Composite decking requires a solid foundation, substructure, or subframe to ensure stability. This base is typically composed of posts, beams, joists, and footings. The frame's joists can be built from various materials like composite, plastic, timber, or metal, as long as the base can support the deck's weight without shifting. A professional deck builder might recommend installing the frame on a solid concrete base for added durability. The final design and materials for the substructure will depend on your budget, the type of deck, and environmental conditions.

Always sand a deck before repainting so the wood is smooth and ready for paint. While you do not need to fully remove paint before repainting, sanding helps remove any areas with weather and sun damage. Sanding also helps remove chipped or flaking paint and opens the wood pores to improve paint adhesion.

While experienced DIYers may take on the challenge, hiring a licensed professional is often the best route, especially for larger or elevated structures. A local deck contractor is typically the best pro for the job, as they have specialized experience and are knowledgeable about local building codes, ensuring your deck is built safely and designed to last. Other professionals who can build a deck include general contractors and carpenters, who may be more readily available in some regions.

The cost to repair a deck is between $900 and $3,500, depending on the cause and extent of the damage. For example, fixing a sinking deck caused by pest damage can cost between $200 and $600, while replacing sinking boards costs between $500 and $4,000.