Good flooring installation starts well before the first plank is laid. Learn how installers assess existing floors, subfloor moisture and flatness, levelling, underlay, skirting, doors, appliances and possible preparation costs.
Choosing the flooring is the exciting part. Then someone mentions moisture readings, levelling, skirting and door clearance... then suddenly the job feels much more complicated.
Here is the reassuring part: these checks are normal. They help your installer work out what is beneath the existing floor, whether it is ready for the new flooring and what preparation should be included in the quote. A little investigation before installation can prevent movement, noise, damaged joints and expensive surprises later.
The short answer
Before flooring installation, the installer should confirm the selected product and method, inspect the existing floor, assess the exposed subfloor where possible, complete the required moisture and flatness checks, and plan the finished height and trims.
- Measure the rooms and inspect access.
- Confirm what must be removed and what may remain.
- Check the subfloor for moisture, damage and movement.
- Grind high areas, repair defects or fill low areas where required.
- Plan underlay or adhesive, expansion gaps, transitions, skirting or scotia.
- Check doors, appliances, cabinetry and adjoining floor heights.
- Clear the work area and agree on any variation process before installation starts.
If you are still comparing materials, start with our guide to hybrid, laminate, vinyl and engineered timber flooring. If you already have a product in mind, our guide to flooring thickness, wear layers, ratings and underlay will help you read its documents before this site assessment.
What is the subfloor? And why does it matter?
The subfloor is the structural surface that supports the finished flooring. It may be a concrete slab, plywood, particleboard or another approved structural floor. Tiles, carpet, laminate and old vinyl are usually floor coverings, even when a new floor might sometimes be installed over them.
Your new floor needs a suitable base. The exact requirements depend on the product and installation method, but manufacturers commonly require the supporting surface to be stable, dry, clean and sufficiently flat. A floating hybrid floor, glue-down vinyl and engineered timber do not necessarily have the same rules, so the selected installation guide matters more than a general rule of thumb.
Can new flooring go over existing tiles?
Sometimes, but “over tiles” should never mean “without checking the tiles”. The flooring manufacturer must allow the installation, and the tiled surface must be assessed as part of the complete floor system.
An installer may need to check:
- whether the tiles are secure, with no loose, hollow, badly cracked or moving areas;
- whether the surface is sufficiently flat for the selected flooring;
- whether grout lines, lipping or textured tiles need filling or smoothing;
- whether there is evidence of moisture or a leak beneath the tiled area;
- the combined height of the tiles, preparation, underlay or adhesive and new flooring; and
- the effect on doors, stairs, thresholds, appliances and adjoining rooms.
Going over sound tiles can reduce demolition, but it is not automatically the better or cheaper option. If the tiles are loose, the floor is uneven or the extra height creates other problems, removal may be the more reliable approach.
Which existing floors usually need to be removed?
| Existing covering | Can it sometimes remain? | What must be checked |
|---|---|---|
| Carpet and soft underlay | Generally no | Remove them so the structural surface can be inspected and properly prepared. |
| Floating laminate, hybrid or timber | Generally no | Many product guides require old floating floors to be removed rather than placing one moving system over another. |
| Sheet vinyl or linoleum | Sometimes | It may need to be securely bonded, non-cushioned, sound and permitted by the new flooring guide. |
| Ceramic or porcelain tiles | Sometimes | Bond, cracks, movement, grout lines, flatness, moisture and the finished floor height. |
| Old adhesive or coating | Only if approved | Compatibility, bond and contamination. Do not sand or disturb a material that may contain asbestos. |
These are starting points, not permission to install. For example, one manufacturer may allow a firmly bonded vinyl covering under a particular laminate system while another product may require it to be removed. Check the instructions for the exact range.
A safety note for older homes: some older vinyl floor tiles, sheet coverings, backing materials and adhesives can contain asbestos. You cannot confirm asbestos by appearance alone. If the material is suspected, particularly in a home built or renovated before 1990, do not sand, grind, drill or pull it up. Arrange appropriate testing and licensed advice first.
Why does moisture testing matter?
A floor can look dry and still contain or transmit enough moisture to affect an installation. Concrete can retain moisture or allow vapour to move through it. Timber and wood-based subfloors also need to be assessed for moisture and signs of leaks, poor ventilation or decay.
The correct test method, acceptable result and response depend on the flooring, adhesive, subfloor and manufacturer. If readings are outside the permitted range, the next step might involve more drying time, investigating an active moisture source or using an approved moisture-control system. A surface coating should not be used to hide an unresolved leak.
Ask your installer to record:
- what type of subfloor was tested;
- which test method and instrument were used;
- where and when readings were taken;
- the product manufacturer's permitted limit; and
- what preparation is required if the result is outside that limit.
When does a subfloor need levelling?
First, a useful distinction: flat and level are not quite the same. A floor can have a gradual slope and still be flat. Flooring instructions usually focus on how much the surface varies over a stated distance, because sudden high spots and hollows can leave planks unsupported or place extra stress on their joints.
The installer may grind high spots, patch isolated low areas, repair cracks, secure loose sheets or use a compatible smoothing or levelling compound. The permitted variation is product-specific. A tolerance quoted for one laminate or hybrid range should not be copied automatically to another.
Levelling is also not the same as correcting a structural problem. Significant movement, rot, settlement or cracking may need further investigation before a flooring installer can continue.
Can thicker underlay fix an uneven floor?
No; not when the unevenness is outside the product's permitted tolerance. Underlay may provide approved acoustic, moisture or comfort functions, and some systems can accommodate minor surface texture. It is not a substitute for grinding high areas or filling significant hollows.
Too much movement beneath a click floor can contribute to noise, flexing and stress at the locking joints. Adding a thicker or second underlay without written approval can also change how the floor performs and may affect the warranty. Use the underlay specified for the complete system.
Skirting or scotia: how will the edges be finished?
Many floating floors require a perimeter expansion space. It must remain free to do its job and then be covered neatly.
- Removing and refitting or replacing skirting can create a clean, built-in finish. It may involve extra labour, wall repairs or painting, especially when old skirting is damaged during removal.
- Scotia or quadrant can cover the expansion space without removing the existing skirting. It is fixed to the wall or skirting—not through a floating floor—so the floor remains able to move.
Neither approach is automatically right for every home. Agree on the profile, colour, corners, door frames and painting responsibility before accepting the quote.
What about doors, appliances and floor height?
A few millimetres can make a surprising difference. The installer should consider the full build-up of preparation, moisture treatment, underlay or adhesive and flooring, not the plank thickness alone.
Check internal and external doors, jambs, sliding-door tracks, stair nosings and transitions to other rooms. In kitchens and laundries, consider dishwasher, refrigerator and washing-machine clearances, kickboards and whether an appliance could become trapped by the new floor height. Permanent cabinetry and islands may also affect where a floating floor can run, depending on the product instructions.
Door trimming, jamb undercutting, appliance disconnection or cabinet changes may be separate trades or costs. It is much easier to identify them before the flooring arrives.
What should you do with furniture?
Do not assume furniture moving is included. Ask whether the installers need each room completely empty or whether they will move ordinary furniture in stages.
Before installation:
- remove small items, bedding, drawers, valuables and fragile objects;
- empty wardrobes or cabinets if they need to be moved;
- arrange specialists for pianos, aquariums, safes, pool tables or medical equipment;
- confirm who will disconnect and reconnect appliances; and
- keep children and pets safely away from tools, adhesives and active work areas.
Why can preparation costs change after removal?
A site measure can reveal a great deal, but an existing covering can hide dampness, cracks, loose boards, hollow tiles, old adhesive or unexpected height changes. The full condition may only become visible once removal begins.
| What may be discovered | Possible response | Why it can affect cost or timing |
|---|---|---|
| High spots or deep hollows | Grinding, patching or an approved levelling system | Additional materials, labour and curing time may be needed. |
| Moisture above the product limit | Find the cause, allow drying or specify an approved control system | Installation may need to pause until the cause and system are resolved. |
| Loose tiles, boards or sheets | Remove, repair or secure the affected area | The new floor needs a stable supporting surface. |
| Suspected asbestos-containing material | Stop disturbance and obtain appropriate assessment or testing | Specialist controls and licensed removal may be required. |
| Unexpected floor-height conflict | Alter transitions, trim doors or adjust affected joinery | This may involve extra finishing work or another trade. |
A clear quote should state what is included, what is based on an allowance and how additional work will be priced and approved. Useful items to confirm include removal and disposal, grinding or levelling, moisture control, underlay or adhesive, skirting or scotia, door work, furniture, appliances, transitions, stairs and site access.
A practical pre-installation checklist
- Confirm the exact flooring range, installation method and current installation guide.
- Ask what existing coverings will be removed, retained and disposed of.
- Confirm how the subfloor will be assessed for stability, flatness and moisture.
- Check what preparation is included and what remains provisional until the old floor is lifted.
- Calculate the finished height at doors, stairs, appliances and adjoining floors.
- Choose skirting or scotia and agree on trims, colours, painting and wall repairs.
- Confirm who moves furniture and disconnects appliances.
- For an apartment, obtain required strata approval, acoustic documents and access bookings before work begins.
- Ask how unforeseen work will be explained, priced and approved.
- Keep the product data sheet, installation instructions, care guide and warranty.
Ezymall's flooring renovation and installation service includes on-site measurement, so the product choice can be considered alongside the room dimensions, existing floor and finishing details. The final preparation scope should always be confirmed from the actual property and selected flooring system.
Frequently asked questions
Can hybrid or laminate flooring be installed over tiles?
Some products can be installed over tiles when the manufacturer permits it and the tiled surface is stable, dry, clean and sufficiently flat. The installer must also assess grout lines, loose tiles, moisture, overall floor height, doors and transitions. Approval is product- and site-specific.
Does every concrete slab need levelling before flooring?
No. It needs assessment against the flatness tolerance for the selected flooring. A suitable slab may need only cleaning and minor preparation; high spots, hollows or surface defects may require grinding, patching or a compatible levelling system.
Why test moisture if the concrete looks dry?
Appearance does not establish moisture condition. Moisture or vapour from a slab can affect adhesives, flooring and warranty compliance. The installer should use the test method and limit required for the selected product and installation system.
Can underlay fix an uneven subfloor?
Underlay cannot correct major unevenness outside the flooring manufacturer's tolerance. Its approved role may include acoustic, moisture or comfort performance, but significant high and low areas need proper preparation. Do not add extra or thicker underlay unless the installation guide allows it.
Is it better to remove skirting or use scotia?
Removing and refitting skirting can give a cleaner integrated finish but may add labour, painting or wall repairs. Scotia covers the expansion space without removing skirting. The best choice depends on the home, budget and desired finish.
Do flooring installers move furniture?
It depends on the quote and the type of furniture. Confirm this before installation. Small items and valuables should be removed, while pianos, aquariums, safes and some appliances may need specialist handling.
Why might preparation cost more than expected?
Old flooring can conceal moisture, cracks, loose materials, adhesive residue or uneven areas. Ask the quote to identify allowances and exclusions, then require your approval before any additional preparation proceeds.
Good preparation is part of the floor—not an optional extra
Customers naturally notice the colour and feel of a new floor. The installer is also thinking about the less visible details: what supports it, how dry and flat that surface is, where the floor can move, and whether every doorway and transition will still work.
Ask those questions before ordering and you will be in a much better position to compare complete quotes, understand genuine preparation costs and choose a flooring system that suits the home—not just the showroom sample.
