Damp specialist/tradesperson to fix damp, seal cracks

Wondering if were possible with someone with experience using permaguard or similar products, to hack old plaster and paint in my utility room as it damp with plaster/paint bubbling/pealing off due to concrete stairs above as the concrete/stone stairs are above the utility room, these stairs belong with my neighbour. is there a way that you could do something in my utility room where you could apply some damp proof membrane or apply a special product in the utility room, might also need to some repointing 100% seal cracks in my neighbour's stairs to stop any water ingress.