What are timber bolts?
Timber bolts are round-head structural bolts made for fastening heavy wood members. Under the head they typically include anti-rotation lugs/nibs (or a small bearing ring) that bite into the timber so the bolt won’t spin while you tighten the nut. The smooth, low-snag head protects surfaces and hardware in public-facing installs.
Why choose timber bolts
- One-side installation — under-head lugs lock into the wood so you can tighten from the nut side only.
- Smooth, robust head — rounded profile resists snagging and looks clean on exposed structures.
- Built for wood structures — long shank lengths and washer/nut compatibility for high clamp loads.
- Outdoor-ready options — hot-dip galvanized and stainless selections for weather exposure.
Materials & finishes for timber bolts
- Carbon steel for general structural use.
- Hot-dip galvanized steel for thick, durable corrosion protection in exterior work.
- Stainless steel (304 / 18-8) for broad corrosion resistance; 316 for coastal/chloride environments.
- Pair with matching nuts and washers (same material/finish) to maintain corrosion compatibility.
Common applications for timber bolts
- Timber framing, pergolas, pavilions, boardwalks, and bridges
- Utility and site structures, outdoor furniture, and guardrails
- Post-and-beam connections and heavy landscaping timbers
- Playgrounds and public installations where a smooth head is preferred
How to size and specify timber bolts
Order by diameter × thread × length (e.g., 1/2″-13 × 8″). Length is measured from under the head to the end of the bolt. Choose the material/finish for the environment and pair with appropriate flat washers, lock washers, and nuts to meet design loads.
Installation tips for timber bolts
- Drill a snug, straight hole; tap the head to seat the lugs before final torque.
- Use large-OD flat washers to distribute load and protect wood fibers.
- Where vibration is expected, add lock washers or a prevailing-torque/locknut.
- For exterior assemblies, keep materials matched (e.g., galvanized bolt + galvanized hardware).