Damp Survey and Damp Proofing in Wolverton

The grid of terraced streets built by the railway company from the 1840s onwards gives Wolverton a housing stock that is unusually consistent: solid brick walls, shallow foundations, front doors opening close to pavement level, long rear yards and, originally, suspended timber floors with sub-floor airflow through airbricks front and back. Damp at low level in these houses is common, but its cause varies. Pavement and yard levels that have been built up over generations, concrete aprons laid against the wall, bridged or absent damp-proof courses and blocked airbricks all produce a similar tide mark internally. We separate them by inspecting outside as well as in, and by comparing readings at different heights and on different walls.

Terraced construction also concentrates penetrating damp problems at the party wall, the back addition and the valley or parapet gutters shared between houses. A blocked shared gutter, a failed lead flashing at a back-addition roof, or a neighbour's downpipe discharging onto a shared wall will saturate masonry that then reads wet on both sides. Where houses have been re-rendered or painted with modern impermeable coatings, trapped moisture appears as blown plaster and salt staining well away from the actual defect, which is why the pattern and timing of the dampness matters as much as the reading itself.

New Bradwell, Greenleys and Stacey Bushes bring the post-war and Milton Keynes-era housing types into the picture, including cavity masonry, timber-frame construction and some system-built and non-traditional homes. These are generally much less permeable than the Victorian terraces, so the balance of problems shifts towards condensation: cold bridges at lintels, reveals and floor-to-wall junctions, mould in unheated bedrooms and behind furniture on external walls, and extract fans that are either ineffective or discharging into the loft. Where timber frame is involved, establishing whether moisture has reached the frame itself is the priority.

Timber matters in both halves of the town. In the terraces, joist ends bearing into damp masonry, replaced solid floors that have cut off sub-floor airflow, and old beetle activity in original softwood are the usual findings, and telling historic damage from live infestation prevents unnecessary treatment. In the later housing, the concerns are roof timbers affected by long-standing leaks and any moisture reaching a structural frame. A timber inspection measures moisture content, identifies decay type where present, and states whether load-bearing members are affected.