Which Selleys filler do you need, and how do you choose between them?

Putties and gap fillers are designed for filling gaps, cracks and holes on and between surfaces. The Selleys range covers more than thirty of them, and the sheer number is what makes the category hard to shop. Almost all of the choice collapses to one question, which Selleys itself puts at the top of this category: is the surface going to move?

Use a rigid gap filler for cracks and holes in flat surfaces such as walls and ceilings. Use a flexible filler for gaps and cracks between surfaces, such as between skirting boards. Get that right and the remaining decisions — indoor or outdoor, what the surface is made of, and whether colour matching matters — narrow the field to two or three products.

What this category covers

Selleys frames the choice around three factors: indoor or outdoor, what the surface is like, and whether colour matching is important to you. The range divides into four sections, and knowing which one you are in gets you most of the way there.

• Gap filler — flexible fillers that stay flexible once cured, for joints between surfaces where movement occurs.
• Wall filler — rigid fillers for cracks, chips, holes and dents in surfaces that are not expected to move or flex.
• Wood putty — putties for timber and glazing work.
• Specialist fillers and putty — epoxy putties and purpose-built compounds for repairs the general fillers do not cover.

How to choose

Gaps between the wall and skirting boards, cornices or frames

For gaps or cracks between the wall and skirting boards, cornices, or window and door frames inside your home, Selleys directs you to the No More Gaps Interior range. These flexible fillers accommodate building movement without cracking or damaging other surfaces.

That phrase — without damaging other surfaces — is worth pausing on. A joint that moves has to put that movement somewhere. If the filler is too rigid to absorb it, the stress transfers into whatever is weakest nearby, which is often the paint film or the plaster edge rather than the filler itself. A flexible filler takes the movement instead.

Your options here are No More Gaps Interior Multipurpose, which delivers a smooth finish with superior flexibility and low shrinkage, and No More Gaps Interior Fast Dry where the schedule is tight.

Damp or humid areas

In damp or humid areas — other than for gaps around baths, sinks and in showers — Selleys specifies No More Gaps Bathroom & Kitchen. It is water-resistant and contains a fungicide to protect against mould.

Read the exclusion carefully, because it is the most commonly missed instruction in this category. The gaps around a bath, a sink or inside a shower recess are not what this filler is for. Those are sealing jobs for a wet area silicone, not filling jobs, and they belong in wet area silicone. Bathroom & Kitchen filler is for the rest of the room — the skirtings, the frames, the cornices in a space that happens to be humid.

Timber flooring and panels

For covering gaps, cracks and holes on interior timber flooring and panels, Selleys specifies No More Gaps Timber Floors. It is designed for filling gaps around and between tongue and groove timber flooring, and between other timber panels and fittings.

The distinguishing feature is that it contains real wood fibres, which means it can be sanded and stained once dry. That matters on a floor: a filler that will not take stain leaves a pale line running the length of every board join, which is more conspicuous than the gap you started with.

Bricks and mortar, and exterior work

Selleys names No More Gaps Bricks & Mortar and No More Gaps Exterior for closing gaps and cracks in bricks and masonry. Both are flexible, so they allow for building movement, and both can be used on interior and exterior surfaces without weathering.

Where colour matching matters

No More Gaps Coloured Gaps gives a seamless finish without the need to paint afterwards. That is the deciding factor when you are filling against a finished surface you would rather not repaint.

Cracks and holes in a flat wall or ceiling

This is rigid filler territory. The Spakfilla products are pre-mixed and water-based, need only a single application, are fast drying, and can be sanded and painted once dry — Spakfilla Rapid for quick small repairs, Spakfilla Heavy Duty for larger gaps and cracks, and Spakfilla Colour Smart where the repair is going to be painted.

Where you need more than Spakfilla, the No More Cracks powder fillers take over. No More Cracks Interior Powder Filler is for plaster, plasterboard, bricks and wood that is not exposed to the elements. No More Cracks Exterior Powder Filler gives weather and water resistance, but Selleys is explicit that it is for masonry work only.

Timber and glazing

Selleys Special Putty is a linseed oil-based putty for fitting windows into wooden frames, and for joinery and some plumbing work. Selleys Woodfilling Putty fills nail holes, cracks and minor flaws in timber. Both are developed for timber and should not be used on metal window frames.

Structural and specialist repairs

The specialist range is where the epoxy putties sit — Knead It Steel for metal, Knead It Aqua for plumbing and underwater repairs, Knead It Autofix for car repairs, and Knead It Multipurpose for general work. Fireproof Cement covers fireplaces and chimneys, and Tradie's Bog gives fast, sandable repairs to timber and most common building materials.

The safety divide across the filler range

Everything above sorts this category by whether the surface moves. Hazard sorts it a different way, and the result is counter-intuitive: the fillers that go into the largest voids and the ones that set hardest are the classified products, while the ordinary interior pastes mostly are not. Six products carry Danger, and five of the six sit at the specialist and large-gap end of the range.

Group	Products	Classification
Isocyanate foams — Danger	No More Big Gaps, Pro Trade Expanding Foam	Eleven statements, including H334 may cause asthma if inhaled, H351 suspected of causing cancer, H372 organ damage, H362 may harm breast-fed children, plus H222/H229 as flammable aerosols
Polyester two-packs — Danger	Tradie's Bog, Plasti-Bond Heavy Duty	Hardener is an organic peroxide, Type E — H242 heating may cause a fire — with H317 and H319. Tradie's Bog's filler half adds H361 suspected of damaging fertility or the unborn child, H372, H226, H315, H335
Cement-based — Danger	Exterior Powder Filler, Fireproof Cement	H318 or eye damage Category 1, H315, and respiratory tract irritation (H335) from the dry powder. Exterior Powder Filler is 10–30% Portland cement
Epoxy putties — Warning	Knead It Steel, Knead It Multipurpose, Knead It Autofix	Skin sensitisation Category 1 or 1A, skin irritation Category 2, eye irritation
Acrylic pastes — Warning	The No More Gaps range, the Pro Trade gap fillers, most of the No More Cracks and Spakfilla fillers	H317 may cause an allergic skin reaction, some adding H319
Not classified as hazardous	No More Gaps Interior Multipurpose, Interior Powder Filler, Interior Wood Filler, Doors & Trims, Spakfilla Heavy Duty, Woodfilling Putty	No signal word, no hazard statements

Interior and exterior versions of the same product are not equivalent on hazard, and that is the trap. Interior Powder Filler is not classified at all; Exterior Powder Filler is 10–30% Portland cement and is Danger, with serious eye damage rather than irritation. Interior Wood Filler is not classified; Exterior Wood Filler is Warning with H317. In both pairs the bag or tub looks the same, mixes the same and is used with the same tools, so the habits transfer while the hazards do not. Goggles and a P2 mask belong with the exterior powder, not just gloves.

The expanding foams are the most hazardous products in this category, with eleven hazard statements including respiratory sensitisation and suspected carcinogenicity, and they are used in the worst places for it — wall cavities, roof spaces, subfloors and window reveals. Ventilate actively, wear an organic vapour respirator rather than a dust mask, and keep anyone breastfeeding away from both. The gap filler section sets this out in full.

The two-part polyester fillers carry a hazard that has nothing to do with using them. H242 — heating may cause a fire — is an organic peroxide classification on the hardener tube in Tradie's Bog and Plasti-Bond Heavy Duty. It is a storage hazard: peroxide hardeners degrade and can self-heat if they sit somewhere hot, which is precisely where a half-used tube tends to end up, in a toolbox in a ute or on a shelf in a tin shed. Keep the hardener cool, and do not keep an old one indefinitely. Tradie's Bog adds H361 on the filler half — suspected of damaging fertility or the unborn child — so sanding and mixing it is not a job for someone pregnant.

Six products carry no classification at all, and between them they cover the great majority of ordinary household filling: interior gaps between surfaces, interior walls and ceilings, interior timber, door frames and trims, large interior repairs, and nail holes in joinery. If the constraint is a nursery, an asthmatic household, sensitive skin or a confined space, the answer is almost always in that list rather than in a compromise on the job.

Comparing the fillers on the number the category is built around

The whole page above turns on one question — will the surface move — and it is treated as a yes or no. It is not. The flexible fillers publish movement capability figures spanning a factor of two and a half, so "use a flexible filler" is not by itself an answer to a moving joint.

Product	Movement capability	Skin time	Published limits
No More Gaps Exterior	±25% (ISO 9046)	30 ± 5 minutes	Maximum gap 10 mm wide × 5 mm deep
No More Gaps Timber Floors	25% (ISO 9046)	30 minutes	See product page
No More Gaps Bathroom & Kitchen	±25%	20 minutes	Not for gaps around baths, sinks or inside showers
No More Gaps Coloured Gaps	±20% (ISO 9046)	3 minutes	Cure 4 mm in 24 hours; 8 mm in 72 hours
No More Gaps Interior Fast Dry	Up to ±10% (ISO 9046)	6 minutes	Only where joint depth is not greater than half the joint width; Shore A hardness >40
Pro Trade Gap Filler Fast Skin	±10% (ISO 9046)	6 minutes	Cure 24–48 hours
No More Gaps Bricks & Mortar	See product page	30 minutes, weather dependent	See product page
No More Big Gaps	Not published — expanding foam	Not applicable	A 3–5 cm deep application fully cures in about 5 hours
The wall filler range	Rigid — none published	Sand and paint from 30 minutes to 24 hours by depth	Interior and exterior variants are not interchangeable

The flexible range spans ±10% to ±25%, and the difference decides whether the bead survives. On a 10 mm joint, ±25% is 2.5 mm of travel in each direction and ±10% is 1 mm. A skirting-to-wall line in a timber-framed house moves with the seasons, and a joint asked for more than the filler can give does not fail gradually — it tears along one edge, usually the harder one, which is the hairline crack that reappears every winter after the wall was filled and painted. The high-movement products here are Exterior, Timber Floors and Bathroom & Kitchen at ±25%.

The trade-off has a physical reason you can read straight off the specification. Interior Fast Dry publishes a Shore A hardness above 40 alongside its ±10% movement figure; it is the only flexible filler in the range that publishes hardness at all, and it is also the one with the lowest movement. Hardness and extensibility pull against each other: a filler formulated to dry fast and sand hard has less give. That is the mechanism behind the trade-off, and it means you cannot get a fast, hard, highly extensible filler by shopping harder — the product does not exist because the chemistry does not allow it.

One joint-design rule appears on a single product page and applies to all of them. Interior Fast Dry qualifies its ±10% with "in expansion joints where depth is not greater than half the joint width". That ratio governs how any flexible filler behaves: a bead that is deeper than it is wide is bonded on three sides and cannot stretch, so it tears no matter what the movement figure says. No More Gaps Exterior expresses the same idea as a maximum — 10 mm wide by 5 mm deep, exactly two to one. If the gap is deeper than half its width, pack the bottom with backing rod rather than filling it solid, and that single change will do more for the joint than moving up a product.

Common questions

What is the difference between a rigid and a flexible filler?

Rigid fillers are for cracks and holes in flat surfaces such as walls and ceilings, on surfaces not expected to move or flex. Flexible fillers are for gaps and cracks between surfaces — the skirting-to-wall line, for example — and stay flexible once cured so they can absorb building movement.

Which filler do I use around a bath or in a shower?

None from this category. Selleys directs No More Gaps Bathroom & Kitchen at damp and humid areas other than gaps around baths, sinks and in showers. Those are sealing jobs — see wet area silicone.

Can I stain over a filler on a timber floor?

No More Gaps Timber Floors contains real wood fibres and can be sanded and stained once dry. That is the product specified for tongue and groove flooring and timber panels.

Which fillers can I use outside?

No More Gaps Exterior and No More Gaps Bricks & Mortar are both described as usable on interior and exterior surfaces without weathering. No More Cracks Exterior Powder Filler gives weather and water resistance but is for masonry only.

Do I have to paint over the filler?

Not with No More Gaps Coloured Gaps, which is designed to give a seamless finish without painting afterwards. The Spakfilla products are sanded and painted once dry.

What if the wall filler needs to hold a large hole?

Spakfilla Heavy Duty is described for filling large gaps and cracks in walls and ceilings, and No More Cracks Large Cracks & Holes covers large cracks and holes in interior and exterior surfaces.

Can I use a wood putty on a metal window frame?

No. Selleys states that both of its specialist putties are developed for use with timbers and should not be used on metal window frames.

Which product do I use if I need to mould the filler by hand?

Plasti-Bond Heavy Duty is a plastic putty that can be shaped before it hardens, which is what to use where a bead or a trowelled patch will not do.