Understanding Cumaru Decking Requirements
Cumaru is a tropical hardwood known for its exceptional density and strength.
This density also means Cumaru boards are heavier than many other decking materials. The existing frame must be robust enough to support this additional weight, not just for the decking itself, but also for live loads like furniture, people, and snow accumulation. (S1)
Assessing Your Existing Deck Frame's Condition
Before considering frame reuse, a thorough inspection is essential. Look for any signs of rot, insect damage, or excessive warping in the joists, beams, and support posts. Pay close attention to areas where the frame meets the ground, ledger board connections, and any points exposed to standing water.
Even if the frame appears sound, check for fasteners that are corroded or pulling away. Joists should be level and consistently spaced. Any compromised structural elements will need repair or replacement to ensure the safety and longevity of your new Cumaru deck. A qualified deck builder or structural engineer can provide a professional assessment.
Verify that the existing frame is securely attached to your home's structure. The ledger board, which connects the deck to the house, must be properly flashed and fastened to prevent water intrusion and ensure structural stability. Any issues here could lead to significant problems down the line, regardless of the new decking material.
Checking Joist Spacing for Cumaru Decking
Cumaru decking is typically available in standard profiles such as 1"x6" (actual 3/4" x 5.5") and 5/4"x6" (actual 1" x 5.5"). Wider joist spacing can lead to excessive deflection or movement of the boards, potentially causing fasteners to loosen or the decking to cup over time.
This is a crucial step for preventing issues with your Cumaru decking's performance and appearance over its long lifespan. (S1)
Ventilation and Drainage Considerations
Proper ventilation beneath your deck is vital for any decking material, and especially for dense hardwoods like Cumaru. Adequate airflow helps prevent moisture buildup, which can lead to mold, mildew, and potential issues for both the decking and the frame.
Ensure there is sufficient clearance between the ground and the underside of the deck, and that no obstructions block airflow. If your existing frame is low to the ground or has poor ventilation, consider ways to improve it during the resurfacing project. Good drainage away from the deck foundation is also essential to protect the frame from prolonged moisture exposure.
Worked Example: Joist Spacing Adjustment
You plan to install 1"x6" Cumaru decking.
Always consult with a professional to confirm the best approach for your specific structure.
Before you order
- Has a qualified professional inspected the entire deck frame for structural integrity?
- Are there any signs of rot, insect damage, or excessive warping in the joists, beams, or posts?
- Are all fasteners secure and free from significant corrosion?
- Is the ledger board properly attached and flashed to the house?
- What is the current on-center spacing of your deck joists?
- Is there adequate ventilation beneath the deck to prevent moisture buildup?
- Does the ground beneath the deck slope away from the foundation for proper drainage?
- Are all local building codes and regulations for deck resurfacing being met?
Confirm installation details, approved uses and warranty terms in the current instructions for the exact product and profile. Your installer should verify the substrate, structure and applicable project requirements.
Questions to help you decide
How do I know if my existing deck frame is strong enough for Cumaru?
Due to Cumaru's density and weight, a professional inspection is recommended. They can assess the condition of the joists, beams, and posts, and confirm if the frame meets current load-bearing requirements for the heavier decking material and anticipated live loads.
What happens if my joists are spaced too far apart for Cumaru decking?
It is generally advised to add intermediate joists or blocking to reduce the span and provide adequate support for the dense hardwood.
Can I install Cumaru decking directly over my old deck boards?
No, Cumaru decking should not be installed directly over existing deck boards. The old decking must be removed to expose the frame for inspection and to allow for proper fastening and ventilation of the new Cumaru boards.
Ready to Transform Your Deck with Cumaru?
Request a material quote with your project dimensions, desired Cumaru profile, and ZIP code. We can confirm current availability and service options for your Cumaru decking project. Consider exploring our full range of decking options, including other hardwoods like Ipe, or low-maintenance composite and PVC decking if frame modifications are extensive.
Request a material quote →