Can you install composite decking over the wooden deck?
Outdoor living spaces are becoming increasingly popular. Often, wooden decks that have been in use for many years face the choice of demolition and reconstruction or renovation and upgrading. Composite deck tiles have become the preferred choice for deck construction and upgrades. Many homeowners face the same dilemma: Can I install composite decking over the wooden deck?
This article will analyze the feasibility of installing composite decking on a wooden deck. You can develop the optimal deck renovation plan based on your specific circumstances.
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Table of Contents
How to Assess Whether Composite Decking Can Be Installed on An Existing Wooden Deck?
Yes, composite decking can be installed over an existing wooden deck. However, this requires ensuring that the existing structure is stable and reliable. Before construction begins, it is essential to thoroughly inspect the wooden deck. Pay particular attention to the deck’s framework, posts, and joists for signs of rot or decay.
If the existing structure is in good condition, the deck boards can be replaced with composite deck boards. This approach saves time and reduces costs. If the wooden deck is in poor condition, it is recommended to thoroughly repair or replace the deck framework.
Inspect Structural Integrity
Before installing composite deck boards, you must first inspect the existing deck structure. If the wooden deck shows signs of cracking, rot, or instability, it is recommended to remove and replace it. This is because it may affect the stability and service life of the newly installed composite decking boards. You can use the following methods for inspection:
- Carefully inspect the joists, beams, and posts. Look for signs of rot, decay, and structural damage.
- Use a screwdriver or ice pick to test the hardness of the wood. Areas that are easily penetrated indicate that the wood has softened.
- Pay special attention to areas near the ground and locations with poor drainage. These areas are most prone to rot.
- Inspect connection points and load-bearing areas. Ensure there are no structural cracks or deformations.
Check The Flatness and Slope of The Wooden Deck Surface
The existing deck should be level and structurally sound to support the new composite deck. Significant unevenness can affect the installation of the new deck. You can use a level to check the flatness of the deck surface. Additionally, assess the drainage slope of the deck. Check for areas with standing water. These areas may indicate structural issues.
Check That The Joists Meet Requirements
Ensure the joist spacing is correct. Composite deck joists typically have a center-to-center spacing of 16 inches. Measure the existing joist center-to-center distance. If the spacing is incorrect, you may need to add additional joists. Additionally, design according to the installation instructions for the composite deck material. Different composite deck products and series may have specific requirements.
Consider How Long The Wooden Deck has been in Use
Even if the overall structure of the wooden deck is intact, it does not necessarily mean it is suitable for continued use. Wood ages over time with use. Therefore, wooden decks that have been in use for over 10 years are not suitable for such installations. It is recommended to install composite decking on decks that have been in use for less than 7 years. This ensures better deck performance and longevity.
How to Install Composite Decking over The Wooden Deck?
After completing the above inspections, you can proceed with construction on the wooden deck. Below are the correct installation procedures and technical points.
- Remove Obstacles: First, remove all furniture, decorations, and equipment from the deck. Dismantle the railing system. Reinstall and adjust the railings after installation is complete. If the existing deck boards are severely damaged, they should be removed.
- Clean and Repair the Deck Surface: Thoroughly clean the existing deck surface. Remove dirt, mold, and loose materials. Additionally, repair or replace loose or damaged boards. Ensure all fasteners are securely fastened and flush with the surface.
- Structural Reinforcement: Reinforce structurally weak areas based on the inspection assessment results. If necessary, add additional joists to meet recommended spacing standards. Additionally, it is recommended to apply wood preservative to all wood cuts and exposed surfaces.
- Install a Moisture Barrier: Use professional moisture barrier film or joist tape. Ensure complete coverage of all surfaces, especially at seams and edges.
- Install Composite Deck Boards: Install strictly according to the manufacturer’s guidelines. Generally, composite decks are recommended to use a dedicated hidden fastening system. Ensure appropriate gaps between boards to accommodate thermal expansion and contraction. Additionally, install from the perimeter inward in stages. This ensures neat alignment.
- Inspection and Adjustment: The final step is to check the security of all fasteners. Inspect the drainage system to ensure proper drainage with no standing water. Then adjust or replace the railing system to accommodate the new height.
What are The Risks of Installing Composite Decking over a Wooden Deck?
Installing composite decking over a wooden deck is feasible. However, this method carries some potential risks. Therefore, you must carefully consider and mitigate these issues.
Drainage Issues
Composite wood decking itself has excellent waterproof and moisture-resistant properties. However, between the two layers of decking, moisture can easily accumulate and is difficult to evaporate. This damp environment accelerates wood rot. Using a moisture barrier or joist tape cannot completely resolve this issue. Moisture may still enter through edge gaps or fastener holes.
Load-bearing Capacity
Generally, composite deck materials are heavier than natural wood. This imposes a significant additional load on the existing structure. Therefore, it is essential to thoroughly assess the load-bearing capacity of the existing deck.
Some types of wood have insufficient load-bearing capacity. Additional weight may cause structural deformation or even collapse. In addition, if the original deck has been in use for more than 10 years, direct covering installation is not recommended.
Risk of Height Increase
Covering a wooden deck with composite wood decking may elevate the deck surface. This may pose the following risks:
- Incompatibility with doorways, stairs, and railings in terms of height.
- The need to adjust or replace the railing system to meet safety standards.
- Possible violation of local building code restrictions on deck height.
These issues must be thoroughly considered during design to mitigate risks.
Maintenance and Warranty
When the underlying structure requires maintenance, the composite deck on the upper layer must first be removed. This effectively increases long-term maintenance costs and workload. In addition, many composite deck manufacturers do not offer warranties for this type of installation. This is because it does not comply with their recommended installation methods.
Conclusion
Installing composite decking over the wooden deck is both simple and cost-effective. It is also faster than completely re-laying the entire deck. Composite decking materials offer superior dimensional stability and corrosion resistance compared to natural wood. These characteristics make them suitable for a variety of installation environments.
Before starting construction, it is crucial to ensure the structural integrity of the existing wooden deck. Therefore, please inspect the wooden deck and its framework. You may also seek a professional contractor for assessment and installation. If you have further questions, please contact EVODEK’s professional team. We will answer all your questions about composite decking.
FAQ
Should I Use Hidden Fasteners or Surface Screws?
Hidden fasteners are more suitable for this installation method. They avoid drilling holes in the surface of the boards, reducing the risk of water penetration. Additionally, they provide more uniform expansion and contraction space. However, hidden fasteners require a higher level of surface flatness. You must strictly follow the manufacturer’s guidelines for installation.
How Much Will Installing Composite Decking on a Wooden Deck Raise The Deck Height?
This installation method typically raises the deck by 1.5–2 inches. Therefore, you will need to adjust facilities such as railing systems and stairs. For example, the new deck height may cause existing railings to fall below safety standards, requiring them to be raised.
Stairs must be re-adjusted for step height and joists to ensure compliance with safety regulations. In addition, you should also check the height difference between the doorway and the deck. Avoid the risk of tripping or rainwater flooding.
Is It Suitable to Install Composite Decking over The Wooden Deck in Humid Regions?
Humid regions pose higher risks and require extra caution. A damp environment accelerates the retention of moisture between deck boards. This can easily lead to rot in the lower layers. Therefore, waterproofing measures must be prioritized. Composite joists should be used instead of wooden structures. You can also add drainage holes or ventilation designs. Additionally, regular inspections and maintenance are essential.
How Should Maintenance be Conducted After Covering Installation?
Maintenance focuses on preventing moisture retention and inspecting hidden issues. Regularly clean the gaps between boards to ensure proper drainage. Annually inspect edges and corners for signs of moisture accumulation. If there is local subsidence or loosening, the condition of the underlying layer should be checked immediately.
What is The Cost Difference Between Covering Installation and Complete Replacement?
Covering installation typically saves 30%-50% in costs compared to complete replacement. However, long-term maintenance costs and the deck’s lifespan must be considered. If the underlying structure has issues, repair costs may be higher. Completely replaced composite deck boards typically also offer better durability.
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