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.

Although composite decking is extremely durable, it’s also susceptible to extreme heat. Prolonged exposure to sunlight can cause fading, warping, and cracking. Composite also retains heat more than wood, which makes it dangerous to walk on in the summer. You can help prevent heat damage by only building with composite in shaded areas or using rugs to cover the hottest spots.

Whether you need a permit depends on the deck design and local regulations. Most areas mandate a building permit if the deck is over a specific height or if it's attached to a pre-existing structure. Shorter, freestanding decks may not require a permit, but you should check with local zoning ordinances and your homeowners association for specifics.

No, you don’t need a permit to repair and replace a few boards on an existing deck. However, if you’re making structural changes to the deck or tearing down the old one and building a new one, you will likely need a permit. Check with your local municipality for the regulations and rules in your area, or ask a local contractor who builds decks for advice.