A scratch in the coating, a chip in the timber, a stable gap, a moving board and a hollow area beneath a bonded floor are five different repairs. Choosing by colour or gap size alone can hide the symptom while leaving the cause untouched. Identify what has failed first, then choose the product that matches the timber, movement, finish and subfloor.
Repair the cause before the appearance
If a floor is lifting, moving, repeatedly cracking, damp or debonding across a large area, stop before filling it. WWFS recommends assessment and repair by an experienced wood-floor professional. Always read the current flooring, repair-product and finish instructions, as these take priority over this general guide.
Quick repair-product selector
| What has gone wrong? | Product or route to assess | Important limitation |
|---|---|---|
| Light surface mark, dull patch or care-product build-up | Use the correct cleaner, maintenance or polish-removal process for the existing finish | Do not cut into an intact coating or fill it with wax before confirming whether it is only a surface mark |
| Small chip, dent or deep cosmetic scratch in a finished floor | Complete hard-wax repair kit, or a Morrells hard-wax set and melting tool | A wax repair disguises local lost material; it does not recreate the original factory coating or repair structural movement |
| Very small cosmetic defect in a low-wear position | Morrells Soft Wax Repair Stick Set | Soft wax is easier to apply but is less suitable for a heavily trafficked floor repair |
| Pin hole, nail hole or small stable defect in bare interior timber | Morrells One-Part Coloured Wood Filler | Not for rebuilding broken edges, corners, large voids or moving joints |
| Fine stable joints across a floor being fully sanded | Bona, Morrells or Lecol sanding-dust filler selected from the comparison below | These products are part of a complete bare-wood sanding sequence, not a spot filler for a factory-finished floor |
| Wider stable gaps between traditional pine boards | Reclaimed pine slivers with compatible PVA, or the sliver and PVA bundle | Secure loose boards and assess seasonal movement before gluing timber into every joint |
| Neat flexible detail at a skirting, threshold or adjoining material | Bona Gap Master, Bostik 3070 Liquid Cork or a correctly sized cork strip | Never eliminate the movement space required by the flooring manufacturer |
| Loose or squeaking structural floorboard | Diagnose the joist, board and hidden services, then use the correct repair and fixing route | Filler cannot secure a moving board |
| Individual loose parquet block | Lift, prepare and re-bond with the adhesive approved for the block, residue and subfloor | Old black adhesive needs assessment; do not sand or grind unidentified bitumen |
| Local hollow area beneath previously bonded wooden flooring | Bona R200 with a Janser adhesive syringe | Professional, localised repair only; not a cure for widespread adhesive or subfloor failure |
| Hole, crack or imperfection in the subfloor beneath the wood | Use the correct F. Ball repair or finishing compound for the substrate and depth | Wood filler and floor wax are not subfloor repair products |
Diagnose the problem before choosing a filler
Cosmetic damage
The floor is sound and stable, but the finish or a small area of timber is marked, dented or chipped. A colour-matched wax or small timber filler may be appropriate.
Timber movement
A board deflects, squeaks, opens and closes seasonally or has lost support. Find and correct the movement before making the visible repair.
Adhesive failure
A bonded block or board sounds hollow, moves or lifts. Decide whether the failure is isolated or widespread and whether contamination, moisture or poor transfer is responsible.
Subfloor failure
Cracks, loose screed, unsupported panel joints or moisture beneath the wood require a compatible subfloor system, not a surface filler.
Check whether the defect changes with the seasons, whether nearby boards move under load, whether the area is close to a leak or external door, and whether the floor is solid, engineered, parquet or floating. Record the existing finish as lacquer, penetrating oil, hardwax oil or unknown. This determines whether a local repair can be blended or whether a board, section or wider coating area needs treatment.
A colour match is not a finish match
Timber species, stain, ageing, grain, sheen and the final oil or lacquer all affect the result. A filler that matches bare wood can change noticeably after coating. Always make a representative colour and finish test before repairing a prominent area.
Scratches, dents, chips and wax repairs
Wax repairs are useful where a small amount of material has been lost from an otherwise stable floor. They are particularly helpful on prefinished boards where sanding a tiny defect could enlarge the visual difference. Clean the defect, remove loose fibres and build the colour gradually rather than trying to match the floor with one solid block.
Hard wax or soft wax?
| System | Best suited to | How it is applied | Main limitation |
|---|---|---|---|
| Hard wax | Small chips, dents and deeper cosmetic defects where a firmer repair is needed | Melt small amounts into the defect, allow to cool, then level carefully | Requires a melting tool and practice; colour and sheen still need blending |
| Soft wax | Very small cosmetic defects and low-wear positions | Press or rub into the clean defect, remove excess and buff | Softer repair, so not the first choice for deeper damage in a busy walking area |
| One-part coloured filler | Pin holes, nail holes and small stable imperfections in bare interior timber | Knife into the defect, allow to harden and sand | Not for an intact prefinished surface, large missing edges or movement |
Complete hard-wax kit
The Wood Floor Hard Wax Scratch & Dent Repair Kit provides a melting tool, eleven blendable wax colours and the small preparation and levelling accessories needed for an occasional repair. It is the simplest route when the customer has no existing wax equipment. The melting tool requires two AA batteries, which are not included.
Professional Morrells hard-wax system
For repeat work, select the Morrells Assorted Light Hard Wax Set for pale timber and lighter finishes, or the Morrells Assorted Dark Hard Wax Set for darker timber and stains. Use them with the battery-powered hard-wax melting tool, which includes batteries and a detachable levelling scraper.
- Clean and dry the repair. Remove loose fibres without enlarging the damage.
- Start with the closest base shade, then add small amounts of lighter or darker wax.
- Recreate grain with more than one colour where the surrounding timber is varied.
- Fill slightly proud, let the wax cool fully, then level it without scratching the coating.
- Adjust the final sheen carefully. A perfect colour with the wrong sheen can remain visible.
Morrells Professional Soft Wax contains twenty blendable colours and can be applied without heating. Use it for light-duty cosmetic repairs. Choose hard wax for a firmer burn-in repair on a suitable trafficked surface.
Wax does not reinstate the original coating
A wax repair can disguise a chip, but it does not recreate a continuous factory lacquer, oil system or product warranty. Damage through the finish, water-sensitive areas, repeated chipping and large crushed edges may require professional local coating work or replacement of the affected board.
Resin fillers mixed with sanding dust
Sanding-dust fillers are liquids or binders mixed with fine, clean dust from the floor. They are spread across bare timber during a complete sanding process, allowed to dry and sanded before the chosen finish. They are ideal for stable parquet joints, nail holes, shakes and fine defects, but they are not interchangeable with ready-mixed coloured filler or flexible sealant.
| WWFS product | Key difference | Stated joint guidance | Best starting point |
|---|---|---|---|
| Bona Mix & Fill | Waterborne acrylate binder, available in 1L and 5L; suitable with Bona lacquer and oil systems | Up to approximately 2mm | Fine joints and imperfections on light or dark timber where a Bona finishing system is planned |
| Bona Mix & Fill Plus 5L | Higher-solids waterborne binder with greater filling capacity; especially recommended for light to medium timbers | Up to approximately 3mm; gaps over 2mm need longer drying | Newer or restored oak, beech, pine and maple floors needing greater fill than standard Mix & Fill |
| Morrells Mix & Fill | Cellulose-based binder in 1L and 5L; mixed at roughly one part binder to one or two parts dust | Up to approximately 5mm wide or deep where the defect is stable | Full-floor filling within a Morrells Induro or compatible professional finishing sequence |
| Lecol 7500 | Water-free synthetic-resin binder in 0.8kg and 5kg; very fast drying with strong adhesion | Use for fine, stable floor joints and follow the current technical sheet rather than assuming a universal maximum | Fast professional parquet and wood-floor sanding work where a water-free binder is preferred |
How to use sanding-dust filler correctly
- Sand the floor back to clean, bare timber before filling.
- Use fine, clean dust from the same timber and floor. Do not use coarse dust or dust contaminated with old coating, adhesive, metal or another species.
- Follow the product's mixing ratio. Too much dust can make a dry, weak mix; too little can increase shrinkage and colour variation.
- Spread with a clean stainless-steel flat blade, work from several directions and remove heavy ridges.
- Let deep or wide repairs dry fully. A dry surface skin does not prove the centre is ready to sand.
- Sand off every surface residue before staining, priming, oiling or lacquering.
A Bona Flat Bladed Trowel is the appropriate application tool for full-surface filling. The exact sanding stage and abrasive must follow the filler and finish system.
Do not resin-fill a floor that is designed to keep moving
Bona specifically warns that plank and end-grain floor gaps are not normally filled because expansion and contraction can break the dried filler loose. Wider seasonal floorboard gaps may need timber slivers, while required movement joints need cork, a profile or another approved flexible detail.
Traditional floorboard gaps and pine slivers
Reclaimed Pine Slivers are tapered wedges made from reclaimed pine, approximately one metre long and supplied in 6mm or 8mm sizes. They are designed for wider gaps in suitable traditional pine and softwood floorboards. Once bonded, the projecting timber is trimmed, sanded and finished with the floor.
The Pine Slivers & Morrells PVA Gap Repair Bundle contains two approximately 100-piece sliver packs and two 1kg bottles of Morrells D3 PVA. It is the complete route when a larger floorboard restoration needs both timber and adhesive.
Before installing slivers
- Secure loose boards and repair unsupported ends first.
- Locate pipes, cables and joists before adding screws or nails.
- Remove old loose filler and contamination from the joint sides so the adhesive bonds to sound timber.
- Assess the floor through normal indoor conditions where possible. A gap at the driest point of the year may close when humidity rises.
- Check that filling the joints will not interfere with the building's moisture or ventilation strategy.
- Use the tapered section that fits the actual joint; do not force an oversized sliver hard enough to distort the boards.
PVA is a timber adhesive, not a void-filling repair. The joint sides need contact with the sliver. Allow the adhesive to cure before trimming, and take care not to cut deeply into old boards or reduce their thickness unnecessarily.
Flexible joints, liquid cork and cork strips
A movement joint is not simply an untidy gap. It exists so the floor can expand and contract without pushing into walls, hearths, thresholds or adjoining finishes. The product must preserve the movement required by the flooring manufacturer.
| Product | Best suited to | Key specification | Do not use it as |
|---|---|---|---|
| Bona Gap Master 310ml | Colour-matched joints at skirtings, thresholds, frames and similar wood-floor details | Silicone-free acrylic with up to 15% movement tolerance; can be overcoated with Bona lacquer after drying | A rigid replacement for the whole perimeter expansion gap or a full-floor gap filler |
| Bostik 3070 Liquid Cork 500ml | Irregular joints around hearths, door frames and transitions between different flooring materials | Natural cork in a flexible binder for joints up to approximately 5mm; applied with a compatible foil-sausage gun | A repair for loose boards, structural cracks or gaps larger than its stated limit |
| Cork Expansion Strips, pack of 10 | Straight, planned movement joints where a solid strip gives a controlled edge | 910mm lengths in 8 × 12mm, 10 × 10mm, 10 × 14mm or 12 × 20mm | A way to remove the minimum expansion allowance specified for the floor |
| Bulk Cork Expansion Strips | Larger installations needing the same straight joint detail | Same size range in bulk packs of 30, 64 or 80, depending on section | A cosmetic plug for random moving gaps between unsupported boards |
For a deep sealant joint, follow the manufacturer’s backing-material and joint-shape instructions. Bona’s current Gap Master guidance requires suitable backing to avoid adhesion on three faces. Mask both edges, tool the product promptly and allow it to cure before sanding or coating where permitted.
Loose boards, squeaks and parquet repairs
Loose or squeaking structural floorboards
A squeak can come from a board moving on a joist, an unsupported end, a loose panel, boards rubbing together or a service moving below the floor. A visible crack is not necessarily the cause. Where a suitable board crosses a known sound joist and hidden services have been located, Floor-Tite anti-creep screws may form part of the repair. Fill the screw recess only after the movement has stopped.
Use the complete loose and squeaking floorboard guide and the screws, nails, cleats and staples guide. A coloured filler, wax or resin paste is cosmetic and cannot replace a structural fixing.
Replacing a damaged plank or board
Replacement is often the most reliable repair for a split tongue, crushed edge, large burn, deep water damage or a factory-finished board with extensive coating loss. Match the exact product and batch where possible, check the wear-layer depth before cutting, and plan how the board is locked, bonded or secret-fixed.
For a clean, correctly prepared bonded repair, a small controlled pack such as Bona R848T 1kg sausage may be more practical than opening a full tub. The adhesive still has to be approved for the particular flooring, subfloor and repair method. Do not bead-bond a board where the system requires full adhesive transfer.
Loose parquet and old black adhesive
Individual parquet blocks can often be lifted, cleaned as far as safely possible and re-bonded. Lecol 5500 is a traditional water-free synthetic-resin parquet adhesive stocked in 6kg and 16kg packs, and is used by flooring professionals for suitable local block-repair work. This does not mean every old bitumen-coated floor can be glued straight back.
Do not sand or grind unidentified black residue
Older bituminous adhesives may contain asbestos. A widespread residue, damp base or failing installation needs professional assessment and an approved preparation or encapsulation system. Lecol’s current refurbishment guidance recommends removing only loose material safely and creating a new prepared subfloor rather than abrading old bitumen. Follow the dedicated parquet and old-bitumen repair guide.
Where the blocks and base can be taken back to a clean, sound, compatible condition, a modern flexible parquet adhesive may be selected instead. Use the wood-flooring adhesive guide rather than choosing solely by the original adhesive colour.
Bona R200 for local hollow spots
Bona R200 Hollow Spot Repair Resin 0.53kg is a one-component polyurethane liquid for filling a local void and re-attaching a loose parquet element or board beneath previously bonded wood flooring. It expands slightly into a foam, creating a new bond between the underside of the timber and the subfloor.
When R200 is the right repair
- The floor was intended to be fully bonded.
- The hollow or loose area is isolated and can be mapped accurately.
- The surrounding flooring, adhesive and subfloor remain sound.
- Moisture, contamination, excessive deflection and wider bond failure have been ruled out.
- The drilling and injection point can be chosen without damaging underfloor heating, pipes, cables or the board structure.
What the repair normally involves
- Tap and mark the actual limits of the hollow area; do not inject every area that merely sounds different.
- Protect the finished surface and joints with suitable masking.
- Following Bona’s method, drill a discreet access hole of approximately 4mm through the flooring only.
- Use a Janser Flooring Adhesive Syringe to inject Bona R200 slowly beneath the board.
- Avoid over-injection. Expanding material can escape through joints or raise the flooring.
- Apply an even weight while the new bond forms, following the current Bona instructions.
- After curing, repair the access hole with a colour-matched plug, hard wax or other finish-compatible method.
R200 is a professional chemical repair
Bona R200 is a polyurethane product containing reactive isocyanates. Read the current label, technical sheet and UK safety data sheet before use, and follow all required training, ventilation and personal-protection measures. Do not use it as a casual household filler or where the cause of widespread hollowing is unknown.
A local injection can save unnecessary board removal, but it cannot correct a contaminated screed, missing adhesive across the room, a damp subfloor, excessive undulation or a floating floor that was never meant to be bonded.
Repairs beneath the wood floor
Subfloor compounds are included here because a sound timber repair depends on the base beneath it. They must not be confused with timber fillers.
| Subfloor problem | WWFS product to assess | Correct role |
|---|---|---|
| Deeper local hole, damaged screed, step, ramp or internal mineral repair | F. Ball STOPGAP 400 Repair 10kg | Slump-free repair compound for suitable internal bases, normally 2–50mm depending on the approved mix |
| Screw-head marks, plywood joints, feather edge or fine imperfection | F. Ball STOPGAP Micro Rapid 8kg | Flexible finishing compound for suitable securely screw-fixed plywood, hardboard and other approved absorbent bases |
| Sound old adhesive residue requiring a compatible renovation layer | F. Ball STOPGAP 1200 Pro | Specialist smoothing compound approved over sound old adhesive residues including bitumen, subject to moisture and full system checks |
STOPGAP Micro Rapid can smooth screw heads and supported panel joints; it does not strengthen loose plywood. STOPGAP 400 repairs suitable internal mineral bases; it is not a wood-floor gap filler. For moisture, primer, DPM, flatness and overlay requirements, use the subfloor preparation guide and moisture, DPM and primer guide.
When the finish is damaged rather than the timber
A grey mark, dull area or visible scratch may be contamination, care-product build-up, a scratch within the coating or damage through to the wood. Each needs a different response.
- Surface contamination: use the cleaner approved for the existing oil or lacquer.
- Old polish build-up: use the matching removal process before applying more polish.
- Dry or worn oiled surface: clean and maintain with the exact compatible oil system; do not coat over dirt or another unknown product.
- Scratch within lacquer: a professional clean and recoat may be more suitable than filler, but adhesion preparation and coating identity are essential.
- Damage through to timber: assess colour, lost material and moisture protection. A wax repair may disguise a small chip; larger damage may need board-level repair or sanding and refinishing.
Use the cleaning and maintenance guide and wood-floor finish-system guide before applying a care product as a “repair”. Polish and refresher products improve appearance; they do not rebuild missing timber or fix adhesion.
Common wood-floor repair mistakes
Filling movement
Rigid filler is placed into a gap that opens and closes, so it cracks, powders or transfers stress into the board edge.
Using wax on a loose board
The surface looks better briefly, but the unfixed board keeps moving and the cosmetic repair fails.
Using dirty sanding dust
Dust from old coating, another timber or a coarse sanding stage produces weak filler and an obvious colour mismatch.
Choosing only by gap width
A 3mm stable parquet joint and a 3mm seasonal plank gap can need completely different repair methods.
Eliminating expansion space
A movement joint is packed rigidly to make it disappear, leaving the floor nowhere to expand.
Over-injecting R200
Too much expanding resin can escape through the joints, mark the finish or push the board upwards.
Abrading black residue
Unidentified old bitumen is sanded or ground without assessment, potentially disturbing hazardous material.
Skipping the finished test
The filler matches bare wood but changes under stain, oil or lacquer and becomes more visible than the original defect.
Wood-floor repair FAQs
Can I fill every gap in a wooden floor?
No. Stable fine parquet joints can often be filled during sanding, but seasonal plank gaps, required expansion joints and gaps caused by loose boards need different treatment. Identify why the gap exists before filling it.
What is the difference between Bona Mix & Fill and Mix & Fill Plus?
Standard Bona Mix & Fill is for fine joints up to approximately 2mm and can be used on light or dark timber. Plus has higher solids and greater filling capacity up to approximately 3mm, and is especially recommended for light to medium species such as oak, beech, pine and maple.
Can sanding-dust filler be used on a prefinished floor?
Not as a simple spot repair. These binders are designed to be applied to bare timber and sanded clean before a compatible finish is installed. Use a wax repair, professional local coating repair or replacement-board route for suitable prefinished damage.
Are pine slivers better than filler?
For wider stable gaps in suitable traditional pine boards, slivers normally form a stronger timber repair than resin paste alone. They are not suitable until loose boards, contamination and seasonal movement have been assessed.
Can Bona Gap Master fill gaps between every floorboard?
No. Its primary use is a flexible, colour-matched joint at skirtings, thresholds and similar details. It does not replace the required perimeter expansion space and should not be trowelled across a whole boarded floor as if it were sanding-dust filler.
Will Bona R200 fix a hollow floor?
It can re-bond a suitable isolated hollow area beneath previously bonded wood flooring. It is not intended for widespread hollowing, a floating floor, a damp or contaminated base, poor flatness or extensive adhesive failure.
Can I glue parquet straight over old bitumen?
Do not use that as a general rule. A local like-for-like block repair and a full refurbishment are different. Assess the residue, moisture and subfloor, never abrade unidentified black adhesive, and follow current adhesive and preparation-system guidance.
Is white lightweight filler suitable for a wooden floor?
No. Products such as lightweight decorating filler and decorators' caulk are for the stated decorating or trim applications. Use a purpose-made timber, wax, joint or subfloor repair product for the defect.
Related WWFS guides
- How to repair loose and squeaking wooden floorboards
- How to repair and relay parquet blocks with old bitumen
- Which wood-floor screw, nail, cleat or staple should I use?
- Which wood-floor installation method should I use?
- Which wood-flooring adhesive should I choose?
- How to prepare a subfloor for engineered wood flooring
- How to test moisture and choose a DPM or primer
- Which floor cleaner or maintenance product should I use?
- Which wood-floor finish system should I use?
Still unsure what has failed?
Send WWFS clear photographs, the floor type and finish, approximate age, whether it moves under pressure, the gap or defect size, subfloor information and any recent leak or humidity change. Those details are more useful than choosing a filler by colour alone.