🧱 1. Confirm Structural Support Under Decking
Trex and most composite boards are not load-bearing — your pergola must be anchored into the underlying joists or structural framing.
👉 Inspect and prepare:
Locate the joists beneath your decking where each pergola post will sit.
If the pergola baseplates do not align with joists, install cross blocking between joists using pressure-treated lumber or steel.
Each baseplate must anchor with at least two bolts into solid wood or steel framing for stability.
📏 2. Mark Baseplate Locations
Use your pergola’s layout dimensions to mark exact post base locations on the deck.
Double-check that each mark sits above solid structural support.
Ensure spacing is square and symmetrical before drilling.
🛠️ 3. Drill Pilot Holes Through Decking
Use a spade bit slightly larger than your lag bolt to pre-drill through the Trex board only — not into the joist yet.
This prevents cracking, mushrooming, or deck distortion during bolting.
Remove shavings and apply sealant around hole edges to prevent moisture intrusion.
🔩 4. Anchor Pergola Baseplates to Framing
Use stainless steel lag bolts or structural screws (Simpson Strong-Tie, GRK RSS, etc.) with washers for each post:
Position the Hansø Pergola baseplate over the pre-drilled holes.
Drill pilot holes into the joist or blocking if needed.
Drive lag bolts through the baseplate, composite decking, and into the structural framing.
Tighten securely — but do not overtighten, which could crush the composite or warp the baseplate.
Recommended hardware:
5/16" or 3/8" stainless lag bolts, 4–6” in length
Washers between bolt head and baseplate for even load distribution
🧰 5. Check Level & Adjust
After securing all posts, use a level to ensure vertical alignment.
Add shims under the baseplate if needed.
Proper leveling prevents future stress on louvers, beams, or motors.
🧼 6. Seal Around Bolts
Apply outdoor-grade caulk or sealant around bolt holes and beneath each baseplate to prevent water seepage and deck swelling.
🏗️ 7. Proceed with Pergola Assembly
Once all baseplates are firmly anchored:
Continue with the standard Hansø Pergola assembly, attaching vertical posts, beams, louvers, and accessories per your included manual.
⚠️ Important Safety & Warranty Notes
Never anchor directly into composite boards alone — they will flex or crack over time.
Verify structural framing before installation; consult a contractor or structural engineer if unsure.
For steel framing, use self-tapping structural screws or specialized anchors.
If mounting on deck blocks, contact Hansø Home to confirm warranty compliance.
✅ Optional Add-Ons for Extra Stability
Add Simpson post bases or equivalent hardware beneath Hansø baseplates for increased strength.
In high-wind or seismic areas, consider through-bolting with metal backing plates under the deck for reinforced anchoring.