How to Build a Sturdy Banister

Hold the activation button on your stud finder. Hold the unit against the wall under your stairs. Rub the stud finder along the wall. Make a pencil mark on the wall every time the indicator light on the unit illuminates or goes out.

Cut a board to fit the height of the wall at every set of stud marks on the wall. Hold each board against the wall over its own stud. Hold your level against the side of each board to be sure it is perfectly plumb vertically. Drive a lag screw every 18 inches up each board with the hex driver bit in your drill. Countersink the head of each bolt.

Hold a post against each board mounted to the wall. Flush both sides of each post with the edges of its own board. Drive a lag bolt through the post and into the stud behind the board to secure your uprights. Do not cut any of the posts before mounting them. Remember that every post must be at least 36 inches taller than the top of the nearest stair tread.

Stretch your tape measure up the uppermost post from the top stair tread. Make a pencil mark at 36 inches. Measure and mark 36 inches up from the stair tread closest to your lowest post. Stretch the line of your chalk box between the two height marks. Pull the string and release it to leave an angled chalk line across every post. Cut along the chalk line with your reciprocating saw.

Measure from the outer edge of the bottom post to the outer edge of the top post. Add 24 inches to this measurement. Cut your handrail board (1 inch by 6 inches) to this length. Lay the handrail on top of your posts. Drive three deck screws through the handrail at each post with the Phillips bit on your drill to complete the structure of your banister.

Smooth the entire structure by rubbing the wood with medium grit sandpaper. Wipe the banister with a clean rag to remove any dust and debris. Apply three coats of latex enamel paint to the entire structure to protect the wood. Brush on each coat of paint with a natural bristle paintbrush. Let each coat dry completely before the next application.