Wood Floor Gap Filling London

Wood Floor Gap Filling London

Gaps between floorboards are one of the most common problems we see in London properties. Victorian and Edwardian houses in particular develop them as the original pine boards shrink and move over decades. Even newer hardwood floors can gap if the moisture content was wrong at installation or if the sub-floor has flexed. The good news is that most gaps are fixable, and the right method depends on gap size, board type, and how the floor is fixed down.

We carry out gap filling across all London boroughs, usually as part of a floor sanding and finishing project. Call us on 020 8830 9782 or book a free site visit and we will assess which approach suits your floor.

Why Gaps Form in Wooden Floors

Wood moves with changes in temperature and humidity throughout the year. In winter, central heating dries the air and boards contract, opening gaps. In summer, humidity rises and boards swell back. Over time, if the boards are loose or were laid with insufficient acclimatisation, the cycling causes permanent gapping.

Other common causes include:

• Old or under-fixed boards that have shifted on the joists
• Sub-floor movement or settlement
• Boards that were never properly nailed through the tongue
• Water damage that caused cupping or shrinkage

Before filling anything, we check whether the floor needs re-securing. Filling gaps in a loose or bouncy floor is a short-term fix. Boards need to be stable before any filler is applied.

Gap Filling Methods We Use

Resin and Sawdust (Gaps Up to 5mm)

This is the most common method for gap filling on parquet floors and tongue-and-groove floorboards where the gaps are narrow. During the sanding process we collect fine sawdust from your floor. That sawdust is mixed with a clear flexible resin to produce a colour-matched paste, which is applied with a spatula and worked into the gaps. Once dry it is sanded flat, leaving a surface that blends naturally with the surrounding boards.

The resin we use remains slightly flexible when cured, which allows for a degree of seasonal movement without cracking. That said, on old solid pine boards over open joists, any filler is working against significant movement. We will tell you honestly if resin filling is unlikely to last in your specific floor.

Cost: from £7 to £9 per square metre, typically added to a sanding job.

Flexible Acrylic Filler (Original Pine Floorboards)

For original pine floorboards in Victorian and Edwardian houses, we often recommend a flexible acrylic mastic filler rather than rigid resin. Acrylic filler stays flexible after curing, which means it moves with the board rather than cracking out in winter. It comes in a range of wood tones and can be colour-matched reasonably well to aged pine.

Acrylic filler is particularly useful when the gaps are inconsistent in width or the boards have uneven edges. It does not sand as cleanly as resin, so on floors that are being heavily sanded it is applied after the main sanding passes.

Cost: included within resin filling price range; typically £7 to £10 per square metre depending on gap density.

Wooden Strips (Gaps Over 5mm)

Where gaps are wider than 5mm, and especially where they are consistent along the full length of the board, we cut thin timber slivers to fit and glue them in place. The strips are slightly oversized, glued with wood adhesive, tapped home, and left to set overnight. The following day they are planed and sanded flush with the surrounding floor.

Wooden strip filling is more labour-intensive than resin but gives a result that is structurally solid and visually cleaner on wide gaps. The strips sit on the joists where they cross them, so there is no risk of them dropping through. On solid base floors, adhesive alone holds them securely.

This method is better suited to floors that have reasonable board stability. On a floor with a lot of movement, even wooden strips can work loose over a few seasons if the boards are flexing significantly.

Cost: from £11 to £15 per square metre.

Resin Injection (Localised Repairs)

For localised gaps around knots, splits in boards, or isolated areas where the gap is very narrow but deep, we use a low-viscosity resin injected directly into the gap. It flows in, fills the full depth, and sets hard. This is particularly useful on parquet blocks where surface application would not penetrate properly.

Injection filling is not suitable for filling large continuous gaps between boards — it is a targeted repair tool. Combined with surface resin or filler it can produce an excellent result on damaged or aged parquet.

What Happens on the Day

Gap filling is done in stages alongside or just before the floor sanding process.

1. We assess the floor and confirm the method. Any loose boards are re-secured with screws or lost-head nails before filling starts.
2. Sanding begins. During early sanding passes we collect sawdust for the resin mix.
3. After the first coarse pass, gap filling is applied. The floor is left to cure — typically two to four hours for resin, overnight for wooden strips.
4. Final sanding passes bring the filler flush with the surface. Inspection pass confirms an even surface before finishing.
5. Your chosen finish — lacquer, hardwax oil, or Danish oil — is applied over the prepared surface.

You do not need to be present throughout the day. We work independently and leave the property clean at the end of each session.

Gap Filling Costs in London

Gap filling is almost always carried out as part of a sanding job rather than as a standalone service. Typical pricing:

• Resin and sawdust filling: £7 to £9 per m²
• Flexible acrylic filler: £7 to £10 per m²
• Wooden strip filling: £11 to £15 per m²
• Sanding plus gap filling for a 20 m² room: approximately £450 to £700 depending on method and finish selected

We offer a free no-obligation site visit and written quote. There are no hidden extras — the quote covers everything unless unforeseen structural work is discovered.

Frequently Asked Questions

How wide do gaps need to be before they are worth filling?

Any gap wider than 2mm is worth filling if it bothers you aesthetically or causes draughts. Below 2mm is within normal seasonal movement range and filling is unlikely to produce a lasting result. We will advise during the site visit whether filling makes sense for your specific floor.

Can gap filling be done without sanding the whole floor?

It can, but results are usually poor. Filler applied to an uneven or dirty surface does not bond reliably and is difficult to finish to a consistent level. For spot repairs on a floor that was recently sanded and is otherwise in good condition, localised filling is fine. On an older floor, combining gap filling with sanding gives a much better result.

Will the filler match my floor colour?

Resin mixed with your floor's own sawdust gives the closest colour match possible. The sawdust from your boards is the same species, age, and stain level as the floor itself. Acrylic filler is a close but not perfect match. Wooden strips are cut from timber matched to your floor species where possible. Nothing is invisible under raking light, but on a finished and sealed floor the filled gaps are generally not noticeable.

Does gap filling stop cold draughts coming through the floor?

Yes, it reduces them significantly. Gaps in suspended timber floors allow cold air from the void beneath to enter the room. Filling them — particularly with a flexible or wooden strip method — cuts air infiltration. If draughts are your primary concern we can also discuss draught proofing the perimeter of the floor and the gaps around pipes.

How long does gap filling last?

Wooden strip filling on a stable floor can last 10 to 15 years or longer before any visible gaps reappear. Resin filling on a floor with moderate movement typically lasts 5 to 8 years. Flexible acrylic on original pine is generally the most durable option on floors with high seasonal movement. No filler is permanent on a floor that moves significantly — that is the nature of solid wood.

Do I need to move furniture before you arrive?

We ask that the area is clear of furniture before the team arrives. We do not move heavy pieces such as wardrobes, beds, or bookcases loaded with contents. Light furniture and rugs should be removed. We can advise on this when booking.

Ready to get a quote? Call 020 8830 9782 or book your free site visit online. We cover all London boroughs and typical lead times are one to two weeks.