In most cases, sanding an old deck before staining it is necessary to achieve a decent finish. If your old deck has a relatively new stain finish on it and you're only doing touch-ups, you can generally skip the sanding part. However, if your goal is to make the deck look and function better, sanding first is a must. 

If you want to make a deck cleaner from products already in your home, there are various options. The most common is to use a gentle blend of 1 gallon of warm water and 2 tablespoons of ammonia-free dish soap. You can also mix water with distilled vinegar. Sprinkling on some baking soda can help to remove mold and mildew. You can add oxygen bleach (but never damaging chlorine bleach) to the water and ammonia-free dish soap solution for something a bit stronger. 

Yes, deck pier blocks can be used as an alternative to traditional deck footings, especially for smaller or low-to-the-ground decks. Unlike poured concrete and buried post footings, deck blocks do not require digging or pouring. However, their use is dependent on local building codes. Some areas, particularly those prone to high winds, earthquakes, or hurricanes, may not permit the use of deck pier blocks. It is essential to consult your local building codes before choosing them for your deck project.

Yes, transforming a deck into a sunroom is an absolute possibility. Building a sunroom involves framing in the deck area with walls, adding windows, and affixing a roof. This project is not an easy task, but it does provide a stylish addition to your house. Not all deck designs support this type of renovation project, so consult a professional deck builder before beginning.