Fillers

About Fillers

Fillers are essential decorating and repair products designed to fill cracks, holes, gaps and imperfections in walls, ceilings, woodwork and other surfaces before painting or finishing. Whether you're preparing walls for decoration, repairing damage from removed fixtures, or filling gaps around coving and skirting boards, the right filler ensures a smooth, professional finish that's ready to paint over. From quick-drying formulas for small repairs to deep-gap fillers for larger voids, modern fillers offer solutions for virtually every surface preparation challenge faced by tradespeople and DIY enthusiasts.

Our comprehensive range includes powder fillers that you mix to your preferred consistency, ready-mixed tubs for convenience, flexible fillers that accommodate movement in joints, and specialist products like fine surface fillers for achieving ultra-smooth finishes. Leading brands such as Polycell, Everbuild, Ronseal and Tetrion each offer distinct formulations designed for specific applications, from general-purpose interior repairs to exterior-grade products that withstand weathering. Understanding which type of filler suits your project ensures durability, ease of application and a flawless final appearance.

Modern filler technology has advanced considerably, with innovations like one-strike fillers that require minimal sanding, instant fillers in convenient tubes, and specialised coving adhesives that both fix and fill in a single application. Whether you're a professional decorator working on multiple properties, a builder making good after first-fix work, or a homeowner tackling weekend DIY projects, having the right filler to hand saves time and delivers superior results that stand the test of time.

Jargon Buster

Ready-Mixed Filler

Pre-mixed filler in tubs that's ready to use straight from the container without requiring water or mixing. Ideal for convenience and consistent results, though typically more expensive per application than powder variants.

Powder Filler

Dry filler compound that requires mixing with water to create a workable paste. Economical for larger jobs and offers longer shelf life when stored correctly. Allows you to adjust consistency for different applications.

Flexible Filler

Specialist filler containing elastomeric compounds that remain slightly flexible when cured, preventing cracking in areas subject to movement such as joints between different materials or around door frames.

Deep-Gap Filler

High-build filler formulated to fill deeper holes and larger voids without slumping or excessive shrinkage. Can typically be applied in layers up to 50mm deep without cracking as it dries.

Fine Surface Filler

Smooth, fine-textured filler designed for achieving perfect finishes on walls and ceilings before painting. Sands easily to a ultra-smooth surface and is ideal for filling hairline cracks and minor imperfections.

One-Strike Filler

Advanced formulation that dries quickly and requires minimal or no sanding, allowing decorators to fill, smooth and paint in significantly reduced time compared to traditional fillers.

Who Uses Fillers?

• Painters and decorators preparing surfaces for painting and wallpapering
• Plasterers making good after plastering work and filling minor defects
• Builders and general contractors conducting repairs and making good on construction projects
• Carpenters and joiners filling nail holes, gaps and joints in woodwork
• Property maintenance professionals undertaking repairs across housing stock and commercial buildings
• Electricians and plumbers making good walls and ceilings after installation work
• Shop fitters and dry lining specialists finishing plasterboard installations
• DIY enthusiasts and homeowners conducting household repairs and decorating projects
• Property landlords and letting agents maintaining rental properties between tenancies

How to Choose the Right Fillers

Application Type: Consider whether you need interior or exterior filler, as exterior-grade products contain weather-resistant compounds that prevent water ingress and cracking through temperature changes. Interior fillers prioritise smooth finishing and ease of sanding.

Hole Size and Depth: Match the filler to the repair size. Fine surface fillers work best for hairline cracks and small imperfections, general-purpose fillers handle holes up to about 20mm deep, whilst deep-gap fillers accommodate substantial voids without excessive shrinkage. For very deep holes, apply filler in layers.

Drying Time: Quick-drying and instant fillers allow same-day decoration, essential for time-sensitive projects or professional decorators working to tight schedules. Standard fillers may require 2-4 hours drying time, whilst deep-gap products might need overnight curing.

Flexibility Requirements: Areas subject to movement—such as joints between timber and masonry, around door frames, or along coving—require flexible fillers that won't crack. Rigid fillers suit stable surfaces like solid walls and ceilings where movement is minimal.

Format Preference: Ready-mixed fillers offer convenience and consistency, ideal for smaller jobs and occasional use. Powder fillers provide economy for larger projects and professional use, with the advantage of adjustable consistency and extended shelf life when stored correctly.

Surface Material: Different substrates require compatible fillers. Wood fillers may contain different binders to those designed for plaster or masonry. Some all-purpose fillers work across multiple substrates, offering versatility for varied repair work.

Brand Reputation: Established brands like Polycell, Everbuild and Ronseal offer proven formulations with consistent quality. Professional-grade products from specialist manufacturers often provide superior adhesion, reduced shrinkage and easier finishing characteristics.

Popular Accessories

• Filling knives and scrapers in various widths for applying filler smoothly
• Sanding blocks and abrasive paper for finishing filled areas to a smooth surface
• Mixing buckets and paddles for preparing powder fillers to consistent texture
• Decorator's caulk for flexible gap-filling around frames and skirting boards
• Mastic guns and applicators for dispensing tube and cartridge fillers
• Paint brushes and rollers for decorating over filled surfaces
• Primer and undercoat to seal filled areas before top coating
• Dust sheets and masking tape to protect surrounding areas during filling work
• Cleaning cloths and water containers for tool cleaning and surface preparation

Safety Information

Most modern fillers are relatively low-hazard products, but proper handling practices ensure safe use. Always work in well-ventilated areas when applying filler, particularly with larger applications or in confined spaces. Some fillers may cause minor skin or eye irritation, so consider wearing protective gloves and safety glasses when undertaking extensive filling work.

When sanding dried filler, particularly in enclosed spaces, dust masks prevent inhalation of fine particulates. This is especially important when removing substantial quantities of material. Follow COSHH guidelines when using fillers in professional settings, and consult product safety data sheets for specific handling requirements.

Store powder fillers in dry conditions to prevent premature setting, and keep ready-mixed products sealed when not in use to maintain workability. Keep all filling products away from children and pets. Dispose of excess filler responsibly—never pour liquid filler down drains as it can cause blockages. Clean tools promptly with water before filler sets hard.

Frequently Asked Questions

How long should I wait before painting over filler?

Drying times vary by product and depth of fill. Quick-drying fillers may be ready to paint within 30-60 minutes, whilst standard fillers typically require 2-4 hours. Deep fills may need 24 hours or longer. Always ensure filler is completely dry (changes from pink to white or dark to light depending on product) and lightly sand before painting for best results.

Why does my filler keep cracking?

Cracking typically occurs when filler is applied too thickly in a single application, particularly in deep holes. Build up deep repairs in layers no more than 10-20mm thick, allowing each to dry before applying the next. Cracking may also indicate you need flexible filler for areas subject to movement, or that the substrate wasn't properly prepared.

Can I use interior filler outside?

Interior fillers aren't formulated to withstand weathering and will deteriorate when exposed to rain, frost and UV light. Always use exterior-grade filler for outside applications—these contain weather-resistant additives and flexible compounds that accommodate temperature-related expansion and contraction without cracking.

What's the difference between filler and decorator's caulk?

Filler is designed to fill holes and cracks in solid surfaces and sets rigid when dry, ideal for repairs that can be sanded smooth. Decorator's caulk remains flexible when cured, making it perfect for sealing gaps between different materials (like skirting boards and walls) where some movement occurs. Caulk typically isn't sandable and is applied with a mastic gun.

How do I achieve a perfectly smooth finish?

Use fine surface filler for best results, applying with a wide filling knife in smooth, even strokes. Slightly overfill the defect, then draw the knife across to level it flush with the surrounding surface. Once dry, sand with fine-grit abrasive paper (180-240 grit) using light, circular motions. Wipe away dust and prime before painting for a flawless finish.