Mounting Stair Railings Post to Post

Lay the bottom rail down the stairs, centered between the two posts. Position the rail with the spindle holes facing up. Trace the angle of the posts onto the bottom rail's side. Place an angle finder on the bottom rail to determine the stair's slope.

Subtract 3/16 inch from the top angled line. Use a carpenter's square to draw a second line along the rail. Repeat this step for the bottom angled line. Cut the rail along the two angled lines with a circular saw.

Lay the top rail on the stairs with the spindle holes facing down. Repeat Steps 1 and 2 with the top rail.

Determine the rail's height, according to the manufacturer's directions. Place a top bracket against the first rail post in the position to hold the top rail at the appropriate height according to your municipality's codes. Trace along the top bracket's top edge.

Measure down the height of the rail from the line you traced in Step 4. Set a bracket's bottom edge at this height. Drill 1/8-inch pilot holes through the bracket's screw holes. Secure the bracket in place with 1 1/4-inch screws.

Repeat Step 4 and 5 on the second rail post. Slide a trim piece onto either end of the bottom rail. Set the bottom rail in the bottom brackets. Set an angle finder on the rail. Its angle should match the slope of the stairs from Step 1. Drive 3/4-inch screws through the brackets' side screw holes and into the bottom rail. Push the trim pieces over the brackets.

Push the railing's spindles into the bottom rail's spindle holes. Fit the top rail over the spindles, so one spindle enters into each of the top rail's spindle holes. Set the angle finder on the top rail. The angle should match the bottom rail's angle.

Slide a trim piece and bracket onto both of the top rail's ends. Center the brackets over the posts. Push the top rail aside and drill 1/8-inch pilot holes through each of the bracket's screw holes. Secure the brackets in place with 1 1/4-inch screws.

Fit the top rail back into both brackets. Drive 3/4-inch screws through the brackets' side screw holes and into the rail. Push the trim pieces over the brackets.