⚠️ Important Notice
A pergola is a structural system, not a lightweight accessory.
Without concrete anchoring, your deck itself becomes the foundation — meaning its substructure must be capable of supporting the total static and wind load.
Before installation:
Verify that your deck framing meets or exceeds building code standards.
Consult a qualified contractor or structural engineer if unsure about load capacity.
📏 Typical Load Reference
Model | Weight (Approx.) | Recommended Deck Framing |
Pro+ 10×10 | ~300 kg / 660 lb | Reinforced joist grid under each post |
Pro+ 10×13 | ~350 kg / 770 lb | Reinforced joist grid under each post |
Pro+ 13×13 | ~400 kg / 880 lb | Reinforced double beam under posts |
Pro+ 13×19 (Double Bay) | ~550 kg / 1,210 lb | Heavy-duty joist framing + triple beam |
💡 Tip: Always assume 1.5× the pergola’s static weight to account for wind uplift and live loads.
🧱 Mounting Concept
Your pergola’s baseplates will bolt directly into reinforced substructure blocking located under your decking boards.
These blocks act as the “virtual concrete footers” — transferring all loads into the joist framework.
🧩 Step-by-Step Installation (No Concrete Footer)
1️⃣ Identify Joist Layout
Use a stud finder or remove a small section of decking to locate joists.
Confirm joist spacing (typically 16″ or 24″ on center).
Mark the post positions using your Post-to-Post Measurement Guide.
2️⃣ Add Reinforcement Blocking
Install solid blocking or bridging between joists under each pergola post location.
Use 4×6″ or 6×6″ pressure-treated lumber secured with lag bolts or joist hangers.
Create a continuous load path — joist → blocking → beam → post.
For double-bay models, ensure reinforcement spans both post locations.
💡 Tip: Blocking should extend across at least two joists per post for proper load spread.
3️⃣ Drill Through Deck Boards
Once blocking is in place, pre-drill holes matching the baseplate anchor slots.
Use M10–M12 bolts (3/8″–½″) or equivalent lag screws.
Tighten snugly but avoid over-torquing to prevent deck compression.
4️⃣ Apply Sealant
Apply exterior-grade silicone or polyurethane sealant around bolt holes.
This prevents moisture penetration into the deck framing.
5️⃣ Mount the Pergola
Align each baseplate according to the Post-to-Post Measurement Chart.
Verify that all baseplates are level and aligned diagonally.
Secure bolts fully once alignment is confirmed.
⚙️ Recommended Hardware
Component | Specification | Notes |
Anchor Bolts | M10–M12 (3/8″–½″) x 4 per baseplate | Stainless or galvanized |
Blocking Material | 4×6″ or 6×6″ treated lumber | Extend across two joists |
Fasteners | Structural screws or lag bolts | e.g., Simpson Strong-Tie SDS |
Sealant | Exterior-grade silicone / polyurethane | Around bolt penetrations |
Washers | Large flat washers | Distribute bolt pressure |
🧰 Optional Reinforcement Techniques
Under-Deck Support Posts
For heavy pergolas (13×13 or 13×19), you can add 4×4″ or 6×6″ support posts beneath the deck tied into footings or concrete pads for added strength.
Steel Post Brackets or Plates
Add steel reinforcement plates under the deck surface to increase load distribution.
Double Joists
Sister two joists together under each post location for better load resistance.
🚫 Avoid These Mistakes
Do not anchor into deck boards only — they cannot support the load.
Do not install over hollow composite planks without structural backing.
Do not rely on deck screws or non-structural fasteners.
Avoid mounting on floating decks (not anchored to the ground).
📏 Height & Stability Considerations
For elevated decks above 24″, lateral sway may be amplified.
Use lateral bracing or cable ties between posts for additional rigidity.
Consider using shorter post kits or trimming post length for lower profiles if the deck is elevated.
🪜 Maintenance Tips
Recheck bolt tension every 6–12 months.
Inspect for any deck flex or movement after strong winds.
Reseal around baseplates annually to maintain weatherproofing.
⚠️ Warranty Reminder
Installing a pergola on a wooden deck without concrete anchoring is considered a non-standard installation method.
Hanso recommends confirming that:
The deck structure can support the pergola’s full static and dynamic load, and
Anchors are attached to load-bearing framing members, not surface boards.
Failure to meet these requirements may void structural warranty coverage due to improper foundation.