Best Fillers for Deep Holes in Walls and How to Choose the Right One

Repairing deep holes in walls can be a challenge, especially when you want a smooth, long-lasting finish. Choosing the best filler for deep holes in wall repairs is key to restoring your walls quickly and effectively. This guide will help you understand what to look for in a filler, the best types available in the UK, how to apply them properly, and common mistakes to avoid. Whether you’re fixing damage from nails, pipes, or accidental knocks, this post will help you pick the right product and get the job done well.

!Close-up view of deep hole in plaster wall before repair

What Actually Works for Deep Holes (From a Tradesman)

Deep holes aren’t all the same — the right repair depends on how deep it is and whether it’s internal or external.

If the hole goes right back to brick, don’t just fill over it.You need to seal the background first.

Use a penetrative sealer to prime the brick and stop it sucking the moisture out of your filler too quickly. Something like a basic exterior stabilising solution from Wickes works well for this. Then build it upwith Hardwall or bonding plaster first. both avaible at Wickes.

Building the Hole Back Up Properly

For deeper repairs, don’t rely on ready-mixed filler.

Instead, build it up using a powder filler like Drywall or bonding filler:

• Mix it so it holds on the trowel

• If it slides off, it’s too wet. If you apply toi the wall it will slump!

• Apply in layers and let it firm up properly

A good mix should be light, workable, and stay where you put it without slumping.

Avoid Ready-Mixed Fillers for Deep Repairs

Ready-mixed fillers are one of the biggest causes of failed repairs.

They:

• Take much longer to dry

• Rely on air and evaporation to set

• Contain retarders to stop them setting in the tub which effect drying times on wall.

👉 This means deep fills stay soft underneath and can shrink or crack later.

Powder fillers set through a chemical reaction, making them far more reliable for deeper holes.

Best Fillers to Use to topcoat finishes (Trade Picks)

External repairs:

• Toupret Tough Multi-Purpose Filler → strong, durable, good balance of strength and sandability

• Toupret Rock Solid Repair → very strong but very difficult to sand

• Toupret Exterior Repair Filler → easier to sand, but not as tough

Internal repairs:

• Easy Fill → great for large areas, easy to mix and apply, limited to 5mm - 20mm depth limit.

• Toupret Interior Filler → decent, but harder to mix smooth and not as easy to apply over bigger areas. doesnt stick well on shallow dips or holes.

• Toupret Quick Dry Interior → stronger and sticks well, better for smaller repairs but harder to finish neatly. Very do-able, but harder than the others.

• Toupret Quick Dry Joint Skim & Fill - smooth, easy to sand and quick drying. Not great for repairs, good for large area skims.

How to Apply

Applying filler correctly is essential for a strong, smooth repair. Follow these steps:

1. Prepare the hole

   Remove loose plaster, dust, and debris. For brick holes, clean out mortar dust and loose bricks.

   
   

2. Prime if needed

   Some fillers require a primer on very porous surfaces to improve adhesion.

   
   

3. Apply filler in layers

   For deep holes, apply filler in 10-20mm layers. Let each layer dry fully before adding the next.

   
   

4. Use the right tools

   A filling knife or trowel helps spread filler evenly. For very deep holes, a pointing trowel works well.

   
   

5. Sand between layers

   Lightly sand each dried layer to remove bumps and ensure good adhesion for the next layer.

   
   

6. Final sanding and finishing

   Once the last layer is dry, sand the surface smooth and wipe away dust before painting.

   
   

Common Mistakes

Avoid these errors to ensure your repair lasts and looks good:

• Filling deep holes in one go

Thick layers can crack or shrink. Always build up in layers.

• Adding too much water to the mix  

  Adding too much water makes the mix runny and heavier which causes it to slump.

• Skipping surface preparation

Dust and loose material prevent filler from sticking properly.

• Using the wrong filler for the wall type

For example, using plaster filler on brick can cause poor adhesion.

• Not allowing enough drying time

Rushing sanding or painting can ruin the finish.

• Ignoring primer on porous surfaces

This can cause the filler to dry too fast and crack.

FAQs About Filling Deep Holes in Walls

Do you need to seal brick before filling a hole?

Yes. If a hole goes back to brick or masonry, it should be sealed with a penetrative primer first. This prevents moisture being pulled out of the filler too quickly and helps it bond properly.

What should you apply after sealing the brick?

After priming, apply a base coat such as bonding plaster or hardwall to build the depth. This creates a solid backing before applying a finishing filler on top.

Can you fill a deep hole in one layer?

No. Deep holes should not be filled in one go, as this can cause cracking and shrinkage. Always build up in layers or use a base coat like bonding or hardwall first.

Why does filler crack in deep holes?

Filler usually cracks when it’s applied too thick, the surface hasn’t been sealed, or the wrong product has been used. Deep repairs need a proper base layer to prevent movement.

What is the best method for filling deep holes?

The correct method is:

1. Clean out the hole

2. Seal the surface if needed

3. Apply bonding or hardwall to build depth

4. Let it set

5. Apply a finishing filler like the ones listed

6. Sand and decorate

Is bonding or hardwall better for deep repairs?

Both are suitable. Bonding plaster is easier to apply and shape, while hardwall is stronger and better for tougher surfaces like masonry.

Can ready-mixed filler be used for deep holes?

Ready-mixed filler is not ideal for deep repairs because it dries slowly and can remain soft underneath. Powder fillers or base coats are more reliable.

How long should you wait before applying filler over bonding?

Wait until the bonding or hardwall has fully set and dried. Once firm, you can apply a finishing filler and sand it smooth before painting.

Choosing the best filler for deep holes in wall repairs depends on the hole size, wall material, and your finishing goals. Polyfilla Deep Fill is a reliable all-rounder for plaster and drywall, while cement-based fillers work best for brick. Applying filler in layers and preparing the surface properly will give you a smooth, durable repair.

Polyfilla vs Powder Filler vs Repair Mortar — Which Should You Use?

Not all fillers do the same job.

And one of the biggest mistakes people make is using a lightweight decorator’s filler where a structural repair product is needed.

👉 Match the filler to the repair.

Polyfilla / Ready-Mixed Fillers

Best for:

• Small dents

• Screw holes

• Fine surface cracks

• Light patching

Good for quick repairs, easy sanding and convenience.

But—

For deeper fills?

Not my first choice.

Many ready-mixed fillers shrink when used too thick.

Powder Fillers

For most wall repairs—

👉 This is the sweet spot.

Good powder fillers have:

• Less shrinkage

• Better strength

• Faster build-up

• Better sanding

Ideal for:

• Patching damaged plaster

• Medium to deep holes

• Skim repairs

• Crack repairs

This is what many decorators use daily.

Deep Hole Fillers / Heavy Duty Fillers

Toupret Patch & Repair Filler (Quick Dry Powder) no depth limit

When the hole is deeper or blown out—

Use a deep hole filler.

These are designed to:

• Be built up in layers, don’t fill all at once.

• Hold shape in bigger voids

• Dry hard without slumping

Much better than trying to force standard filler into large holes.

Repair Mortar / Bonding / Drywall Mud For Really Big Repairs

For large voids into masonry, blown plaster or brick showing—

👉 Standard filler may not be the first product you reach for.

This is where repair mortar or bonding plaster can make more sense.

Use them to rebuild depth first—

Then skim over with finish filler.

That usually gives a stronger repair.

Quick Rule of Thumb

Hairline cracks?Use finish filler.

Patching walls?Use powder filler.

Deep holes?Use deep hole filler.

Large damaged masonry?Use repair mortar or bonding first.

Use the right product for the size of repair—

Everything gets easier.

❓FAQ: Best Wall Fillers

What is the best wall filler?

For general repairs, a good powder filler is hard to beat. It offers strength, less shrinkage and sands well. Internal is Toupret Patch & Repair Filler (Quick Dry Powder) large areas, smaller areas Toupret TX110 Rapid Drying Interiorexterior - Toupret Touprelith F Exterior Masonry

Repair Filler For rock solid repairs- (Toupret Murex Rock Solid Exterior Filler

very difficult to sand)

What is the best filler for patching walls?

For most patch repairs, powder fillers are often preferred because they build well and feather nicely. Toupret Patch & Repair Filler (Quick Dry Powder) 

What is the strongest filler for walls?

For strength, deep hole fillers and some fibre-reinforced fillers are usually stronger than lightweight ready-mixed fillers.interior - Toupret TX110 Rapid Drying Interior exterior- Toupret Murex Rock Solid Exterior Filler

very difficult to sand)

What is the best filler for deep holes?

If you see masonary or brick, use powder Bonding or Drywall mud to build layers up to plaster. Use a proper deep hole filler or build in layers with bonding first for larger voids.

Trying to use standard surface filler for deep holes often causes shrinkage or cracking.

What filler should I use for large holes in plaster?

For large damaged plaster areas, rebuild depth first with bonding , Drywall mud or repair mortar, then skim over with finish filler.

What is the best filler for wall cracks?

For hairline cracks, standard finish fillers work well. You get them in a ready made tub, very fine and easy to sand. Use only 240grit sandpaper and above on these.

For recurring movement cracks, flexible fibre-reinforced fillers are often better.

Deep hole filler or repair mortar — which is better?

For deep plaster repairs, deep hole filler is often enough.

For damaged masonry or very large voids, repair mortar may be the better choice.

Polyfilla or powder filler — which is better?

For small cosmetic repairs, ready-mixed fillers like Polyfilla can be convenient.

For bigger repairs, powder filler is often stronger and better value.

What filler do decorators use most?

Many decorators carry powder fillers for most patching work, often paired with specialist deep fillers for bigger repairs. Toupret Patch & Repair Filler (Quick Dry Powder) and for exterior - Toupret Touprelith F Exterior Masonry Repair Filler