If you own a home in Trail, Rossland, or the surrounding West Kootenay, you've probably met the same problems: a door that drags on the floor, a window that rattles in wind, or a kitchen cabinet that wobbles. You don't always need an expensive contractor to fix these. Small wedges called shims do most of the heavy lifting. Done right, shimming saves money, preserves old trim, and keeps heat in on cold winter nights.
This article compares the options for shimming, explains what matters when you choose a method, and gives practical do-it-yourself guidance tailored to older, budget-conscious houses in a wet, cold mountain climate.
3 Key Factors When Choosing a Shimming Method for Older Homes
Not all shims are equal. Picking the wrong type or using them incorrectly can make a repair temporary, create rot or thermal bridging, or give you misaligned doors and windows that need reworking later. Think about these three factors first:
- Load and location - Is the shim holding a trim piece, a non-structural door jamb, or a window buck that carries loads? Exterior sills and anything touching the ground need rot-resistant materials. Compressibility and long-term stability - Some shims compress over time. Wood will compress and can settle; plastic tends to hold shape. For fine adjustments that must remain stable for years, choose low-compression materials. Moisture and thermal performance - In the Kootenays you get wet winters and freeze-thaw. Metal shims can conduct cold into the house; untreated wood can rot. For exterior or damp locations pick materials that won't degrade.
Think of shims like wedges under a wobbly table leg. If the wedge keeps springing back, the table stays wobbly. If the wedge soaks up water and crumbles, you'll be back to square one. Make the choice to match the problem.
Wooden Shims: Why Carpenters Still Reach for Them
Wooden shims are the most common tool in a carpenter's bag. They come in tapered stacks or single wedges, typically made from softwood or cedar. For many interior tweaks in older homes they are quick, cheap, and effective.
Pros
- Inexpensive and available at any local hardware store. Easy to cut, plane, or snap off to length. You can taper them further with a utility knife. They compress slightly, which can be useful when you want the shim to seat and not let the member move later. Match interior aesthetics if a tiny bit of trimmed shim is left in a trim reveal.
Cons
- Prone to rot in damp environments if not pressure-treated or made of cedar. Can compress or split under sustained load, so not the best for structural shimming. Variable thickness and grain can make fine adjustments harder without stacking multiple pieces.
When to use wood: interior door jambs, non-load-bearing cabinet adjustments, and small framing where moisture isn't an issue. For exterior window sills or bases that sit on masonry, avoid plain untreated wood unless you seal and paint it thoroughly.
How carpenters use wooden shims
Place the shim so the thin end faces the gap you want to close. Tap gently with a hammer while holding the piece in its final position. Once the part is plumb or level, drive a screw through the jamb into the framing just above and below the shim to lock it. Trim the shim flush with a sharp knife, block plane, or oscillating tool.
Plastic and Composite Shims: What They Offer and Where They Fall Short
Plastic or composite shims—made from JELD-WEN window prices polypropylene, nylon, or fiberglass-filled materials—are a modern alternative. They show up in hardware stores as uniform, thin shim packs and adjustable wedge systems.
Advantages
- Low water absorption, so they won't rot or fall apart in damp conditions. Consistent thicknesses for precise stacking and repeatable adjustments. Good compressive strength and long-term stability in many products. Often color-coded for thickness, making quick measurement easy.
Limitations
- Some plastics become brittle in very cold weather. The West Kootenay winters can be cold; choose a product rated for low temperatures. Less forgiving to over-tightening. A hard plastic shim can shear if a screw is driven too close to the edge. They look wrong when a small edge is visible behind trim, although you can conceal them more easily than metal.
In contrast with wood, plastic shims give you precision and durability with less worry about moisture. On the other hand, they can feel less "solid" underfoot if used to correct floor deflection—then you might pair them with structural fixes.
Common uses
Exterior window bucks, door thresholds, and any spot where moisture or insects could damage wood. For older houses where you want a reliable, long-lasting fix, plastic or composite is often the smarter choice.
When Metal Shims, Felt Strips, or Caulk Make Sense
Beyond wood and plastic there are specialized solutions for specific problems. Each has trade-offs that matter in the Kootenay climate.
- Metal shims: Thin stainless or galvanized steel shims are great for fine leveling under machinery or where you need minimal thickness. They carry high loads without compression. In contrast, metal conducts cold, so avoid direct contact between metal shims and exterior assemblies that should remain insulated. Felt or fiber shims: Traditional in older houses to isolate assemblies and absorb vibration. Felt will compress over time and can trap moisture, so it is best used in dry interior locations or inside window frames where it is protected. Caulk or polyurethane foam: Not true shims, but they can fill small gaps for weatherproofing. On the other hand, they don't provide structural support and can make future adjustments harder if you rely on them to carry load.
Similarly, adjustable wedge shims that screw together (sometimes called screw shims or mechanical shims) are useful where you need an adjustable, locked position without stacking thin shims. They cost more, but they provide precise control and are easy to readjust if the house settles.
When to choose metal or felt
Use metal for machinery mounts, fence posts with metal-to-metal contact inside brackets, or where you need ultra-thin but strong spacing. Use felt for historic trim where you want to protect softer wood against hard contact and can inspect it periodically.
Comparing Costs, Lifespan, and Practicality
Type Approx. Cost Expected Lifespan in Kootenay Conditions Best Use Wood shims (softwood) Very low 5-15 years interior; shorter exterior unless sealed Interior doors, trim, quick fixes Composite/plastic shims Low to moderate 15+ years if UV and cold-rated Exterior windows, thresholds, long-term fixes Metal shims Moderate 25+ years (corrosion-resistant types) Heavy loads, machinery, fine adjustments Felt/fiber Low Variable - compresses over time Historic trim, vibration isolationOn price alone, wood wins. In real homes where moisture is present, the small premium for composite pays off over the years. Metal is a specialist choice, not the default.
Practical Step-by-Step: Shimming a Sagging Interior Door
Here's a simple example you can follow with basic tools.
Tools and materials
- Level and combination square Utility knife or small handsaw Packed plastic or cedar shims Power drill and screws (coated) Trim tool or block plane for flush trimming
Steps
Remove the strike plate or any trim that blocks access to the jamb. Open the door and use a level to find where the jamb is out of plumb or the door drags. Loosen the hinge screws slightly so the jamb can move. Insert a shim at the hinge location between the jamb and framing on the side that needs to move. For a high edge that drags, add shims at both top and bottom hinges and adjust until the door clears. Drive longer screws through the jamb into the framing through the shim area to lock the jamb in place. Use coated screws for moisture resistance even inside the house—older homes can be damp. Trim the shim flush to the jamb and reinstall the strike plate. Check operation and adjust as needed.Avoid over-shimming on one hinge only. Spread support across the hinge locations so the jamb bears load evenly. In contrast, using a single over-tightened screw can split the jamb and make the repair worse.
Common Mistakes and How to Avoid Them
- Using shims to hide structural problems: Shims can level a surface, but they won't correct rotted framing or undersized members. If a floor is sagging from joist failure, sister the joist rather than stacking shims. Forgetting to lock the shim: A loose shim will work its way out. Lock it with a screw through the jamb or glue it with construction adhesive if the location won't be adjusted later. Placing shims in exposed exterior gaps: If faced with a large exterior gap, block it first and then use appropriate flashing. Shims alone won't keep water or critters out. Neglecting thermal bridging: Avoid continuous metal shimming across insulated assemblies—on an exterior window, metal can create a cold path that invites condensation.
Choosing the Right Shimming Strategy for Your Situation
For older West Kootenay homes a practical approach balances cost with longevity. Here are reliable rules of thumb.
- Interior, dry locations: Softwood shims work fine. They are cheap and easy. Use longer screws to lock the piece in place and check again in a season. Exterior, damp, or ground-contact areas: Use composite/plastic or stainless shims. Seal any wood near the exterior with paint or flashing. In contrast to wood, composites won't absorb moisture and rot. Load-bearing or precision needs: Use metal or high-strength composite shims, and pair them with structural fasteners. If you're not sure the jamb is framing-level, consult a carpenter before relying on shims alone. Historic trim or vibration isolation: Felt or fiber strips can help, but expect them to compress. Plan for periodic inspection.
On the other hand, if your budget is tight and you want a DIY-first approach, start with inexpensive wooden shims for interior tweaks and upgrade to plastic/composite for anything near the elements. It’s a small upfront cost that avoids rework from rot or cold transmission.
Final practical tip
Shim conservatively and then lock. Little adjustments give better outcomes than over-wedging. Think of shims as "precision packing" rather than brute-force fixes. When you seat the pieces correctly, fasten them in place and trim cleanly, the repair lasts and the house looks like you knew what you were doing.
In short: for most fixes around Trail, Rossland, and the West Kootenay, use wood for quick interior fixes, composite or plastic for exterior and long-term repairs, and metal only where its strengths outweigh its downsides. In contrast to the quick-and-dirty approach, a small investment in the right shim pays out over years in fewer callbacks and less heat loss.