Home Improvement Interior Remodel Walls & Ceilings Drywall

How to Use Drywall Shims

Straightening Drywall With Shims for an Even Surface

Updated on 05/17/23

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What Are Drywall Shims?

Drywall shims are strips of cardboard that increase the forward reach of a stud (that is, the stud's width) so that the drywall hangs better on the stud.

Drywall shims are not to be confused with window or door shims, which are short, tapered, and made of wood or plastic.

Since they are constructed of water-soluble cardboard, drywall shims should never be used for framing windows or exterior doors. Also, they should not be used for plasterwork since the water from the plaster would cause the shims to become pulp-like.

Hard cardboard that does not compact under pressure is the source of drywall shims. Other materials, such as corrugated cardboard, would compact too far.

While drywall shims can be duplicated for free by slicing up old cardboard, veneer board, or even tar paper, cardboard drywall shims are far easier to work with.

Do I Need to Use Drywall Shims?

In home remodeling, not all is perfect because you are dealing with the consequences of time, demolition, or even poor decisions made decades ago by builders and homeowners.

Warped, Twisted, or Bowed Studs and Joists

Often, after you have removed the older drywall or plaster, you will find individual studs or joists that are warped, twisted, and bowed. This is especially common when the previous wall covering was plaster since the lath-and-plaster system is excellent at compensating for imperfect stud assemblies. Those warped, twisted, and bowed studs benefit from shimming partial sections.

Studs and Joists Aren't Even

Sometimes, the very act of removing old drywall will bring studs out of line when overambitious workers knock studs slightly back. Another condition is when a number of studs, even if they are in good condition, are not far in or out enough to match your other work. This section of studs might be just 1/8 inch back from an adjacent section of studs.

The occasional stud that is too far back can be shimmed from top to bottom. That entire section of studs that doesn't match its neighboring section can be shimmed forward by 1/8 inch.

Drywall Shims Specs

At 45 inches long, drywall shims are the perfect length because they are the same length as the width of a sheet of drywall or half of an 8-foot length. In either sense, shims are cut perfectly to size for working with full sheets of drywall.
At 1 1/2 inches wide, drywall shims are the width of a stud, reducing width waste and the need for long cuts.
At about 1/16-inch thick, drywall shims are thin enough to correct shallow irregularities but can be stacked to address worse problems.

Equipment / Tools

Staple gun
Staple gun staples
Laser level or chalk line
Drywall installation tools
Pencil

Materials

Cardboard drywall shims/100-pack

How to Use Drywall Shims

Take Measurements

Use a chalk line or laser level to determine how much the defective joists or studs need to be shimmed for the drywall.

If dealing with a section of defective studs or joists that are all different distances, write individual measurements on each stud or joist with a pencil.
Place the Shim(s)

Lay a shim (or multiple shims) against the stud or joist until it reaches a point consistent to the level point.
Staple the Shims
- With your staple gun, staple the shims in place against the stud.
- Continue installing drywall shims for all of the studs.
Generally, shims are less effective beyond three or four of them stacked, because the staple is not long enough to reach the stud. Another reason is that the eventual drywall screw or drywall nail will have less wood to grab onto.
Check the Level

Make one final check for level by using your laser level or chalk line.
Install Drywall

Install the drywall as normal, using a drill, drywall screws, and drywall.

How to Make Drywall Shims

Corrugated cardboard used for boxes does not work well for making drywall shims because this material will compact and flatten. Instead, use thin, non-corrugated cardboard.

With the drywall square, measure out and cut strips of cardboard that are 1-1/2 inches wide by no more than 8 feet long.

Where to Buy Drywall Shims

Most large home improvement stores will carry 100-count bundles of drywall shims in the drywall section of the lumber department. The shims will typically be located in the tools and accessories section of this drywall area.

Because they are not commonly used by homeowners, drywall shims might be on a higher shelf or away from immediate view. You can also find them on Amazon.
FAQ
- How do you level a wall for drywall?
  
  Besides using shims, you can use sandpaper or a wood planer to level problematic studs, or use extra layers of drywall glue. The method you use will depend on the amount of leveling that needs to be done.
- What is the difference between a wedge and a shim?
  
  A shim is a thin wedge. A wedge is a piece of material that stays in its shape without any malleability. A shim is much thinner than a wedge and has some malleability so it can make contact with the stud and the drywall.
- Why does drywall need a gap at the bottom?
  
  A small 1/2-inch gap is typically needed so the drywall does not crack when the floor and wall go through natural expansions and contractions. The gap also prevents the drywall from wicking up minor water mishaps or standing water on the floor.