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.

It is possible to pressure wash your deck, but it’s usually best to leave the work to a professional for two main reasons. First, power washers are expensive, and you can avoid high upfront costs by hiring a deck washing pro instead. Second, you must be careful to use the correct setting to avoid damaging your deck material. You can only clean soft woods like pine with a wide spray and a low pressure; otherwise, the water will leave unpleasant marks on your deck. Hard woods, composite material, and metal can stand up to increasingly higher water pressures.

There are ways to clean your deck to help maintain a clean appearance. You can easily remove surface-level dirt and grime by wetting your deck with a hose and doing a quick scrub with store-bought deck cleaner monthly. 

However, investing in professional deck cleaning services near you at least twice a year is worth it. This service saves you time and ensures that your deck will avoid accidentally becoming scratched by blasting the pressure washer at the wrong angle.

The best way to sand a deck is by cleaning it, sanding the boards and stairs with 60- or 80-grit sandpaper, and sanding the railings and posts with 80-grit sandpaper. You should sand in the direction of the wood grain to avoid damaging the timber. When sanding your deck, use medium pressure and aim for an even sand. Pressing too hard with a sander can damage decks, as most are softwoods.