Before installing a deck, you must build a base for the deck to rest upon, often made of compacted soil or gravel. While gravel is an optional material, it helps with drainage. Some contractors also recommend installing a weed control membrane, which helps provide a solid foundation for the frame. In the case of an elevated deck, a pro will often lay down a concrete slab as a foundation. 

A wood deck requires annual cleaning and regular inspections for loose or broken boards, nails, and screws. It should be refinished by applying a stain or sealer every two to three years to protect the wood from water damage, rot, mildew, and sun fading. The exact frequency can depend on the climate and the deck's exposure to sun and moisture. If your deck is painted, it will need repainting approximately every 10 years. Signs that your deck needs refinishing include faded, splintering, or warping boards.

It is recommended to clean your deck once or twice a year to prevent the accumulation of dirt, debris, mold, and mildew. The ideal times for cleaning are in the spring and fall. A spring cleaning removes grime that has built up over the winter, preparing your deck for summer use. A fall cleaning washes away messes from summer activities, preventing them from setting into the wood over the winter. The exact frequency can depend on factors such as how often the deck is used, its exposure to pollen, and whether salt was used on it during the winter. Regular cleaning helps protect the wood and its finish from damage.

Yes, it is possible to add an under-deck drainage system to an existing deck by retrofitting it to the structure. This process may require some prep work. For example, many drainage systems are installed on top of the deck joists, which would require you to remove the decking boards and railings first. To avoid this, you could opt for a below-the-joist drainage system. For best results and to ensure proper installation, it is recommended to consult a professional. A pro can inspect your deck, make any necessary repairs, and then install the drainage system correctly.