How to Fix Drywall Cracks Step by Step

Why Does Drywall Crack?

Often times, drywall will crack around stress points such as between joints or around the taped areas. Joints are where two sections of drywall meet. Common causes are insufficient framing and screws to support the weight of the drywall, truss lifting, and stress points like around doorframes due to poor taping and mudding.

However, I will say that large humidity and temperature changes can also be the culprit, particularly in homes that aren’t climate-controlled year-round. These changes can cause the drywall to expand and contract, exerting pressure on seams.

Yet another reason is home settling in the foundation from soil compacting over time. My parents lived near a rock quarry which utilizes large dynamite blasts that creates shockwaves through the bedrock. This causes a settling effect with vertical cracks along seams, particularly around door frames or openings. It also cracked the grout in their floor tile that I had to repair.

Take the time to investigate and repair the source of the drywall stress before repairing the drywall to avoid a repeating problem.

Joint Compound vs Spackle

Joint compound (example) comes in various pre-mixed consistencies, such as lightweight, all-purpose, and feather light. The lighter weight takes less stress but is easier to feather thin layers.

Joint compound is more suitable for larger repairs than spackle. Joint compound is primarily used for embedding join tape, covering seams, and finishing joints between sheets of drywall.

Spackle (example) is quite different and is primarily designed for small drywall repairs such as picture frame nail holes or nail pops. It is not intended for use in larger drywall finishing projects or taping joints.

What is Hot Mud?

Hot Mud (example here) is a yet another type of joint setting compound that comes in powder form. You add water to it and a chemical reaction occurs which causes the mud to become warm and to harden in much less time than it takes traditional mud to dry. 

The primary use of hot mud is by drywall finishing professionals because drywall can be finished and feathered much faster, many times in the same day.

Because it sets up much quicker, it is more difficult for beginners to work with. If you are inexperienced with patching drywall, you may find that it starts to harden on you before you can finish, so start with smaller batches.

Additionally, hot mud doesn’t sand smooth, so you can’t leave excess on the wall. You will need a finish coat of joint compound or feather finishing coat to ensure a nice transition that covers the crack.

Types of hot mud are delineated by their set up or working times (20, 45, and 90).

Which Joint Compound Should I use?

For most surface level cracks or cracks around tape edges, I would recommend that pre-mixed all-purpose joint compound is perfectly fine to use for the repair.

However, Hot Mud is definitely stronger, dries faster, and less prone to cracking than pre-mixed joint compound. Hot mud is certainly better to use under the tape in large cracks or gaps or between sheets of drywall. You will still need at least one finishing coat of sandable joint compound.

How to Prep Your Wall

1. Check for movement by moving along each side the cracked drywall and pushing with your thumb. If you see or feel movement, that generally indicates that the dry wall needs to be secured with additional drywall screws (to framing) to eliminate movement.
2. Old plaster like I did in repairing textured ceilings requires a slightly different approach. If it is thick plaster, you may need to secure the edges with plaster buttons.
3. Sheetrock panels should line up to end over top of a joist or wood stud, but I had to fix a wall crack that happened because the edges of the drywall sheets did not line up with the studs – the installers literally wallpapered over it to cover their mistake. If there is no stud behind your drywall seam, you should cut either side back to the center of the nearest stud and rehang a fresh section of drywall.

1. Apply Thin Layers. Gradually build up thin coats, applying subsequent layers slightly wider than the previous ones. Thin layers dry quicker and are easier to blend.
2. Feathering Technique. Feathering drywall refers to angling the blade of a drywall knife so that you don’t leave thick edges. When applying drywall mud, use a feathering technique to taper the edges of the repair area outward.
3. Use a Wide Knife. Use a wide drywall knife to feather the edges. Small repairs can use a 6-inch blade, but wider blade (10 to 12-inch) helps distribute the compound more evenly and makes it much easier to achieve a smooth transition.

4. Sand Between Layers. Lightly sand each layer before applying the next. This should smooth out any imperfections or burrs to creates a better surface for the next layer to adhere.
5. Blend with Surrounding Wall. Extend each layer beyond the repaired area, gradually blending it into the surrounding wall. As a general rule, 12-18 inches on either side of the seam helps to eliminate any noticeable transition lines.
6. Use a Sanding Block. I like sanding sponges or blocks better because they keep even pressure for a smoother drywall surface.
7. Check with a flashlight. I like to use a flashlight set at angles around the patch area. Shadows reveal imperfections you may not see until painting.

What kind of tape do I use?

The thing is that there are many ways to do drywall and factors include your budget, experience, and situation.

Paper Tape. Paper tape gets a bad rap. IT is the most common tape and used in most new home builds as it’s the least expensive option. It can be difficult to work with but works well if installed properly.

Mesh tape or Fibafuse. These products are generally what I use. They are just easier to work with and sand around and cheaper than composite tape. FibaFuse and FibaTape are different products. FibaTape is a mesh tape while Fibafuse aims to combine the best qualities of paper and mesh tapes. It’s stronger than mesh tape, won’t bubble like paper tape, and fuses chemically with pre-mixed joint compound to create a strong bond.