Furring Strips & Shims
2026 Furring Strips & Shims Buying Guide (2026)
Furring strips and shims are the unsung heroes of construction — small, inexpensive pieces of wood that make everything else line up perfectly. Furring strips create flat nailing surfaces over masonry, uneven walls, and ceilings. Shims level doors, windows, cabinets, and framing. Despite their simplicity, choosing the wrong material or size can compromise your finished project. This guide covers the essentials.
Key Takeaways
- Furring strips and shims are the unsung heroes of construction — small, inexpensive pieces of wood that make everything else line up perfectly.
- Furring strips create flat nailing surfaces over masonry, uneven walls, and ceilings.
- Shims level doors, windows, cabinets, and framing.
- Furring strip dimensions: 1×2 and 1×3 are most common
- Material: Softwood (pine, spruce), pressure-treated, or composite
What to Look For
- Furring strip dimensions: 1×2 and 1×3 are most common
- Material: Softwood (pine, spruce), pressure-treated, or composite
- Straightness: Sight down the length — crooked strips create crooked walls
- Shim material: Wood (cedar or pine), plastic, or composite
- Application: Interior vs. exterior (exterior requires pressure-treated or rot-resistant)
Species Comparison
Pine and spruce are the standard furring strip species — affordable and widely available. Pressure-treated pine is required for exterior applications and any contact with masonry or concrete. Cedar shims are the traditional choice — lightweight, compressible, and naturally moisture-resistant. Plastic composite shims are gaining popularity for their consistency, moisture immunity, and the fact that they do not compress over time like wood. For hat-channel metal furring, steel or aluminum options eliminate wood moisture concerns entirely.
Size Guide
Furring strips: 1×2 (3/4" × 1-1/2" actual) and 1×3 (3/4" × 2-1/2" actual) in 8' lengths. Thinner furring: 1/4" × 1-1/2" lattice strips for minimal shimming. Standard shims: 1-1/2" wide, 8"–12" long, tapered from 3/8" to a point. Horseshoe shims: 1-1/2" × 2" with a U-slot for bolt alignment. Bundle sizes: Shims sold in packs of 12–42 pieces; furring strips sold individually.
Grade Guide
Utility grade is standard for furring strips — some knots and minor warp are acceptable since strips are fastened flat to a surface. Premium or Select grade furring strips have fewer defects and are recommended for visible applications like ceiling plank installations. Shims are not formally graded but should be free of knots at the tapered tip to prevent snapping during installation. Cedar shims are naturally more consistent than pine.
Budget Breakdown
Budget: Pine furring strips at $1.00–$2.00 each (1×2×8'). Mid-range: Pressure-treated furring strips at $2.00–$3.50 each. Premium: Composite furring strips or stainless steel hat channel at $3.00–$6.00 per 8' piece. Cedar shims: $4.00–$8.00 per 12-pack. Composite shims: $5.00–$10.00 per pack. For a typical room of paneling, furring costs $20–$50 total.
Common Mistakes to Avoid
- Using untreated furring strips against concrete or masonry, where moisture causes rot
- Not checking strips for straightness before purchase — warped strips create uneven surfaces
- Stacking shims instead of using a single tapered shim pair for precise adjustment
- Forgetting to score and snap shims flush — leaving protruding shims behind trim
- Spacing furring strips too far apart, causing paneling or drywall to flex between them
Pre-Purchase Checklist
- Determine if pressure-treated material is required (masonry contact, exterior use)
- Select furring strip size based on the depth of shimming needed
- Hand-select straight strips — sight down the narrow edge
- Buy enough shims for all door, window, and cabinet installations
- Choose cedar or composite shims for moisture-prone areas
- Plan furring strip spacing: 16" o.c. for paneling, 24" for drywall on flat walls
Frequently Asked Questions
1×3 strips are preferred for ceiling applications — they provide a wider nailing surface. Space them 16" on center perpendicular to your plank direction.
Yes. Any furring strip in contact with concrete or masonry must be pressure-treated to prevent moisture-related rot.
Cedar shims compress slightly for a snug fit and are easy to score and snap. Plastic shims resist moisture and do not compress over time, making them ideal for cabinets and wet areas.
Insert opposing tapered shims from each side of the gap between the jamb and framing. Slide them together until snug, check plumb with a level, then fasten through the shims into the framing.