Local building codes don’t specify the number of steps a deck can have before a railing is required, mainly because stair height varies widely. Most areas require decks 30 inches or higher to have a railing. While not exact, that roughly equates to four to seven steps.

For a 12x20-foot (240-square-foot) deck, you can expect to pay between $7,200 and $14,400. This cost is based on a general price of $30 to $60 per square foot. The final price will depend on factors such as the decking material, design complexity, deck type, location, and local labor costs. Keep in mind that add-ons will increase the total; for example, adding an under-deck drainage system to a deck of this size could cost an additional $7,700.

Both aluminum and composite decking materials are environmentally friendly, with aluminum decking coming in as the most eco-friendly option. 

Though composite decking helps remove plastics from landfills, recycles wood, and lasts longer than traditional wood decks, it’s not recyclable and only lasts for 25 to 30 years on average. Aluminum can last well over 30 years and is almost always recyclable.

Most building codes require that railing spindles (also known as balusters) on decks or stairs be spaced no more than four inches apart. This safety standard is often called the '4-inch sphere rule,' which means a sphere with a 4-inch diameter should not be able to pass through the opening between balusters. This rule is in place to prevent small children and pets from slipping through the railing. For the same reason, the space between the bottom rail and the deck or floor surface should also be no more than four inches. As a general guideline, professionals often install three balusters per foot of railing. However, since specific requirements can vary by location, it is essential to check your local building codes to ensure compliance before starting your project.