How to Repair Rotted, Damaged, or Split Exterior Timber with Selleys Wood Fillers product guide

AI Summary

Product: Selleys No More Cracks Exterior Wood Filler / Selleys Plasti-Bond Heavy Duty Brand: Selleys Category: Exterior Timber Repair Fillers Primary Use: Repairing rotted, split, cracked, or damaged exterior timber on Australian homes, including fascia boards, window frames, and decking edges.

Quick Facts

• Best For: Homeowners repairing exterior timber affected by rot, splits, weathering, or impact damage
• Key Benefit: Weather-resistant, flexible repair that moves with timber and won't crack, split, or fall out after curing
• Form Factor: Ready-to-use tub (No More Cracks Exterior Wood Filler, 450g); two-part plastic putty requiring hardener activation (Plasti-Bond Heavy Duty)
• Application Method: Press firmly into clean, dry, excavated timber in 10mm layers; use Plasti-Bond Heavy Duty as structural base for deep voids, finish with No More Cracks Exterior Wood Filler

Common Questions This Guide Answers

1. Can I use interior filler for exterior timber repairs? → No — interior fillers including standard Spakfilla will break down within a single wet season in exterior conditions.
2. How deep can I fill in a single application of No More Cracks Exterior Wood Filler? → Maximum 10mm per layer; deep repairs require multiple layers with drying time between each.
3. When can I paint over a repaired exterior timber surface? → After a deep layered repair, allow a minimum of 24 hours before sanding and priming, then apply exterior-grade topcoat after primer dries.

How to repair rotted, damaged, or split exterior timber with Selleys wood fillers

Exterior timber works hard on every Australian home. Fascia boards deflect summer downpours. Window frames expand and contract through temperature swings of 40°C or more between seasons. Decking edges absorb UV, pooling water, and foot traffic all at once. When this timber fails — through rot, splitting, or impact damage — the stakes are fundamentally higher than any interior job.

The most serious effect of decay in timber is the reduction in strength, which can be quite serious even at an early stage. That means an exterior timber repair is never purely cosmetic: it's a structural and weatherproofing task. The filler you choose must be waterproof once cured, mechanically stable enough to be nailed or planed, and capable of surviving the same thermal and humidity cycling that caused the damage in the first place. Generic interior fillers — including standard Spakfilla or interior-grade wood fillers — won't hold up in these conditions, often breaking down within a single wet season.

This guide walks through the complete exterior timber repair process: diagnosing damage severity, removing rotten material safely, selecting the right Selleys product for each scenario, applying filler in layers for deep repairs, and finishing correctly before paint or stain. It's the most technically demanding repair scenario in this series, and getting it right protects one of your home's most valuable assets.

Why exterior timber fails: the science of rot and splitting

Understanding why exterior timber degrades is the first step to repairing it correctly — and preventing recurrence.

Fungal decay: the primary culprit

Timber rot is a type of decay caused by a combination of fungi and moisture from leaking pipes, poor flashings, broken roof tiles, and leaking shower recesses. In Australia's varied climate, the fungal species responsible differ by timber type and location. Decay of window joinery is caused by either brown rot or white rot fungi, while decay of weatherboards is often by white rot but sometimes by brown rot fungi.

A species of Coniophora (causing brown rot) is believed to be the commonest house timber decay fungus in Australia, thriving in conditions created by poor maintenance, failed paint films, and trapped moisture. Decay also renders wood more permeable, so it absorbs water more readily — making the situation progressively worse.

The practical consequence: once rot begins, it accelerates. Dry rot, also known as brown rot decay, sees fungi mainly target the cellulose in the wood's structure in a process called cubical fracture, where the wood shrinks, the colour becomes deep brown, and the timber breaks down into tiny cube-shaped pieces.

Where exterior timber fails first

Window frames, the mitred ends of fascias, the ends of stair treads, the exposed ends of balcony beams, pergolas, handrails, and weatherboards are the most likely positions for decay to appear in exterior joinery.

These aren't random failure points. They share a common characteristic: locations where end grain is exposed, where water pools, or where paint adhesion is mechanically stressed by timber movement. Common culprits include clogged or broken gutters causing water to cascade over the fascia board, and paint or sealant breakdown on horizontal surfaces like window sills or deck ends, allowing water to wick into the end grain.

The moisture-movement cycle that destroys fillers

Designers of wood-frame buildings generally don't need to account for thermal expansion, because thermal expansion is offset by the shrinkage of wood due to increased temperatures and moisture loss. But this same moisture-driven movement is precisely what destroys rigid fillers applied to exterior timber. As timber absorbs moisture, it swells; as it dries, it contracts. A filler that can't flex with this movement will crack, delaminate, and allow water re-entry — recreating the conditions for rot.

This is the fundamental reason why exterior timber repair demands a purpose-specific product. Using the right product from the start is the only way to guarantee lasting results.

Assessing damage severity: when to fill, when to replace

Before reaching for any filler, a clear-eyed damage assessment determines whether repair is viable. Applying filler to structurally compromised timber isn't a repair — it's a cosmetic delay.

The three-category assessment framework

Wood rot repair falls into two distinct categories based on damage severity. For small, shallow, or non-structural areas where rot is limited to the surface (less than 30% of the board's thickness), you remove the decay and use a specialised filler to restore the wood's shape and integrity. For deep, structural, or widespread rot, you cut out the affected section — or the entire board — and replace it with new, appropriately treated wood.

The probe test: Use a screwdriver or awl to probe suspect timber. Firm resistance indicates sound wood. If the tool penetrates easily, or if the timber crumbles or feels spongy, the decay extends beyond the surface. Work outward from the obvious damage to map the true extent of rot before committing to a repair approach.

Choosing the right Selleys product for exterior timber

Two Selleys products cover the full range of exterior timber repair scenarios. Knowing their distinct properties is what separates a repair that lasts from one that needs redoing. (For a complete product-selection framework across all repair scenarios, see our guide on Wall Filler vs. Wood Filler vs. Gap Filler: Which Selleys Product Do You Actually Need?)

Selleys No More Cracks Exterior Wood Filler

This is a weather-resistant flexible filler that flexes with wood movement, won't crack, split or fall out, is stainable and paintable, has excellent adhesion, can be nailed or planed, is easy to sand, requires only water for cleanup, and is suitable for all exterior timber.

Key technical properties:

• Waterproof once set; durable and resistant to temperature and humidity changes
• Minimal shrinkage, making it well-suited to filling large cracks
• Apply in 10mm layers for deeper repairs
• Water-based formula is low in odour and cleans up with water before drying

Best for: Surface cracks, splits, weathering checks, nail holes, and moderate-depth voids in fascias, window frames, weatherboards, and decking edges. This is your go-to exterior timber filler for the vast majority of residential repair scenarios.

Selleys Plasti-Bond Heavy Duty

Selleys Plasti-Bond Heavy Duty is a multi-purpose plastic putty for filling, bonding, or moulding in building and repair work. It sets in 20 minutes without shrinkage after the hardener is mixed in.

Key technical properties:

• Withstands temperatures between -28°C and +190°C, and is unaffected by fresh or salt water, acids, alkalis, or oils
• Can be filed, sawn, sanded, planed, drilled, tapped, nailed, painted, and have screws driven in
• Suitable for repairing cracks, holes, and splits in wood, plaster, brick, concrete, fibre cement, metal, alloys, ceramics, and fibreglass
• Sets in 20 minutes without shrinking or cracking

Best for: Structural rebuilding of deep voids, rebuilding missing sections of timber (such as a corner of a window sill or decking edge), and repairs that must bear mechanical load — hinge areas, locking points, or high-impact zones.

Critical distinction: Plasti-Bond Heavy Duty is a two-part product requiring hardener activation with a working time of approximately 20 minutes. It's not a surface filler — it's a structural rebuilding compound. Use it for the base of deep repairs, then top-coat with No More Cracks Exterior Wood Filler for the final surface layer.

Step-by-step: repairing rotted or damaged exterior timber

Tools and materials checklist

• Selleys No More Cracks Exterior Wood Filler (450g tub)
• Selleys Plasti-Bond Heavy Duty (for deep voids)
• Stiff-bristled brush or wire brush
• Chisel and/or oscillating multi-tool
• 80-grit and 120-grit sandpaper (or sanding block)
• Putty knife and flexible filling knife
• Mineral turps (for Plasti-Bond tool cleanup)
• Exterior-grade primer
• Exterior paint or stain

Step 1: Remove all rotten and compromised timber

This step is non-negotiable. Applying filler over rotten wood traps moisture and fungal material, guaranteeing re-decay beneath the repair.

All active fungal material should be removed together with all rotten wood, and the structural strength of the remaining timber assessed to determine whether reinforcement or renewal is required.

• 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.
• Address splits before filling. For splits, press the timber back together where possible and allow any movement to settle before filling.
• Brush out all loose debris, dust, and wood fibres with a stiff brush.
• Allow the timber to dry completely. Filling over damp timber is one of the most common causes of filler breakdown. (See our guide on Why Your Filler Keeps Cracking, Shrinking, or Falling Out for the full diagnostic on adhesion issues.)

Step 2: Prepare the surface

• Sand the repair area with 80-grit sandpaper to remove any remaining paint, sealant, or weathered surface that would impede adhesion.
• The surface should be clean, dry, and free from paint, grease, or oil.
• For deep voids, consider undercutting the edges of the excavation slightly with a chisel. This creates a mechanical key — a wider internal cavity than surface opening — that locks the filler in place and resists pull-out.
• No priming is needed before applying Selleys No More Cracks Exterior Wood Filler — the product bonds directly to clean, sound timber.

Step 3: For deep repairs — apply Plasti-Bond Heavy Duty as the base layer

For voids deeper than approximately 15–20mm, or where the repair must support mechanical load, start with Plasti-Bond Heavy Duty.

• Add a 2.5cm length of hardener to every 20ml (heaped tablespoon) of Plasti-Bond Heavy Duty. Mix in the hardener by working the product from side to side until uniform colour is achieved.
• In cold weather, or if faster setting time is needed, add more hardener.
• Do not use below 5°C — cold temperatures inhibit proper curing of water-based fillers, and Plasti-Bond's cure time is also affected below this threshold.
• Press the mixed compound firmly into the base of the void, packing it tightly to eliminate air pockets. Fill to approximately 5–10mm below the final surface level, leaving room for the finishing coat.
• It's easier to smooth off most of the excess with a Surform or Dreadnought file before it becomes rock hard (between 20 and 30 minutes).
• Allow Plasti-Bond to reach full hardness (approximately 30 minutes) before applying the finishing layer.

Step 4: Apply Selleys No More Cracks Exterior Wood Filler in layers

• Press filler firmly into the surface and remove excess. Apply in 10mm layers for deeper repairs — don't attempt to fill a deep void in a single application, as incomplete drying will undermine the result.
• For the first layer, work the filler firmly into the void with a putty knife, pressing it into all edges and corners to eliminate voids.
• Scrape off excess flush with the surrounding surface. A slight overfill of 1–2mm is fine to allow for sanding.
• Allow each layer to dry before applying the next. In warm, dry conditions, surface layers may be ready in 2–3 hours; in humid or cool conditions, allow longer.
• Repeat the layering process until the repair is built up to the surface level of the surrounding timber.

Step 5: Sand, prime, and finish

• Once fully cured, sand the repair starting with 80-grit to remove any high spots, then progress to 120-grit for a smooth finish.
• Apply a coat of exterior-grade primer before painting. While the filler doesn't require priming before application, priming the cured filler before your topcoat significantly improves paint adhesion and longevity — particularly on horizontal surfaces exposed to UV and rain.
• The filler can be stained, painted, tinted, or varnished once fully cured. If staining, note that the filler will accept stain but may absorb it differently than the surrounding timber — test on an inconspicuous area first.
• Protect from rain until painted. The filler is weather-resistant once cured and painted, but the uncured product shouldn't be exposed to rain.

Layering technique for deep exterior repairs: a visual reference

Specific repair scenarios: fascia boards, window frames, and decking edges

Rotted fascia boards

Fascia boards sit directly below the roof line and face chronic exposure to gutter overflow, driving rain, and sun. The mitred ends are the most vulnerable — end grain absorbs water like a wick.

After excavating rot and drying the timber, use Plasti-Bond Heavy Duty to rebuild any missing corner sections (mould the compound against a piece of tape or card held flush with the board face). Once hardened, fair back with No More Cracks Exterior Wood Filler, sand, and prime all exposed end grain aggressively before topcoating. Coating all cut ends with an end-grain preservative or a thick coat of oil-based primer is the single most important step against future rot — end grain acts like a sponge for water.

Split window frames

Window frames face constant thermal and moisture cycling, and splits typically run with the grain. Before filling, stabilise the split: if the timber has separated, apply exterior-grade wood glue into the split, clamp, and allow to cure fully before any filling. Then apply No More Cracks Exterior Wood Filler, pressing firmly into the split to fill the full depth. The filler's flexibility accommodates residual movement without cracking.

Damaged decking edges

Decking edges — particularly at board ends and around fixings — are prone to splitting, impact damage, and rot from standing water. Decks should be cleaned and resealed annually, with checks for pooling water. For localised edge damage, No More Cracks Exterior Wood Filler is the right product. For missing or severely degraded sections where the board edge has broken away, rebuild the profile with Plasti-Bond Heavy Duty, then finish with No More Cracks Exterior Wood Filler to achieve a smooth, paintable surface.

Cure times and finishing: getting the timing right

One of the most common reasons exterior repairs break down prematurely is painting or staining before the filler has fully cured. The product may feel dry to the touch on the surface while moisture is still releasing from deeper layers — particularly in layered applications or humid conditions.

General cure time guidelines for Selleys No More Cracks Exterior Wood Filler:

• Surface dry: 1–2 hours (warm, low-humidity conditions)
• Through-dry (single layer): 2–4 hours
• Through-dry (deep layered repair): Allow 24 hours minimum before final sanding and priming
• Ready for topcoat: After primer has dried per primer manufacturer's instructions

For Plasti-Bond Heavy Duty:

• After 30 minutes it can be painted, or coloured with paint tinter or cement oxide powder
• Full mechanical hardness (for filing, sanding, drilling): approximately 30 minutes after mixing

Temperature considerations: Do not use below 5°C. At low temperatures, water-based fillers cure slowly and incompletely, resulting in weak repairs. In summer conditions above 35°C, work in shade to prevent the surface skinning before the filler is fully pressed into the repair.

Long-term maintenance: protecting your repair investment

A correctly executed filler repair restores form and weather-resistance — but ongoing maintenance is what keeps it performing year after year.

Apply protective stains to fences every 2–3 years, clean and reseal decks annually while checking for pooling water, and inspect joints and posts in outdoor structures for signs of damp.

Beyond scheduled maintenance, address the source of the moisture that caused the original damage:

• Clear and repair gutters and downpipes to prevent overflow onto fascias
• Ensure window flashings are intact and sealed
• Improve drainage around deck perimeters to prevent pooling
• The number one rule in preventing wood from rotting is to control moisture

For skirting boards, architraves, and interior timber trim that also require repair before painting, the workflow and product selection differ significantly from exterior applications — see our guide on How to Repair and Fill Skirting Boards, Architraves, and Timber Trim Before Painting for the complete interior timber repair process.

Key takeaways

• Exterior timber repair demands purpose-specific products. Selleys No More Cracks Exterior Wood Filler is a ready-to-use weather-resistant flexible filler that moves with the wood and won't crack, split, or fall out. Interior fillers won't hold up in these conditions.
• Remove all rotten material before filling. Filling over compromised timber traps moisture and fungal matter, guaranteeing re-decay. Work back to firm, sound wood regardless of how much material must be removed.
• Layer deep repairs — never fill a void in a single pass. Apply in 10mm layers. For structural voids, use Plasti-Bond Heavy Duty as the base layer before finishing with No More Cracks Exterior Wood Filler.
• Cure time matters more outdoors than indoors. Allow deep, layered repairs at least 24 hours before final sanding and priming. Painting over incompletely cured filler is a primary cause of premature topcoat breakdown.
• Repair without maintenance is temporary. The most critical factor you can control is moisture levels in the timber. Eliminate the moisture source or the repair will need repeating within years.

Conclusion

Exterior timber repair sits at the most demanding end of the DIY filler spectrum — and it's where product selection, preparation discipline, and layering technique matter most. The combination of Selleys No More Cracks Exterior Wood Filler for surface and moderate repairs, and Selleys Plasti-Bond Heavy Duty for structural rebuilding of deep voids, covers the full range of scenarios encountered on Australian homes: from a weathered fascia board to a split window sill to a damaged decking edge.

The principles here — excavate completely, layer methodically, cure fully, and protect the repair with primer and topcoat — apply across the entire exterior timber repair category. Follow them and you get professional results the first time. For readers working on interior surfaces, wall patches, or trim repairs, the broader series covers each scenario in depth: see How to Fill Cracks and Holes in Walls and Plasterboard for interior wall repairs, and Why Your Filler Keeps Cracking, Shrinking, or Falling Out for diagnosing and correcting any repair that hasn't performed as expected.

References

• ABIS Building & Pest Inspections. "Fungal Decay." ABIS, December 2025. https://abis.com.au/fungal-decay/

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

• Selleys Australia. "No More Cracks Exterior Wood Filler — Product Page." Selleys.com.au, 2024. https://www.selleys.com.au/products/putty-and-fillers/wall-filler/no-more-cracks-exterior-wood-filler/

• Selleys Australia. "Plasti-Bond Heavy Duty — Product Page." Selleys.com.au, 2024. https://www.selleys.com.au/products/putty-and-fillers/rigid-fillers/selleys-plasti-bond-heavy-duty/

• Building Conservation. "Timber Decay." buildingconservation.com. https://www.buildingconservation.com/articles/envmon/timber_decay.htm

• WoodWorks | Wood Products Council. "Do Wood-Frame Buildings Need to Account for Thermal Movement?" WoodWorks.org, February 2022. https://www.woodworks.org/resources/do-wood-frame-buildings-need-to-account-for-thermal-movement/

• Sandberg, J., Söderström, O., Wålinder, M. "Thermal Expansion of Wood at Different Equilibrium Moisture Contents." Journal of Wood Science, Springer Nature, 2019. https://link.springer.com/article/10.1186/s10086-019-1781-9

• Jim's Handyman. "How to Repair Wood Rot on Your House." jimshandyman.com.au, November 2025. https://jimshandyman.com.au/how-to-repair-wood-rot-on-your-house/

• Timber Information Service. "Timber Decay & Termites." timberinfo.com.au. https://timberinfo.com.au/timber-decay-termites/

Frequently Asked Questions

What is Selleys No More Cracks Exterior Wood Filler used for: Filling cracks, splits, and holes in exterior timber

Is Selleys No More Cracks Exterior Wood Filler waterproof: Yes, once fully cured

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

Will Selleys No More Cracks Exterior Wood Filler crack after application: No, it will not crack

Will Selleys No More Cracks Exterior Wood Filler split after application: No, it will not split

Will Selleys No More Cracks Exterior Wood Filler fall out: No, it will not fall out

Can Selleys No More Cracks Exterior Wood Filler be sanded: Yes

Can Selleys No More Cracks Exterior Wood Filler be nailed: Yes

Can Selleys No More Cracks Exterior Wood Filler be planed: Yes

Can Selleys No More Cracks Exterior Wood Filler be painted: Yes

Can Selleys No More Cracks Exterior Wood Filler be stained: Yes

Can Selleys No More Cracks Exterior Wood Filler be varnished: Yes

Can Selleys No More Cracks Exterior Wood Filler be tinted: Yes

Is Selleys No More Cracks Exterior Wood Filler water-based: Yes

What is the cleanup method for Selleys No More Cracks Exterior Wood Filler: Water, before drying

Is priming required before applying Selleys No More Cracks Exterior Wood Filler: No, it bonds directly to clean timber

Should primer be applied after Selleys No More Cracks Exterior Wood Filler cures: Yes, before topcoat

What is the maximum layer thickness per application of No More Cracks Exterior Wood Filler: 10mm per layer

Can No More Cracks Exterior Wood Filler fill deep voids in a single pass: No, apply in 10mm layers

What is the surface dry time for No More Cracks Exterior Wood Filler in warm conditions: 1–2 hours

What is the through-dry time for a single layer of No More Cracks Exterior Wood Filler: 2–4 hours

How long before sanding and priming a deep layered repair: 24 hours minimum

What is the minimum application temperature for No More Cracks Exterior Wood Filler: 5°C

Should No More Cracks Exterior Wood Filler be used in direct sun above 35°C: No, work in shade

Should uncured No More Cracks Exterior Wood Filler be exposed to rain: No

What is Selleys Plasti-Bond Heavy Duty used for: Structural rebuilding of deep timber voids

Is Selleys Plasti-Bond Heavy Duty a two-part product: Yes, it requires hardener activation

What is the working time for Selleys Plasti-Bond Heavy Duty: Approximately 20 minutes

What is the set time for Selleys Plasti-Bond Heavy Duty: Approximately 20 minutes without shrinking

Does Selleys Plasti-Bond Heavy Duty shrink when curing: No

What is the temperature resistance of Selleys Plasti-Bond Heavy Duty: -28°C to +190°C

Is Selleys Plasti-Bond Heavy Duty resistant to fresh water: Yes

Is Selleys Plasti-Bond Heavy Duty resistant to salt water: Yes

Is Selleys Plasti-Bond Heavy Duty resistant to acids: Yes

Is Selleys Plasti-Bond Heavy Duty resistant to alkalis: Yes

Can Selleys Plasti-Bond Heavy Duty be drilled: Yes

Can Selleys Plasti-Bond Heavy Duty be sawn: Yes

Can Selleys Plasti-Bond Heavy Duty be filed: Yes

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

When can Selleys Plasti-Bond Heavy Duty be painted: After approximately 30 minutes

When is Selleys Plasti-Bond Heavy Duty ready for sanding and filing: Approximately 30 minutes after mixing

What hardener ratio is used for Selleys Plasti-Bond Heavy Duty: 2.5cm hardener per 20ml of compound

Which product is the base layer for deep exterior timber repairs: Selleys Plasti-Bond Heavy Duty

Which product is the finishing layer for exterior timber repairs: Selleys No More Cracks Exterior Wood Filler

Can interior wood fillers be used for exterior timber repairs: No, they will break down

Can standard Spakfilla be used for exterior timber repairs: No

What is the primary cause of exterior timber rot: Fungal decay combined with moisture

What is the most common house timber decay fungus in Australia: Coniophora species (brown rot)

What are the two types of rot that affect window joinery: Brown rot and white rot fungi

What does brown rot do to timber structure: Attacks cellulose, causing cubical fracture

Where does exterior timber rot most commonly begin: End grain, pooling water points, and stressed paint areas

What is the probe test used for: Assessing depth and extent of timber rot

What does easy screwdriver penetration indicate during a probe test: Rot extends beyond the surface

What percentage of board thickness defines superficial rot damage: Less than 30%

What percentage of board thickness requires board replacement: More than 30–50%

Must all rotten material be removed before filling: Yes, without exception

Why must all rotten material be removed: Trapped moisture and fungi cause re-decay beneath the repair

What causes filler to fail on exterior timber: Moisture-driven timber movement cracking rigid fillers

How should deep void edges be prepared for better adhesion: Undercut slightly to create a mechanical key

What is the first step in repairing a split window frame: Stabilise with exterior-grade wood glue and clamp

How often should decks be cleaned and resealed: Annually

How often should protective stains be applied to fences: Every 2–3 years

What is the single most important step against future fascia rot: Aggressively prime all exposed end grain

What is the number one rule in preventing wood rot: Control moisture levels in the timber

What causes fascia board rot most commonly: Clogged or broken gutters causing water overflow

Is Selleys Plasti-Bond Heavy Duty suitable as a surface filler: No, it is a structural rebuilding compound

What size tub is Selleys No More Cracks Exterior Wood Filler available in: 450g tub

Does Plasti-Bond Heavy Duty require more hardener in cold weather: Yes

Does stain absorb identically into filler and surrounding timber: No, test on inconspicuous area first

What finish layer follows primer on a repaired exterior timber surface: Exterior-grade topcoat paint or stain

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 No More Cracks Exterior Wood Filler

• Product type: Weather-resistant flexible filler
• Formulation: Water-based
• Available size: 450g tub
• Waterproof: Yes, once fully cured
• Flexible: Yes, flexes with wood movement
• Will not crack, split, or fall out after application
• Sandable: Yes
• Nailable: Yes
• Planable: Yes
• Paintable: Yes
• Stainable: Yes
• Varnishable: Yes
• Tintable: Yes
• Cleanup method: Water, before drying
• Maximum layer thickness per application: 10mm
• Surface dry time (warm, low-humidity conditions): 1–2 hours
• Through-dry time (single layer): 2–4 hours
• Minimum through-dry time before sanding and priming a deep layered repair: 24 hours
• Minimum application temperature: 5°C
• Priming required before application: No
• Priming recommended after curing, before topcoat: Yes
• Application in direct sun above 35°C: Not recommended; work in shade
• Exposure of uncured product to rain: Not recommended

Selleys Plasti-Bond Heavy Duty

• Product type: Two-part plastic putty (requires hardener activation)
• Working time after mixing: Approximately 20 minutes
• Set time: Approximately 20 minutes without shrinking or cracking
• Shrinkage on curing: None
• Temperature resistance: -28°C to +190°C
• Resistant to fresh water: Yes
• Resistant to salt water: Yes
• Resistant to acids: Yes
• Resistant to alkalis: Yes
• Resistant to oils: Yes
• Drillable: Yes
• Sawable: Yes
• Fileable: Yes
• Sandable: Yes
• Planable: Yes
• Nailable: Yes
• Screws can be driven into cured product: Yes
• Paintable: Yes, after approximately 30 minutes
• Ready for filing and sanding: Approximately 30 minutes after mixing
• Hardener ratio: 2.5cm length of hardener per 20ml (heaped tablespoon) of compound
• Additional hardener required in cold weather: Yes
• Suitable substrates: Wood, plaster, brick, concrete, fibre cement, metal, alloys, ceramics, fibreglass
• Minimum application temperature: 5°C

General product claims

• Selleys No More Cracks Exterior Wood Filler is described as the go-to exterior timber filler for the vast majority of residential repair scenarios
• Selleys No More Cracks Exterior Wood Filler is stated to deliver lasting results that accommodate residual timber movement without cracking
• Interior fillers, including standard Spakfilla and interior-grade wood fillers, are claimed to break down within a single wet season when used in exterior conditions
• Selleys products are described as engineered specifically to handle conditions that defeat lesser alternatives
• Correct use of the layering technique (Plasti-Bond Heavy Duty base, No More Cracks Exterior Wood Filler finish) is claimed to produce professional results the first time
• Priming cured filler before topcoat is stated to significantly improve paint adhesion and longevity, particularly on horizontal surfaces exposed to UV and rain
• Aggressively priming all exposed end grain is described as the single most important step against future fascia rot
• Controlling moisture is described as the number one rule in preventing wood rot
• A correctly executed filler repair is described as restoring form and weather-resistance, with ongoing maintenance required for long-term performance