The handrail of this deck was decaying at the mitred corners and where it butted into the posts. The end grain hadn’t been sealed with timber preservative or paint and no silicone or gap sealant was used, allowing moisture to get in.
Remove the old handrail with a pry bar and use it as a template or measure and mark out the new sections of handrail. Use a jigsaw to cut out around the posts, and a sliding compound mitresaw for the mitres.
To prevent decay, apply timber preservative or oil-based paint to the end grain. Apply construction adhesive to the top of the crossrail and exterior silicone compound along the meeting faces of timber to be butted together.
Drill pilot holes every 750mm and attach the handrail to the crossrail and posts with 65mm x 10g stainless steel square drive screws. Drive screw heads below the surface and cover them with exterior putty, then prime and paint.