Yes, balusters are required on stairs to ensure safety. They form part of the railing system and prevent falls by providing support and stability. In most areas, building codes require balusters or spindles to be spaced no wider than 99mm apart to meet safety standards. Check local building codes to ensure compliance for your specific project.

Staircase spindles, or balusters, should generally be spaced about 99mm apart. This distance is safe and aesthetically pleasing, ensuring balusters are close enough to prevent accidents, such as children or pets slipping through. Be sure to check local building codes, as some areas may have specific requirements for spindle spacing, especially in commercial settings.

Installing balusters is a relatively simple process with the right tools. Here’s how to do it:

1. Measure the Spacing: Measure the distance between the posts and mark where each baluster will go, ensuring the spacing is consistent (usually 99mm apart).
2. Cut the Balusters (if necessary): Trim the balusters to the right height using a saw, and ensure they fit snugly between the handrail and base rail.
3. Attach the Balusters: Apply wood glue to the bottom of each baluster, then insert them into the pre-drilled holes on the base rail. Secure the top of the baluster into the handrail using screws or nails.
4. Secure and Finish: Make sure all balusters are straight and firmly attached. You can add decorative finials or caps for a finished look.

Installing spindles is similar to installing balusters, and here’s how to do it:

1. Measure the Length: Measure the length between the top and bottom of the stairs or landing where the spindles will be placed.
2. Cut the Spindles: Use a saw to trim the spindles to the correct length if needed.
3. Attach the Spindles: Apply adhesive and then position the spindles vertically between the top handrail and bottom rail. Secure them with screws or nails, ensuring each spindle is straight and tightly fixed.
4. Finishing Touches: For a neat finish, use trim or decorative caps to cover the top of the spindles.

Replacing balusters is a simple process:

1. Remove the Old Balusters: Use a crowbar or screwdriver to gently pry out the old balusters from the top and bottom. If they’re nailed in, carefully remove the nails or screws.
2. Prepare the New Balusters: Measure and cut the new balusters to the correct height.
3. Install the New Balusters: Follow the installation steps above to attach the new balusters securely in place, ensuring the spacing and alignment are consistent.

Replacing balusters is a great way to refresh your staircase without a complete overhaul.

The terms baluster and spindle are often used interchangeably, but there’s a subtle difference:

• Balusters are the vertical supports in a railing system, typically more decorative in appearance. They are the individual posts that run between the handrail and the baserail.
• Spindles are a type of baluster but are often thinner and more closely spaced. The term "spindle" is sometimes used to describe a specific style of baluster, typically more rounded or simple in design.

In both cases, these elements serve the same purpose: providing support and safety while enhancing the staircase’s look.