The Complete Guide to Wall and Wood Repair: Fillers, Putty & Patching with Selleys Products product guide

AI Summary

Product: Selleys Wall and Wood Repair Range (Spakfilla Rapid, Spakfilla Heavy Duty, No More Cracks, No More Gaps, Plastic Wood, Plasti-Bond Heavy Duty) Brand: Selleys Australia Category: Wall fillers, wood fillers, gap sealants, and structural repair putties Primary Use: Filling, patching, and sealing cracks, holes, voids, and movement joints in walls, plasterboard, timber trim, and exterior timber surfaces across Australian residential applications.

Quick Facts

• Best For: Australian homeowners tackling interior and exterior wall, plasterboard, timber trim, and exterior timber repair before painting or staining
• Key Benefit: A matched product range covering every repair scenario — rigid fillers for stable surfaces, flexible sealants for movement joints, and structural putty for deep voids — which eliminates the single most common cause of repair failure: choosing the wrong product
• Form Factor: Range includes ready-mixed tubs (Spakfilla Rapid, Spakfilla Heavy Duty), cartridge/tube sealant (No More Gaps), powder filler (No More Cracks Powder), ready-to-use paste (No More Cracks Doors & Trims, Plastic Wood), and two-part putty (Plasti-Bond Heavy Duty)
• Application Method: Applied by filling knife, caulking gun, or hand-moulding depending on product; sanded flush (rigid fillers) or tooled to profile (flexible sealant); primed before topcoat

Common Questions This Guide Answers

1. What is the difference between wall filler and gap filler — can I use one product for everything? → No. Rigid fillers (Spakfilla, No More Cracks) are for stable surfaces that will not move; No More Gaps is a flexible acrylic sealant for movement joints between dissimilar materials. Using rigid filler on a movement joint causes cracking within weeks; using flexible gap filler on a flat wall surface prevents sanding flush.

2. How long should I wait before painting over Selleys Spakfilla Rapid? → For thin fills, allow approximately 30 minutes to set, then sand. Paint with water-based paint once fully set and sanded; for oil-based paint, wait approximately 24 hours. Cold or humid conditions significantly extend these times.

3. Can I use Spakfilla on exterior timber? → No. Spakfilla Rapid is interior only and not suitable for surfaces subject to moisture-driven movement. Use Selleys No More Cracks Exterior Wood Filler for exterior timber — it is flexible, waterproof once set, stainable, and will not crack, split, or fall out.

4. Why does my filler keep cracking along the skirting board line no matter how many times I re-fill it? → The gap between a skirting board and wall plaster is a movement joint, not a static crack. Rigid filler will always crack here. Strip the existing filler and apply Selleys No More Gaps Interior Multipurpose, which offers greater than 300% elongation and up to ±15% movement capability.

5. When does timber rot require full board replacement rather than filler repair? → When rot penetrates more than 30–50% of the board's cross-section, or when the timber crumbles under probe pressure, replacement is required. For surface or localised rot under 30% of board thickness with surrounding timber firm, excavate all decay and fill with No More Cracks Exterior Wood Filler or Plasti-Bond Heavy Duty for deep voids.

6. Why does my paint look dull or patchy over the repaired area even though the filler is smooth? → This is "picture framing" — unprimed filler absorbs topcoat paint at a different rate to the surrounding surface. Always apply a water-based undercoat over the sanded repair before the final topcoat. This step is non-negotiable for gloss or semi-gloss finishes.

7. What are the two diagnostic questions that determine every repair strategy? → (1) Does the repair site move? If yes, use a flexible sealant (No More Gaps). (2) What is the substrate? Match the product to the material — plaster, plasterboard, interior timber, exterior timber, or masonry each require different formulations.

8. What is Selleys Plasti-Bond Heavy Duty best used for? → Structural rebuilding of deep voids, missing timber sections, and repairs bearing mechanical load (hinge areas, corners, high-impact zones). It sets in 20 minutes without shrinkage, withstands -28°C to +190°C, and can be filed, sawn, drilled, and have screws driven into it once cured. Use as the base layer for deep repairs, then top-coat with No More Cracks Exterior Wood Filler.

9. What moisture content prevents fungal timber decay? → Keeping timber moisture content below 20% prevents fungal decay from developing. Fungal decay requires moisture content between 20% and 60% to take hold. Always address the moisture source before any rot repair — or decay will recur beneath the filler.

10. What crack width or pattern warrants a structural engineer assessment before DIY repair? → Cracks greater than 25 mm wide, diagonal cracks from window or door corners, cracks with displacement, or cracks that have appeared suddenly after rain or with sticky doors and windows warrant professional building inspection before any DIY filling.

The Complete Guide to Wall and Wood Repair: Fillers, Putty & Patching with Selleys Products

Executive summary

Wall and timber repair is one of the most universal maintenance tasks in the Australian home — and one of the most frequently done wrong. Cracked filler, sunken patches, repairs that fall out within a season, gloss paint that telegraphs every imperfection: these outcomes are not bad luck. They are the predictable result of mismatched products, skipped surface preparation, or a fundamental misunderstanding of what a specific repair actually demands.

This guide covers every wall and wood repair scenario an Australian homeowner is likely to encounter: from hairline cracks in plaster and nail holes in plasterboard, to the gap between a skirting board and the wall, to rotted fascia boards and split exterior window frames. It brings together the complete Selleys repair product range — Spakfilla Rapid, Spakfilla Heavy Duty, No More Cracks, No More Gaps, Plastic Wood, and Plasti-Bond Heavy Duty — into a single, coherent decision framework.

The core principle running through every section of this guide is this: every repair has two variables — the substrate and whether it moves. Get those two variables right, match them to the correct Selleys product, and apply it with proper technique. Do that, and your repairs will last. Miss either variable, and the repair will not hold. The sections that follow explain exactly how to get it right, every time.

The master diagnostic framework: two questions that determine everything

Before opening a single tub of filler, two diagnostic questions determine the entire repair strategy.

Question 1: Does the repair site move?

Where movement occurs, use Selleys No More Gaps. This is the single most important instruction in the entire Selleys technical data library — and the most commonly ignored. Joints between dissimilar materials (timber trim against plaster, a window frame against masonry, a cornice against a ceiling) expand and contract with temperature and humidity. A rigid filler applied here will crack and fall out, sometimes within weeks.

Question 2: What is the substrate?

Wall plaster, plasterboard, masonry, interior timber, and exterior timber each have fundamentally different porosity, movement characteristics, and finish requirements. Rigid fillers are developed to close gaps and cover holes and cracks in surfaces that aren't expected to move or flex. The moment that condition — "not expected to move" — is violated, the product category must change.

Cracks form for several reasons: structural settling, thermal expansion and contraction, moisture fluctuations, and poor construction practices. Understanding which of these forces is acting on your specific repair site is what separates a permanent repair from a temporary one.

This two-question framework — substrate type + movement status — is the spine of every product decision in this guide. All five Selleys product families map directly onto the matrix it creates.

Understanding the Selleys repair product ecosystem

The Selleys range is not a collection of interchangeable products in different packaging. Each product family is engineered for a distinct repair scenario. Choosing between them requires understanding the technical differences — not just the label descriptions.

Rigid fillers: for stable surfaces that will not move

With more than a dozen formulations, finding the right rigid filler is straightforward with Selleys — developed to close gaps and cover holes and cracks in a multitude of surfaces that aren't expected to move or flex.

Selleys Spakfilla Rapid is the everyday workhorse for interior pre-paint repairs. It is a ready-mixed lightweight filler that needs just one application — fast drying, virtually non-shrinking, non-cracking, and ideal for filling cracks and holes on surfaces where no structural movement occurs. Its key practical advantage is speed: once set (30 minutes for thin fills), it can be lightly sanded for a smooth finish. After sanding, paint with water-based paints; for oil-based, wait approximately 24 hours.

Selleys Spakfilla Heavy Duty extends the Spakfilla range to tougher conditions. It is a multi-purpose, tough and durable, light grey ready-mixed filler for filling holes, dents, cracks or chips in interior and exterior applications where no structural movement occurs. It works on plaster, brick, concrete, wood, masonry, stone, and primed metal surfaces. Its water and weather resistance makes it the right choice when Spakfilla Rapid's interior-focused formulation is not appropriate.

Selleys No More Cracks is a family of fillers that extends beyond Spakfilla's scope. No More Cracks Powder Fillers are ideal when you need a little more than Spakfilla — the Interior version suits plaster, plasterboard, bricks, and wood that isn't exposed to the elements. The range includes timber-specific formulations worth understanding separately: No More Cracks Interior Wood Filler (stainable, paintable, excellent adhesion, suitable for all interior timber), No More Cracks Exterior Wood Filler (weather-resistant, flexible, stainable, paintable, suitable for all exterior timber), and No More Cracks Doors & Trims — a ready-to-use filler that works inside or outside with gloss paints on doors, windows, architraves, trims, and skirting boards.

Flexible gap filler: for movement joints

No More Gaps is a durable, flexible acrylic gap sealant for interior and exterior applications where joint movement causes rigid fillers to crack or fall out. It offers superior flexibility to cope with building movement, with greater than 300% elongation and up to ±15% movement capability, which means gaps stay hidden for longer.

This is not a filler in the traditional sense — it is a flexible acrylic sealant. Its job is to seal joints that move, not to fill voids that will be sanded flush. Selleys No More Gaps Interior Multipurpose is designed for gaps and cracks around skirting boards, cornices, and inside window and door frames, with a water-based formulation built to cope with building movement for a long-lasting, crack-resistant finish.

Structural repair putty: for heavy-duty rebuilding

When you need to mould the filler, Selleys Plasti-Bond Heavy Duty is a plastic putty that can be shaped before it hardens. This two-part compound sets in 20 minutes without shrinkage, withstands temperatures between -28°C and +190°C, and once cured can be filed, sawn, sanded, planed, drilled, tapped, nailed, painted, and have screws driven into it. It is the structural rebuilding compound in the Selleys range — used as the base of deep voids before a finishing filler coat is applied.

Quick-reference product selector

No More Gaps cures to a flexible, paintable film — it cannot be sanded flush like a rigid filler.

(For a complete product decision walkthrough, see our detailed guide: Wall Filler vs. Wood Filler vs. Gap Filler: Which Selleys Product Do You Actually Need?)

How to fill cracks and holes in walls and plasterboard

Diagnosing the crack before reaching for any product

The most important decision in any wall repair is made before any product is opened: is this crack cosmetic or structural?

Cosmetic cracks are hairline, shallow, and often random. Structural concerns show patterns and context — long diagonals from openings, stepped cracks along joints, widening gaps, damp stains, or new lines appearing after rain. Sticky doors or windows add further risk. In those cases, pause the DIY work and get a professional assessment before you fix wall cracks.

Surface fillers grip the outermost layer of the wall, but they rarely address whatever caused the damage in the first place. A hairline crack from seasonal timber expansion, for instance, will open again as soon as temperatures change — the filler fractures, the paint breaks apart, and you face the same problem a second time.

For crack sizing, use this decision table:

Surface preparation: the step that determines whether repairs last

Successful repair depends on adhesion, and adhesion depends on preparation — dust, laitance, or residue kills adhesion before it starts. Crack fillers rely on proper bonding with the substrate; if the surface is not prepared correctly, adhesion breakdown is inevitable.

The correct preparation sequence:

1. Remove all loose, flaking, or crumbling material from the repair zone
2. Widen the crack slightly with a utility knife to create a clean edge and give the filler a mechanical key to grip
3. Brush or vacuum out all dust — do not simply wipe with a dry cloth
4. Dry the surface completely, as moisture interferes with the filler and causes adhesion issues
5. If the surrounding paint is glossy, sand with 120-grit paper to create a mechanical bond

The layering rule: why single-pass deep fills always fall short

Apply filler in thin layers rather than one thick application — overfilling leads to shrinkage and cracking. Use a filling knife to push the filler into the crack, then smooth over. For deeper cracks, allow each layer to dry before adding more.

For Spakfilla Heavy Duty on repairs deeper than 6 mm, apply in 6 mm layers, allowing each to dry fully (2–3 hours at room temperature) before applying the next. This is not optional. The mechanism is straightforward: water-based fillers cure by evaporation. When applied too thickly, the outer surface skins and hardens while the inner mass remains wet — internal stresses form as the interior continues to shrink, and the result is cracking that propagates up through primer and topcoat.

Feathering: the technique that makes repairs invisible

Always feather the edges out beyond the crack by 50 to 100 mm — this avoids visible ridges after painting. Feathering means applying each successive coat with a progressively wider knife, tapering the edges far out onto the existing wall. It is the single most important skill in achieving a seamless wall repair, and the step most often skipped.

Large holes: when you need backing support

For holes greater than 25 mm wide in plasterboard, filler alone cannot bridge the void — there is no solid substrate behind the hole to support it. The Selleys Spakfilla Wall Repair Kit provides an adhesive mesh patch that creates the structural backing. Apply the mesh over the hole, press firmly, then apply Spakfilla Rapid from the kit over the mesh in a thin first coat, forcing it into the mesh weave. Allow to dry, then apply a second coat, feathering the edges out onto the surrounding wall.

(For the complete step-by-step workflow on every hole and crack size, see our detailed guide: How to Fill Cracks and Holes in Walls and Plasterboard: A Step-by-Step Selleys Guide)

How to repair skirting boards, architraves, and timber trim

Why trim repair is always a two-product job

Skirting boards, door architraves, and window trims present a repair scenario fundamentally different from patching a wall. These timber elements sit at a junction between two dissimilar materials — timber and plaster or masonry — each of which moves at a different rate in response to temperature and humidity.

Every piece of timber trim has two distinct repair zones, each requiring a different product:

Confusing these zones is the single most common cause of disappointing trim repair results. Applying a rigid filler to Zone 1 and a flexible gap filler to Zone 2 will both produce repairs that do not hold — for opposite reasons.

Zone 1: sealing the wall-timber junction with No More Gaps

The gap between a skirting board and the wall plaster is a movement joint, not a static crack. No More Gaps offers superior flexibility to cope with building movement, with greater than 300% elongation and up to ±15% movement capability, which keeps gaps hidden for longer.

No More Gaps can be painted over with both water and oil-based paints after the surface has skinned, approximately 30 minutes after application. Full cure takes within 24 hours.

Application technique for the wall-timber junction:

1. Remove any old, cracked filler using a scraper or utility knife
2. Apply masking tape to both sides of the gap
3. Run a continuous bead of No More Gaps along the full length of the junction
4. Tool the bead with a wet finger in one smooth pass to create a concave profile
5. Pull masking tape at a 45-degree angle before the filler skins over
6. Allow 30 minutes skin time before painting

Zone 2: repairing the timber face for gloss paint

The timber face requires the opposite of Zone 1: a filler that sets hard, sands flush, and holds up under gloss paint without telegraphing through. Selleys No More Cracks Doors & Trims is a ready-to-use filler that works inside or outside with gloss paints on doors, windows, architraves, trims, and skirting boards.

For a nail hole or small dent, a single pass with the blade at approximately 30 degrees to the surface will pack the filler in and wipe the excess clean in one motion. For chips or gouges deeper than 2 mm, slightly overfill the repair to account for minor shrinkage during drying. Apply in layers no deeper than 6 mm, allowing each to dry before the next.

The primer coat is non-negotiable for gloss finishes. An unprimed filler patch will absorb the topcoat unevenly, leaving a visible "halo" of dull paint around the repair — sometimes called "picture framing." Always apply a water-based undercoat after sanding, before the gloss topcoat.

(For the complete two-zone workflow including the two-coat fill, two-sand finishing method for gloss paint, see our detailed guide: How to Repair and Fill Skirting Boards, Architraves, and Timber Trim Before Painting)

How to repair rotted, damaged, or split exterior timber

Why exterior timber repair is in a category of its own

Exterior timber repair is the most technically demanding scenario in this series. Wood rot is arguably the number one enemy of timber homes across Australia — it is not just an aesthetic issue; it is a living biological process where fungi consume the wood fibres, compromising the integrity of everything from window sills and fascia to structural deck supports. Since timber is an enduring feature of many Australian home styles, knowing how to identify, stop, and repair wood rot is essential for protecting your property.

The science of timber rot: why prevention matters as much as repair

Fungal decay is caused by a biological attack within the wood by certain species of fungi — the fungus can lie dormant in the timber for years until the right conditions present themselves. Those conditions are oxygen, moisture, and nutrients, with moisture being the critical component. If moisture is not present in timber, the fungi will remain dormant, even when oxygen and nutrients are abundant.

Three types of fungi destroy wood: brown, white, and soft rot. Fungi spores are in the air but only take root and cause decay if the moisture content of timber is more than 20% and less than 60%. The practical implication: keep moisture content below 20% and fungal decay will not develop.

Generally, decay of floorboards is caused by brown rot fungi, decay of window joinery by either brown rot or white rot fungi, and decay of weatherboards by white rot (though sometimes brown rot). A species of Coniophora causing brown rot is believed to be the most common form of timber decay fungus in Australia, likely because of high external temperatures.

Decay fungi enzymatically degrade complex cellulosic materials such as wood into simple digestible products — the decay of wood cells results in loss of weight and strength. This is why an exterior timber repair is never purely cosmetic: it is a structural and weatherproofing task.

Assessing damage severity: fill or replace?

The probe test: Use a screwdriver or awl to probe suspect timber. Firm resistance indicates sound wood. If the tool penetrates easily, or the timber crumbles or feels spongy, the decay extends beyond the surface.

Choosing the right Selleys product for exterior timber

Selleys No More Cracks Exterior Wood Filler is the primary exterior timber filler for the vast majority of residential repair scenarios. It is a weather-resistant flexible filler that flexes with wood movement, will not crack, split, or fall out, is stainable and paintable, has excellent adhesion, can be nailed or planed, and is waterproof once set. Apply in 10 mm layers for deeper repairs.

Selleys Plasti-Bond Heavy Duty is the structural rebuilding compound for deep voids or repairs that must bear mechanical load — hinge areas, corner sections, high-impact zones. It sets in 20 minutes without shrinkage. The proven workflow: use Plasti-Bond as the base of deep repairs, filling to approximately 5–10 mm below the final surface level, then top-coat with No More Cracks Exterior Wood Filler for the finishing layer.

The non-negotiable first step: remove all rotten material

Covering a water stain without first locating and fixing the source traps dampness behind the repaired surface — over months, that concealed moisture softens plasterboard, encourages mould to establish, and causes the surrounding area to break down further. The same principle applies with even greater force to exterior timber rot: applying filler over rotten wood traps moisture and fungal material, guaranteeing re-decay beneath the repair.

Rot requires sustained moisture. By eliminating the water source and applying the correct repair methods, you can stop the decay and restore the strength of the affected timber.

Use a chisel, screwdriver, or oscillating multi-tool to excavate all soft, spongy, or discoloured timber. Work back to firm, sound wood — even if this means removing more material than initially planned. Allow the timber to dry completely before applying any filler.

(For the complete step-by-step exterior timber repair workflow including Plasti-Bond mixing ratios and layered application technique, see our detailed guide: How to Repair Rotted, Damaged, or Split Exterior Timber with Selleys Wood Fillers)

Why repairs fall short: the seven root causes — and how to prevent every one

Understanding why repairs fail is as important as knowing how to execute them correctly. Most issues arise from improper surface preparation, incorrect product selection, or ignoring crack behaviour. Here is the complete diagnostic framework.

Root cause 1: wrong product for the substrate or movement status

The symptom is a repair that looks fine initially, then cracks, crumbles, or detaches within weeks or months. Not all cracks are the same — some are static, while others are dynamic and continue to move. The governing rule: if the two surfaces on either side of a gap can move independently of each other, you need a flexible product, not a rigid filler. No More Gaps is a durable, flexible acrylic gap sealant for interior and exterior applications where joint movement causes rigid fillers to crack or fall out.

Root cause 2: insufficient surface preparation

The symptom is filler that lifts cleanly away from the surface — sometimes in a single piece — days or weeks after application. Successful repair depends on adhesion, and adhesion depends on preparation — dust, laitance, or residue kills adhesion before it starts. Clean the crack using compressed air or vacuum after mechanical scraping, and dry the area thoroughly. Most repair materials will not bond to damp surfaces unless rated for moisture tolerance.

Root cause 3: overfilling in a single coat

The symptom is a repair that sinks below the surface level as it dries, or cracks across the surface skin. Applying too much filler in one pass affects performance — apply in controlled layers based on crack width and depth. For deeper cracks, apply in 6 mm layers, allowing each layer to dry before applying the next.

Root cause 4: painting before the filler has fully cured

The symptom is paint that bubbles, wrinkles, or cracks over the repair days or weeks after painting. Always check that the filler has fully hardened and lightened in colour before painting — applying paint too early can cause flashing, peeling, or poor adhesion.

Cold or humid conditions significantly extend cure times beyond the standard 30-minute guideline.

Root cause 5: rigid filler across a movement joint

The symptom is a crack that reappears along the same line repeatedly, no matter how many times it is re-filled. No More Gaps offers superior flexibility to cope with building movement, with greater than 300% elongation and up to ±15% movement capability. That level of elasticity means the sealant stretches and recovers with the joint rather than cracking under stress.

Root cause 6: poor adhesion on glossy or sealed surfaces

The symptom is filler that peels away from the edges of the repair, or paint that lifts in sheets over the repair. Filler relies on mechanical adhesion — microscopic penetration into a porous surface. A glossy, sealed, or heavily painted surface has almost no porosity, and residue from oil or sealer will compromise adhesion and shorten repair life.

The fix: sand the repair area with 80–120 grit sandpaper to break through the gloss layer and create a mechanical key before applying any filler.

Root cause 7: skipping the primer coat before painting

Unprimed filler absorbs topcoat paint unevenly, leaving a visible dull patch around the repair that becomes dramatically more obvious under gloss or semi-gloss finishes. This "picture framing" effect is one of the most common complaints after trim repairs. Always apply a water-based undercoat after sanding and before the final topcoat — this step is non-negotiable for any gloss finish.

(For the complete diagnostic guide to every root cause with product-specific fixes, see our detailed guide: Why Your Filler Keeps Cracking, Shrinking, or Falling Out — and How to Fix It for Good)

Cross-cutting analysis: the unified system behind every successful repair

The five cluster articles in this series each address a distinct repair scenario. Taken together, they reveal a consistent set of principles that apply across all of them — insights that no individual article can provide alone.

Principle 1: the rigid-flexible boundary is the master rule

Whether you are patching a nail hole in plasterboard, filling a skirting board gap, or rebuilding a rotted fascia board, the same master rule governs product selection: rigid fillers for stable surfaces, flexible sealants for movement joints. This principle appears in every cluster article because it is the rule most often overlooked in every common repair scenario. The wall-to-skirting junction, the cornice-to-ceiling junction, the window frame-to-masonry junction — these are all movement joints. They will always produce a poor result with rigid filler, regardless of brand, application technique, or number of coats.

Principle 2: surface preparation matters more than product quality

The optimal properties of repair materials include excellent consistency, minimal shrinkage, strong adhesion to the substrate, high cohesive strength, low liquid water absorption, and colour and texture equivalence to the substrate. But even the most technically advanced filler cannot compensate for a contaminated, damp, or glossy substrate. The cluster articles on wall repair, trim repair, and exterior timber repair all converge on the same finding: the majority of repair shortcomings trace back to surface preparation, not product quality.

Principle 3: depth of repair determines application strategy

Across all repair scenarios — walls, trim, exterior timber — the layering rule is universal. Flexible fillers accommodate small surface movements such as expansion and contraction, adjusting to temperature changes and pressure fluctuations without cracking or losing adhesion. For rigid fillers, the equivalent principle is layer depth: no single application deeper than 6–10 mm (depending on product), with full drying between coats. Overlook this rule on a nail hole and the consequence is minor. Overlook it on a deep timber void and the repair will not hold structurally.

Principle 4: exterior repairs require a fundamentally different product tier

Interior fillers — including standard Spakfilla — are not engineered for the moisture cycling, UV exposure, and temperature extremes of Australian exteriors. Most wood-rotting fungi thrive at temperatures between 20–30°C — wet rot fungi typically occur in persistently damp conditions needing an optimum moisture content of 50–60%, while dry rot grows best at just 30–40%. A filler that cannot flex with moisture-driven timber movement will delaminate and allow water re-entry, recreating the exact conditions that caused the rot in the first place.

Principle 5: the finish coat amplifies every imperfection

Gloss paint is the most demanding topcoat in residential use — it reflects light directly, making every surface irregularity visible. This is why the finishing protocol for timber trim (two-coat fill, two-sand, prime, gloss) is more demanding than the protocol for flat-painted walls. Product selection, layering technique, feathering, priming, and topcoat choice form a system. Getting one element right while neglecting another produces a visible result that falls short of professional standard.

Frequently asked questions

Q1: What's the difference between wall filler and gap filler — can't I just use one product for everything?

No — and this is the most consequential misunderstanding in DIY repair. Wall filler (such as Spakfilla) is a rigid compound designed for stable surfaces that will not move. Gap filler (such as No More Gaps) is a flexible acrylic sealant designed for joints between dissimilar materials that expand and contract. A crack seal stays flexible to bridge tiny movements around joints, frames, and mixed materials — a wall crack filler cures firmer and sands smooth for painting. Using rigid filler on a movement joint will result in cracking within weeks; using flexible gap filler on a flat wall surface will result in a repair that cannot be sanded flush.

Q2: How long should I wait before painting over Selleys Spakfilla?

Once set — approximately 30 minutes for thin fills — lightly sand for a smooth finish. After sanding, paint with water-based paints; for oil-based, wait approximately 24 hours. These are minimum times for thin applications under ideal conditions. For fills deeper than 2 mm, or in cold or humid conditions, allow significantly longer. The filler must be fully hardened and uniform in colour before any paint is applied.

Q3: Can I use Spakfilla on exterior timber?

Spakfilla Rapid is not recommended for exterior timber that is likely to swell or shrink through moisture absorption — and because it is not flexible, it is not suitable for surfaces subject to structural movement. For exterior timber, use Selleys No More Cracks Exterior Wood Filler, which is specifically formulated to flex with wood movement, is waterproof once set, and will not crack, split, or fall out.

Q4: My filler keeps cracking along the skirting board line no matter how many times I re-fill it. Why?

This is the classic symptom of a movement joint being treated with a rigid filler. The gap between a skirting board and the wall plaster is not a static crack — it is a joint between two materials that move at different rates. Selleys No More Gaps products are designed to withstand movement, ensuring they remain crack free for longer. Strip out all existing rigid filler from the junction, allow the surface to dry, and apply Selleys No More Gaps Interior Multipurpose. It will flex with the seasonal movement rather than fracturing under it.

Q5: When does timber rot require full replacement rather than filler repair?

The threshold is approximately 30% of the board's cross-section. For small, shallow, or non-structural areas where rot is limited to the surface (less than 30% of the board's thickness), remove the decay and use a specialised filler to restore the wood's shape and integrity. For deep, structural, or widespread rot — where the timber crumbles under probe pressure, or where rot penetrates more than 30–50% of the cross-section — the affected section or entire board must be replaced. Rot requires sustained moisture, so address the moisture source before any repair, or the rot will recur beneath the filler.

Q6: Can No More Gaps be sanded smooth like a rigid filler?

No. Cured No More Gaps caulk will need to be cut away — remaining caulk can be softened with acetone and then removed. Its flexible, rubbery cure prevents it from sanding to a crisp, flush finish — it tears rather than sands. No More Gaps is designed to be tooled to a smooth concave profile at the junction and painted over, not sanded flush with the surrounding surface. For repairs that require sanding flush, use a rigid filler appropriate to the substrate.

Q7: What is Selleys Plasti-Bond Heavy Duty best used for, and when should I choose it over No More Cracks?

Plasti-Bond Heavy Duty is a two-part structural repair putty — not a surface filler. It is best used for rebuilding deep voids, missing sections of timber (such as a corner of a window sill or decking edge), and repairs that must bear mechanical load such as hinge areas or high-impact zones. When you need to mould the filler, Plasti-Bond Heavy Duty is a plastic putty that can be shaped before it hardens. Use it as the base layer for deep voids, then top-coat with No More Cracks Exterior Wood Filler for the final surface layer. No More Cracks Exterior Wood Filler is the right choice for surface cracks, splits, and moderate-depth voids where structural rebuilding is not required.

Q8: Why does my paint look dull or patchy over the repaired area even though the filler is smooth?

This is "picture framing" — the unprimed filler is absorbing the topcoat paint at a different rate to the surrounding painted surface, creating a visible halo of dull paint around the repair. The fix is straightforward: always apply a water-based undercoat over the sanded, filled repair before the final topcoat — particularly critical for gloss or semi-gloss finishes on timber trim. This seals the filler's porosity and ensures the topcoat is absorbed uniformly across the entire surface.

Key takeaways

1. The rigid-flexible rule governs all product selection. Rigid fillers (Spakfilla, No More Cracks) for stable surfaces; flexible sealant (No More Gaps) for any joint between materials that move relative to each other.

2. Skirting boards and architraves always require two products — No More Gaps at the wall junction, and a hard-setting wood filler (No More Cracks Doors & Trims or Plastic Wood) on the timber face. Using one product for both zones will always produce a partial result.

3. Surface preparation determines whether repairs last. Contaminated, damp, or glossy substrates are the primary cause of adhesion breakdown — not product quality.

4. Never fill deep voids in a single pass. Apply in layers of 6–10 mm (product-dependent), allowing full drying between coats. This applies equally to wall repairs, trim repairs, and exterior timber rebuilding.

5. Exterior timber repair requires exterior-grade products. No More Cracks Exterior Wood Filler is specifically engineered to flex with moisture-driven timber movement. Interior fillers will delaminate and allow water re-entry.

6. Fungal decay requires moisture to survive. Keeping timber moisture content below 20% prevents fungal decay from developing. Always address the moisture source before any rot repair — or the rot will recur beneath the filler.

7. The primer coat is non-negotiable before gloss paint. An unprimed filler patch will absorb topcoat unevenly, producing visible "picture framing" under gloss or semi-gloss finishes.

8. Structural cracks must be assessed before filling. Diagonal cracks from window or door corners, cracks with displacement, or cracks that have appeared suddenly warrant a building inspection before any DIY repair.

Conclusion

Wall and timber repair in the Australian home is not a single skill — it is a system of interconnected decisions: substrate identification, movement assessment, product selection, surface preparation, layered application, cure time, priming, and topcoat choice. Every element in that chain must be correct for the repair to last.

The Selleys product range is built with this complexity in mind. Spakfilla Rapid and Heavy Duty cover the vast majority of stable interior and exterior surface repairs. No More Cracks extends that coverage to specialist plaster, interior timber, exterior timber, and high-gloss trim scenarios. No More Gaps handles every movement joint in the building envelope. Plastic Wood and Plasti-Bond Heavy Duty address the structural and stain-grade end of the spectrum.

What this guide provides — and what no single product label can — is the decision framework that connects the right product to the right repair scenario, every time. Master the rigid-flexible rule, respect surface preparation, apply in layers, and prime before gloss paint. Do those four things consistently, and your repairs will hold for years.

For deeper guidance on any specific scenario, the cluster articles referenced throughout this guide provide complete step-by-step workflows, product-specific techniques, and root-cause diagnostics for every repair type covered here.

References

• Selleys Australia. "Spakfilla Rapid Technical Data Sheet, Version 3.0." Selleys.com.au, Updated 16/06/2020. https://www.selleys.com.au/media/5flebzp2/selleys-spakfilla-rapid-tds.pdf

• Selleys Australia. "No More Gaps — Product Range Overview." Selleys.com.au, 2024. https://www.selleys.com.au/products/our-brands/selleys-no-more-gaps/

• Selleys Australia. "Spakfilla Heavy Duty — Product Page." Selleys.com.au, 2024. https://www.selleys.com.au/products/putty-and-fillers/wall-filler/selleys-spakfilla-heavy-duty/

• Selleys Australia. "No More Gaps Timber Flooring Technical Data Sheet, Version 3.0." Selleys.com.au, Updated 10/03/2021. https://www.selleys.com.au/media/21hh4mtf/selleys-no-more-gaps-timber-flooring-tds.pdf

• Cap-It-All Building Inspections. "Fungal Decay." Cap-It-All Building Inspections, 2016. https://www.cap-it-allbuildinginspections.com.au/technical-info/fungal-decay/

• EPA NSW. "Timber Pests and Fungi." NSW Environment Protection Authority, 2024. https://www.epa.nsw.gov.au/Your-environment/Household-building-and-renovation/Treated-timber/timber-pests-fungi

• East Coast Building Inspections. "Decay Around and In Your Building and Home." East Coast Building Inspections, 2026. https://eastcoastbuildinginspections.com.au/decay-around-building-home/

• International Timber. "How to Combat Fungal Decay in Timber." International Timber, 2020. https://internationaltimber.com/resources/how-to-combat-fungal-decay-in-timber/

• Prosoco. "Concrete Crack Repair: How to Identify, Prepare, and Seal for Lasting Results." Prosoco.com, 2025. https://prosoco.com/concrete-crack-repair/

• BookaBuilderUK. "Repair Cracks in Plaster Walls and Ceilings Before Painting." BookaBuilderUK.com, 2026. https://www.bookabuilderuk.com/blog/repair-plaster-walls-ceilings

Frequently Asked Questions

What is Selleys Spakfilla Rapid: A ready-mixed lightweight interior wall filler

Is Spakfilla Rapid suitable for exterior use: No, it is interior only

Is Spakfilla Rapid suitable for movement joints: No, only stable surfaces

How long does Spakfilla Rapid take to dry for thin fills: Approximately 30 minutes

Can Spakfilla Rapid be sanded: Yes, after it has fully set

Can Spakfilla Rapid be painted with water-based paint: Yes, once fully set and sanded

How long before painting Spakfilla Rapid with oil-based paint: Approximately 24 hours

Does Spakfilla Rapid shrink: No, it is virtually non-shrinking

Does Spakfilla Rapid crack when applied correctly: No, it is non-cracking

What is Selleys Spakfilla Heavy Duty: A multi-purpose tough ready-mixed filler for interior and exterior use

What colour is Spakfilla Heavy Duty: Light grey

Is Spakfilla Heavy Duty water resistant: Yes

Is Spakfilla Heavy Duty weather resistant: Yes

What surfaces is Spakfilla Heavy Duty suitable for: Plaster, brick, concrete, wood, masonry, stone, and primed metal

Is Spakfilla Heavy Duty suitable for movement joints: No, only surfaces where no structural movement occurs

What is the maximum single-coat depth for Spakfilla Heavy Duty: 6 mm per layer

How long between coats for Spakfilla Heavy Duty: 2 to 3 hours at room temperature

What is Selleys No More Gaps: A durable flexible acrylic gap sealant

Is No More Gaps rigid or flexible: Flexible

What is the elongation/stretch rating of No More Gaps: Greater than 300%

What movement capability does No More Gaps offer: Up to ±15% movement

Can No More Gaps be sanded flush like a rigid filler: No, it tears rather than sands

How long does No More Gaps take to skin over: Approximately 30 minutes

How long does No More Gaps take to fully cure: Within 24 hours

Can No More Gaps be painted over: Yes, after the surface has skinned

What is No More Gaps best used for: Sealing movement joints between dissimilar materials

Is No More Gaps suitable for skirting board junctions: Yes

Is No More Gaps suitable for cornice junctions: Yes

Is No More Gaps suitable for window and door frame junctions: Yes

What is Selleys No More Cracks Doors and Trims: A ready-to-use filler for doors, windows, architraves, and skirting boards

Is No More Cracks Doors and Trims suitable for use with gloss paint: Yes

Is No More Cracks Doors and Trims for interior or exterior use: Both interior and exterior

Is No More Cracks Interior Wood Filler stainable: Yes

Is No More Cracks Exterior Wood Filler stainable: Yes

Is No More Cracks Exterior Wood Filler flexible: Yes, it flexes with wood movement

Is No More Cracks Exterior Wood Filler waterproof once set: Yes

What is the maximum single-coat depth for No More Cracks Exterior Wood Filler: 10 mm per layer

Can No More Cracks Exterior Wood Filler be nailed or planed: Yes

What is Selleys Plasti-Bond Heavy Duty: A two-part structural repair putty

How long does Plasti-Bond Heavy Duty take to set: 20 minutes

Does Plasti-Bond Heavy Duty shrink when curing: No

What temperature range can Plasti-Bond Heavy Duty withstand: -28°C to +190°C

Can Plasti-Bond Heavy Duty be drilled after curing: Yes

Can Plasti-Bond Heavy Duty be sawn after curing: Yes

Can Plasti-Bond Heavy Duty have screws driven into it: Yes

What is Plasti-Bond Heavy Duty best used for: Deep voids and structural rebuilding

Should Plasti-Bond be used as a finishing layer: No, top-coat with No More Cracks Exterior Wood Filler

What is Selleys Plastic Wood best used for: Stainable interior timber repairs

Is Plastic Wood suitable for exterior use: No, interior only

What are the two diagnostic questions before any repair: Substrate type and whether the surface moves

What happens if rigid filler is applied to a movement joint: It will crack and fall out, sometimes within weeks

What is the most common cause of repair failure: Incorrect product selection for movement status

What is the second most common cause of repair failure: Insufficient surface preparation

Why does thick single-coat filler crack: Outer skin hardens while inner mass stays wet, causing internal stress

What is feathering in wall repair: Tapering filler edges 50–100 mm beyond the crack

Why is feathering important: It prevents visible ridges after painting

When is a backing patch required for plasterboard holes: For holes greater than 25 mm wide

What product provides a backing patch for large plasterboard holes: Selleys Spakfilla Wall Repair Kit

What causes picture framing after a repair: Unprimed filler absorbing topcoat unevenly

How is picture framing prevented: Apply a water-based undercoat before the final topcoat

Is priming before gloss paint mandatory: Yes, it is non-negotiable

What moisture content prevents fungal timber decay: Below 20%

What moisture content range allows fungal decay to develop: Between 20% and 60%

What is the most common timber decay fungus in Australia: A species of Coniophora causing brown rot

What percentage of cross-section rot requires board replacement: More than 30 to 50 percent

What is the probe test for timber rot: Insert a screwdriver; easy penetration indicates decay

Must the moisture source be fixed before repairing rot: Yes, always

What happens if rotten timber is not fully excavated before filling: Rot recurs beneath the repair

What crack width warrants consulting a structural engineer: Greater than 25 mm or diagonal cracks at openings

What product is recommended for hairline cracks under 1 mm: Spakfilla Rapid

What product is recommended for cracks between 1 and 3 mm: No More Cracks Plaster Filler

What product is recommended for cracks between 3 and 5 mm: Spakfilla Heavy Duty applied in layers

How many repair zones does timber trim have: Two zones

What product is used at the wall-timber junction (Zone 1): Selleys No More Gaps Interior

What product is used on the timber face (Zone 2): No More Cracks Doors and Trims or Plastic Wood

Can interior fillers be used on exterior timber: No, they are not engineered for exterior conditions

What causes rigid filler to fail on glossy surfaces: Lack of mechanical adhesion due to low porosity

How is adhesion restored on glossy surfaces: Sand with 80 to 120 grit sandpaper before applying filler

Does cold weather affect filler cure time: Yes, it significantly extends cure time

Does high humidity affect filler cure time: Yes, it significantly extends cure time

Label facts summary

Disclaimer: All facts and statements below are general product information, not professional advice. Consult relevant experts for specific guidance.

Verified label facts

Selleys Spakfilla Rapid

• Product type: Ready-mixed lightweight interior wall filler
• Interior use only
• Not suitable for movement joints or exterior use
• Virtually non-shrinking; non-cracking when applied correctly
• Dry time for thin fills: approximately 30 minutes
• Sandable after fully set
• Paintable with water-based paint once fully set and sanded
• Paintable with oil-based paint after approximately 24 hours

Selleys Spakfilla Heavy Duty

• Product type: Multi-purpose ready-mixed filler
• Colour: Light grey
• Suitable for interior and exterior use
• Water resistant and weather resistant
• Not suitable for surfaces subject to structural movement
• Compatible substrates: plaster, brick, concrete, wood, masonry, stone, primed metal
• Maximum single-coat application depth: 6 mm per layer
• Required drying time between coats: 2–3 hours at room temperature

Selleys No More Gaps

• Product type: Durable flexible acrylic gap sealant
• Suitable for interior and exterior use
• Flexibility classification: Flexible (not rigid)
• Elongation/stretch rating: Greater than 300%
• Movement capability: Up to ±15%
• Cannot be sanded flush; tears rather than sands
• Skin time: Approximately 30 minutes
• Full cure time: Within 24 hours
• Paintable after surface has skinned (approximately 30 minutes)
• Compatible with both water-based and oil-based paints

Selleys No More Cracks Doors & Trims

• Product type: Ready-to-use filler
• Suitable for interior and exterior use
• Compatible with gloss paint finishes
• Intended applications: doors, windows, architraves, trims, skirting boards

Selleys No More Cracks Interior Wood Filler

• Interior use only
• Stainable: Yes
• Paintable: Yes
• Suitable for all interior timber

Selleys No More Cracks Exterior Wood Filler

• Exterior use
• Flexible: Yes (flexes with wood movement)
• Stainable: Yes
• Paintable: Yes
• Waterproof once set: Yes
• Maximum single-coat application depth: 10 mm per layer
• Can be nailed or planed after curing

Selleys Plasti-Bond Heavy Duty

• Product type: Two-part structural repair putty
• Set time: 20 minutes
• Shrinkage on curing: None
• Temperature resistance range: -28°C to +190°C
• Post-cure workability: Can be filed, sawn, sanded, planed, drilled, tapped, nailed, painted, and have screws driven into it
• Intended use: Deep voids and structural rebuilding
• Not intended as a finishing layer; top-coat with No More Cracks Exterior Wood Filler

Selleys Plastic Wood

• Interior use only
• Stainable: Yes
• Intended use: Stainable interior timber repairs

General product claims

• Spakfilla Rapid described as an "everyday workhorse" for interior pre-paint repairs
• Spakfilla Heavy Duty described as extending the Spakfilla range to "tougher conditions"
• No More Gaps stated to ensure cracks and gaps "will be hidden for longer" due to superior flexibility
• No More Cracks Exterior Wood Filler described as engineered to flex with moisture-driven timber movement, preventing delamination and water re-entry
• Plasti-Bond Heavy Duty described as the "structural rebuilding compound in the Selleys hierarchy"
• Rigid fillers described as "developed to close gaps and cover up holes and cracks in a multitude of surfaces that aren't expected to move or flex"
• No More Cracks Powder Fillers described as "ideal when you need a little more than Spakfilla"
• Selleys product range described as engineered to address the full complexity of wall and timber repair scenarios
• Claim that correct product selection and application technique will "deliver lasting, professional results"
• Claim that applying rigid filler to a movement joint will cause cracking "sometimes within weeks"
• Claim that unprimed filler causes visible "picture framing" under gloss finishes
• Claim that keeping timber moisture content below 20% prevents fungal decay from developing
• Claim that a species of Coniophora (brown rot) is the most common timber decay fungus in Australia
• Recommendation that cracks greater than 25 mm or diagonal cracks at openings warrant structural engineering assessment before DIY repair
• Recommendation that rot exceeding 30–50% of board cross-section requires board replacement rather than filler repair
• Statement that surface preparation is the primary cause of repair failure, not product quality