What is a Wood Shim and Its Common Uses: A Comprehensive Guide

wood shims

Whether you are a seasoned professional in the construction industry or a passionate DIY enthusiast, certain tools and materials become indispensable companions in your journey of crafting and building. While tape measures, hammers, and circular saws often steal the spotlight, one often overlooked hero of the trade is the humble wood shim. Despite its unassuming appearance, this small wedge of wood packs a powerful punch, offering a myriad of practical uses in various projects.

What Exactly is a Wood Shim?

A wood shim is a wedge-shaped piece of wood utilized to prop, adjust, hold, or fine-tune the position of objects. These wedges taper from less than 1/32-inch at their tip to ¼-inch at their thickest point, offering precision and versatility. Typically sold in packs of 12, 42, or 100, wood shims are not only practical but also incredibly cost-effective.

Wood shims are primarily crafted from softwoods such as pine or fir due to their ease of cutting and shaving. The softer wood variety is less prone to snapping or splitting when nails or screws are driven through them. Additionally, cedar shims are available and are particularly useful for outdoor or wet applications, boasting enhanced resistance to rot. For those seeking alternatives, plastic shims are also readily available in the market.

Understanding The Different Sizes of Wood Shims

  1. ¼” x 1¼” x 7¾”: This size reigns as the most common variant, ideal for hanging doors, windows, and filling other gaps with precision.
  2. ¼” x 1¼” x 11¾”: Equally prevalent, these longer shims are invaluable for spanning larger gaps, such as those encountered during trim work, cabinetry, or flooring installations.
  3. Larger shims in assorted sizes: These shims, sourced from off-cuts of cedar shingle production, offer versatility in various tasks, boasting durability and ease of manipulation.

Common Uses For Wood Shims

1. Trim Work

Wood shims prove indispensable when installing baseboards, crown moulding, or other trim components. They help bridge tiny gaps caused by irregularities in drywall or floor surfaces, ensuring a snug and seamless fit.

2. Cabinetry

Achieving flat and level cabinetry installations is crucial for both aesthetic appeal and functionality. Cabinet installers rely on shims to maintain uniformity and stability, ensuring that countertops sit flush and doors close smoothly.

3. Installing Doors and Windows

During rough framing, windows and doors are installed in openings larger than their actual dimensions. Wood shims come to the rescue, allowing builders to adjust and align these fixtures precisely, ensuring a snug fit and optimal performance.

4. Floor Flattening

Whether laying new flooring or addressing imperfections in existing floors, wood shims are indispensable tools. Placed between joists and subfloors, shims tighten gaps and eliminate squeaks, providing a stable surface for flooring installation.

5. Bathtub Installations

Ensuring a level and stable foundation for bathtubs and shower pans is crucial for preventing water damage and ensuring proper drainage. Wood shims allow installers to adjust pitches and alignments accurately, guaranteeing optimal functionality.

Wood Shims vs. Plastic shims: Choosing The Best Option

The final consideration when working with shims is the choice between wood and plastic variants. While wood shims offer affordability and ease of manipulation, they are susceptible to water absorption and may deteriorate over time. On the other hand, plastic shims boast superior durability and water resistance but come at a higher cost and may be more challenging to shape.


In conclusion, wood shims stand as unsung heroes in the realm of construction and woodworking, offering versatility, affordability, and practicality in equal measure. Whether bridging gaps, leveling surfaces, or fine-tuning installations, these humble wedges play a vital role in achieving precision and perfection in every project.

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