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.

Ultimately, overapplication of stain can compromise the deck's appearance, durability, and longevity. It may result in an uneven finish, with excess stain pooling, dripping, or drying into thick patches. It can also obscure the wood's natural grain and texture, detracting from the desired aesthetic. Moreover, excessive staining may not fully penetrate the wood, leading to poor adhesion and premature wear. Additionally, thick layers of stain are prone to peeling, cracking, and blistering as they struggle to bond with the surface. 

DIY staining or painting is manageable with proper preparation, including safety measures, necessary tools, and adherence to safe weather conditions for application.

Pressure-treated wood contains preservatives that give the material internal protection from rot and pests. Untreated lumber won’t last more than a few years unless you choose a more expensive wood, like cedar, that naturally stands up well to moisture. Composite decking can outlast wood but is more expensive and doesn’t look as natural. Keep in mind that you’ll need to seal any exterior wood product to protect it from the elements and other forms of external damage.