The extent of wear, available parts and access affect the choice. A small repair may be reasonable on an otherwise sound compatible rail. If replacement requires specialist panel handling or rebuilding the threshold, it falls beyond the ordinary task offered here.
Existing drainage features must not be obstructed by an ordinary repair. Show the complete threshold arrangement in the enquiry. Changes to a drainage or glazing system require the appropriate expertise and are not authorised simply because the damaged rail is nearby.
Some systems accept a repair insert, while others do not. The insert must suit the profile, roller contact and available clearance. An improvised cover can change the panel height or movement, so compatibility should be established before materials are purchased.
Repair an accepted accessible rail or fit a compatible running insert or replacement section without changing the building envelope. Scope limits: Accessible non-structural running rails only. No threshold waterproofing alterations, drainage-system redesign, structural changes, major glazing or powered operators.