Yes, but ensuring the deck has a solid foundation with adequate footings is critical before building, as the weight of a sunroom will put significant pressure on the structure below. Even if your deck is properly constructed, it may not be able to handle the extra weight. While some basic, lightweight, prefabricated sunrooms can sit on a deck with a strong existing foundation without additional supports, in many cases, the foundation and joists will need reinforcement. It is always best to have a structural engineer perform an inspection to evaluate the deck's quality and structural integrity. A professional can help you decide if reinforcement is sufficient or if it's better to tear down the deck and start over.

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.

There are approximately 5.33 board feet in a 2x4. You can use the board foot calculator in this article to easily find the answer. A 2x4 is 2 inches of thickness by 4 inches of width, so you need to find the length, with 8 feet being the most common. You’d use the calculator here to multiply 2 times 4 times 8, and then divide by 12, arriving at a total of 5.33 board feet. 

The time to build a vinyl deck varies based on factors like size, the complexity of the design, and weather conditions. Generally, a straightforward project might take a few days to a couple of weeks for preparation, installation, and any necessary inspections. However, larger or more intricate designs may extend the timeline. Timely acquisition of permits, efficient planning, and coordination with contractors will all help to make the construction process as smooth and quick as possible.