I have a gap of varying degrees betwen the wall and the wooden plank that runs up the stairs alongside the wall. I think they call it the wall string . I tried filling it with decorators caulk but this too has cracked and it looks really bad ow. This is a new house that is about two years old so gaps due to settlement. Any advice on how best to repair or treat before painting much appreciated. I thought of using a decorative moulding to place on top of wall string but because of the settlement the wall string seems to be narrower in places where the gap has allowed some movement of the wall string into the wall at the bottom of the stairs. No point getting builder to come back I have a better chance of falling pregnant.