Portsmouth sits on Portsea Island, surrounded by the Solent and its harbours. Its streets of Victorian terraces, many now divided into flats, face sea winds and salty air from every direction.
Wind-driven rain and salt
Strong winds push rain into defects in pointing, render and window frames. Salt in the air speeds up the decay of mortar and render, so walls that would last decades inland can deteriorate faster by the sea.
Low-lying ground
Much of the island is low-lying, so ground floors can be under moisture pressure, and older terraces with failed or bridged damp proof courses often show rising damp.
Condensation in converted flats
Southsea in particular has many large houses split into flats and student lets. Small kitchens and bathrooms, clothes drying indoors and limited ventilation make condensation and black mould common, especially in winter.
Signs to look for
- Damp patches on exposed, weather-facing walls after storms
- Tide marks and salts on ground floor walls
- Black mould around windows and in bedroom corners
- Crumbling render and eroded pointing outside
Diagnosis matters
Coastal damp is often a mix of causes. A survey will separate penetrating damp, rising damp and condensation, so each is treated properly.
Read more about damp proofing in Hampshire and condensation control in Hampshire.
