Map high, low, damaged, or loose areas
- Review cracks and moisture conditions
- Protect drains and intentional slopes
- Use compatible preparation products
What the estimate can separate clearly
A useful flooring scope distinguishes the visible installation from removal, substrate work, material responsibilities, finishing, and conditions that cannot be confirmed until the existing floor is exposed.
Assessment
Record substrate, accessible construction, flatness observations, cracks, damage, old adhesive, moisture history, slopes, drains, and floor height.
Included correction
State the measured area, method, products, thickness, grinding, patching, levelling, fastening, and cure requirements included.
Exclusions
Separate structural repairs, active water entry, major subfloor replacement, joist work, hazardous material, mould, and conditions hidden until removal.
Flooring handoff
Confirm cleanliness, readiness, moisture requirements, primer, underlayment, adhesive, mortar, and the point at which installation can begin.
Self-levelling material does not make every floor automatically level.
Product selection, primer, substrate, mixing, flow, dams, drains, thickness, transitions, cure, and intended elevation all require planning. Some floors need flatness improvement without eliminating necessary slope.
Three ways to start
- Flooring already purchased: confirm product, quantity, accessories, substrate, and installation instructions.
- Supply and installation: define the room and performance requirements before material is sourced.
- Installation only: confirm the installation conditions before purchasing the final quantity and accessories.
Questions about subfloor preparation
What is the difference between flat and level?
Flat describes surface variation over a distance; level describes relationship to horizontal. A floor can be sloped but flat, or visually level while containing local high and low areas.
Can floor levelling fix every uneven floor?
No. Structural movement, weak framing, major elevation changes, drainage slope, damaged concrete, moisture, limited ceiling height, stairs, and doors can require a different solution.
Do floating floors need a flat subfloor?
Yes. Floating floors still rely on the substrate to support joints and distribute load. Excess variation can create movement, noise, stress, or visible irregularity.
Can squeaks be fixed before new flooring?
Accessible squeaks may sometimes be reduced by fastening or repair, but the source can involve joists, blocking, movement, plumbing, ducts, or inaccessible construction.
Is moisture testing part of preparation?
Moisture requirements depend on the substrate, product, adhesive, room, and manufacturer instructions. Any testing included in the project should be identified in the scope.