You don’t need to be an expert to repair cracks, dents, or holes in walls and concrete caused by various reasons in your home. We explain practical methods and materials you can use to fill holes and fix cracked walls. Plus, at the end of the page, we answer many common questions about wall crack repairs.
How to Repair Holes and Cracks in Walls and Concrete?
When repairing a hole or crack in a wall, it’s important to use the right material based on its size. Determine whether the wall crack is caused by paint, plaster, or the wall itself, and apply the appropriate repair method. Additionally, you may need different materials for holes and cracks.
Some fine cracks in walls may result from paint. In such cases, a light sanding may be sufficient. However, if the plaster or wall is damaged, a more thorough repair will be necessary. Let’s dive into the details!
How to Fix Holes and Cracks in Walls and Concrete?
To repair holes and cracks in walls, you can use ready-made repair putty, finish plaster, skim coat, polyurethane sealant, or even paint. But which one should you use for different types of wall cracks?
1-Ready-to-Use Wall Fillers
Ready-made wall crack fillers are excellent materials for quick repairs. They are sold in toothpaste-like tubes or buckets and are suitable for fixing hairline cracks, small gaps, and holes in walls.
You can also use ready-made fillers to cover holes in walls. These fillers are similar to plaster, with a consistency almost identical to pre-mixed plaster.
To use, apply the wall crack filler over the hole or crack, smooth it out with a spatula, and let it dry. Once dry, sand the area with 180-grit sandpaper. If needed, you can then apply primer and paint for a polished finish.
2-Polyurethane Sealants
Polyurethane sealants are similar to silicone, but their primary purpose is to fill gaps. Since they are paintable, polyurethane sealants are an excellent choice for sealing wall cracks.
They are also weather-resistant, making them suitable for both indoor and outdoor use to repair wall cracks or fill holes. Polyurethane sealants work well for cracks or plaster repairs about the width of a pencil or fountain pen. Apply the sealant to the crack using a caulking gun, let it dry for a day, and then cover it with plaster or ready-to-use repair putty before painting. Alternatively, you can paint directly after it dries.
Sealants are commonly available as acrylic or polyurethane types. Polyurethane sealants are more flexible, adhesive, and durable. However, for fine hairline cracks, ready-made repair putty or satin plaster is a better option.
3-Finish Plaster
If the crack in the wall is as thin as the tip of a pencil, you can cover it with finish plaster. The most common method used for wall crack repair is finish plaster. For thick and deep cracks, you should use base coat plaster, while for fine, superficial cracks, satin plaster is more appropriate.
Before painting the wall, cracks should be repaired with finish plaster. Mix finish plaster with water to achieve a soft, dough-like consistency and apply it to the cracks or holes on the wall using a metal spatula. After allowing it to dry for a day, you can apply primer and paint.
If you’re using finish plaster to cover wall holes, you first need to prepare it and get the right consistency. Repairing wall cracks or covering holes with finish plaster requires more effort than ready-made putty, but it’s a more suitable material for large repairs. For larger areas, satin plasters may be more economical.
Finish plaster is ideal if the wall surface is peeling or if small holes have formed. It is the final coat of plaster applied to create a smoother surface.
Knead the finish plaster thoroughly with a spatula until it reaches a soft, paste-like consistency. Apply it to the repair surface by pressing it in. For a smooth finish, once the plaster has dried, you can sand it with 180, 200, or 220-grit sandpaper and then paint.
4-Base Coat Plaster
Base coat plaster is a thick type of plaster. It is used to fill gaps approximately the size of a fist or larger. It is also applied to the entire wall before finish plaster.
If the cracks in the wall are 3-4 inches wide or larger, base coat plaster is more suitable. After the base coat plaster dries, you can apply satin plaster on top to achieve a smoother surface. Then, sand it down, apply primer, and paint.
5-Paint
Small plaster repairs may leave marks on the wall. In this case, painting might be the best option. For a fine paint crack, a few coats of paint will be sufficient. If the crack on your wall is a fine crack caused by paint, simply sand it with 180-grit sandpaper and repaint the surface. However, there may be color tone differences between the old and new paint.
Frequently Asked Questions
Below, we’ve answered the most frequently asked questions about wall crack repairs. If you have any other questions, feel free to ask.
How do You Permanently Fix Cracked Walls?
Prepare the Crack: Clean the crack and remove any loose material.
Apply Joint Compound: Spread a layer of joint compound (also known as drywall mud) over the crack.
Place the Drywall Tape: Press the drywall tape (paper or fiberglass mesh) into the wet joint compound, ensuring it covers the entire crack.
Cover with More Compound: Apply another layer of joint compound over the tape, smoothing it out with a putty knife.
Let it Dry: Allow the compound to dry completely.
Sand the Area: Once dry, sand the area to create a smooth finish.
Prime and Paint: Apply primer and paint to blend the repair with the surrounding wall.
What is The Best Way to Fill Cracks in Walls?
The best way to fill cracks in walls depends on the size and type of crack. Here’s a general guide:
Small Hairline Cracks:
Use Wall Filler or Spackling Paste: For small, fine cracks, use a ready-to-use wall filler or spackling paste. Apply with a putty knife, smooth it out, and allow it to dry before sanding.
Medium to Large Cracks:
Use Joint Compound and Drywall Tape: For larger cracks, apply a layer of joint compound over the crack. Use drywall tape (paper or fiberglass mesh) to reinforce the crack, then cover it with more compound. Once dry, sand and smooth the surface.
Deep or Wide Cracks:
Use Bonding Plaster or Base Coat Plaster: For deep or wide cracks, start with bonding plaster to fill the crack. After it dries, apply a finish plaster or skim coat for a smooth surface.
Cracks Due to Movement (e.g., settling or foundation issues):
Use Polyurethane Sealant: If the crack is caused by movement or settling, use a flexible material like polyurethane sealant. It allows for some expansion and contraction without cracking.
Finish and Paint: Once the crack is filled and smooth, prime and paint the wall to blend the repair with the surrounding area.
How to Repair Deep Cracks in Plaster Walls?
Clean the Crack: Remove loose plaster and debris.
Widen the Crack: Use a utility knife to create a V-shape for better adhesion.
Apply Bonding Plaster: Fill the crack with bonding plaster to fill the depth of the crack.
Smooth the Surface: Apply a finish plaster or skim coat to level the surface.
Let It Dry: Allow the plaster to dry completely.
Sand and Paint: Sand smooth, then prime and paint to match the surrounding wall.
Can I Just Paint over Cracks in Walls?
Deep cracks need to be repaired before painting. However, if the crack in the wall is caused by the paint, you can simply sand it with a fine-grit sandpaper and paint directly.
Can You Plaster over Cracked Walls?
Yes, you can plaster over cracked walls. First, clean the crack and remove any loose material. If necessary, widen the crack for better adhesion. Apply a bonding agent for deep cracks, then spread plaster over the crack using a putty knife. Smooth the surface and let it dry completely. Once dry, sand the area and finish with primer and paint for a seamless repair.
Does Primer Fill in Cracks?
Primer can cover fine paint cracks. However, before using primer, the cracked wall needs to be sanded. Applying multiple coats of both primer and paint can also help cover the crack.
How to fill in Hairline Cracks?
To fill in hairline cracks, start by cleaning the crack and removing any loose debris. Apply a thin layer of wall filler or spackling paste with a putty knife, pressing it into the crack. Smooth the surface and allow it to dry completely. Once dry, sand it lightly to create a smooth finish, then apply primer and paint to blend the repair with the rest of the wall.
What is The Best Filler for Cracked Plaster?
The best filler for cracked plaster is a plaster repair compound or joint compound. For deep cracks, use bonding plaster to fill the gap and ensure a strong bond. For surface-level cracks, finish plaster or ready-to-use wall fillers work well to smooth out the surface. These fillers provide strong adhesion, flexibility, and a smooth finish for a long-lasting repair.
