6 Best Wood Shims For Temporary Leveling Pros Use

Whether framing a deck, installing door jambs, or setting a heavy beam, the difference between a project that lasts and one that fails often comes down to a few thin pieces of wood. Cheap, crumbling shims can cause a structure to settle, leading to cracked drywall or binding doors within months. Relying on professional-grade materials ensures that the temporary alignment holds long enough for the final fasteners to take the load. Choosing the right shim isn’t just about price; it is about moisture resistance, compression strength, and how cleanly the material breaks under pressure.

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Nelson Wood Shims: The Go-To for Most Jobs

Nelson shims have earned their reputation as the industry standard for interior finish work. Their consistent thickness and predictable taper make them the first choice for hanging cabinets or leveling interior door frames where precision is non-negotiable.

When working on a tight deadline, the last thing needed is a bundle of shims with varying widths or inconsistent grain. Nelson shims maintain a reliable geometry that speeds up the leveling process significantly. They provide enough friction to hold their position without needing excessive adhesive during the initial fit-up.

For the average interior project, these are the reliable baseline. Do not expect them to perform well in high-humidity zones or exterior applications, as their pine composition lacks natural rot resistance.

Trim-Pak Cedar Shims: Best for Outdoor Use

Cedar is the preferred material for any application exposed to the elements. These shims offer a natural defense against rot and decay, which is critical when leveling exterior trim or pressure-treated components.

When exterior flashing or window trim isn’t perfectly plumb, moisture can find a way behind the siding, leading to rot and structural degradation. Using a non-rot-resistant shim in these zones is a shortcut to a call-back. Cedar shims ensure that even if incidental moisture reaches the gap, the shims won’t turn into a spongy mess.

Always keep a bundle of cedar shims in the truck for siding jobs or deck building. While they cost slightly more than standard pine, the long-term protection of the building envelope justifies the expense.

Beddar Wood Shims: Clean Snaps No Splinters

The frustration of a shim that splinters unevenly when being “snapped off” is a universal experience on the job site. Beddar wood shims are engineered to break cleanly, saving time on cleanup and preventing unsightly jagged edges in visible areas.

A clean snap allows the shim to sit flush against the substrate without leaving a protruding “nub” that must be painstakingly chiseled away. This feature is especially valuable when installing baseboards or window casings where the gap is narrow and access for a utility knife is limited.

Efficiency on the job site is cumulative. If one saves five seconds per shim by not having to shave down a rough break, those savings add up over the course of a multi-room renovation.

Go-Shims Tapered Shims: For Fine Adjustments

Fine adjustments require a shim with a subtle, consistent taper that allows for micro-movements. Go-Shims are designed for the high-end finish carpenter who needs to dial in a perfect reveal on a door or a perfectly flat transition between floor surfaces.

These shims shine when the gap being closed is irregular or requires multiple thin adjustments. Because their taper is so precise, they allow for a smoother transition when stacked, reducing the risk of “stepping” that can occur with poorly milled materials.

They are less about bulk structural support and more about the aesthetics of the final fit. Use these when the trim work needs to look like a seamless extension of the architecture.

Big L Hardwood Shims: For Heavy-Duty Leveling

When the job involves heavy loads—such as leveling a support post, a heavy appliance, or a structural cabinet run—softwood shims often compress and fail. Big L hardwood shims provide the density required to maintain a gap under significant weight.

Hardwood shims possess a much higher compression strength than pine or cedar. They do not “crush” as easily, which keeps the structure stable once the primary fasteners are torqued down. This is the only acceptable choice when dealing with concentrated point loads.

Be aware that hardwood is harder to snap. Keep a sharp chisel or a stiff-bladed putty knife handy to score the back of the shim if a clean break is required in a tight space.

Builder’s Best Pine Shims: Your Top Budget Pick

For rough framing or hidden leveling where extreme precision is secondary to volume, Builder’s Best Pine is the contractor’s bulk choice. They are inexpensive and get the job done when large numbers of shims are required for a big project.

Use these for backing out studs, leveling joists, or any application where the shims will be covered by drywall or flooring. They are not intended for fine trim or exterior exposure, but they offer the necessary utility for rough carpentry.

Don’t use these for high-stakes leveling or exterior finish. Keep them for the “invisible” work where the price-per-shim matters more than the finish quality.

Pine vs. Cedar vs. Hardwood: Which Shim to Use

The choice of material dictates the lifespan and performance of the repair. Using the wrong wood type can lead to structural failure or premature rot.

• Pine: Best for interior, low-load, hidden applications. Cost-effective and widely available.
• Cedar: Essential for exterior, high-moisture, or pest-prone areas. Naturally rot-resistant.
• Hardwood: Required for load-bearing situations where compression could lead to settling.

Always match the shim to the environment and the load. A hardwood shim will hold a heavy beam steady for years, while a pine shim might compress and allow the beam to sag over time.

How to Properly Stack Shims for Stable Leveling

Stacking shims requires a “crossed” approach to ensure stability and prevent sliding. Always slide two tapered shims against each other from opposite directions to create a flat, parallel surface.

If one simply stacks shims in the same direction, the stack will be wedge-shaped rather than flat. This creates an unstable base that can cause the supported object to shift or “walk” when weight is applied.

For tall gaps, use a square piece of plywood or blocking as a base and then shim the final adjustment. Never stack more than three shims high without securing them together with adhesive or a fastener to prevent lateral movement.

Understanding Shim Load Limits for Jobsite Safety

Every shim has a breaking point, and overestimating that capacity leads to structural issues. Wood shims are meant for alignment, not for supporting the full weight of a structural load-bearing member indefinitely.

When shimming a post, the shim must be fully supported by the foundation or beam beneath it. If a shim is hanging off the edge of a plate, the cantilevered portion will snap under load, leading to a loss of the leveling work.

Always aim for full surface contact between the shim and the substrate. If the gap is too large for standard shims, frame in a proper blocking piece rather than attempting to stack a dozen shims to reach the desired height.

Temporary vs. Permanent Shimming: Know the Rules

There is a significant difference between temporary shimming for alignment and permanent support for a structure. Temporary shims are meant to hold a piece in place until it is mechanically fastened, at which point the shim should ideally be encased or replaced by a structural shim if necessary.

When permanently shimming a door frame, ensure the shims are placed at the hinge locations and the strike plate. Leaving a door frame shimmed only at the top or bottom leads to sagging over time.

Never leave large, unsecured voids behind siding or trim. If the shims are holding up a component that will be under constant stress, ensure they are checked for stability periodically during the construction process.

Selecting the right shim is a small detail that carries significant weight in the final quality of any construction project. Whether the requirement is for high-density hardwood to support a heavy beam or rot-resistant cedar for exterior trim, understanding the material properties will prevent common failures. Invest in quality shims, use them with proper stacking techniques, and the structure will remain true long after the project is signed off.