The whole story
Professor Michael Parrett
Consultant building Pathologist at UK,USA, Europe,Scandinavia, China and Hong Kong
"Achieving a professional opinion on the source of dampness means improving knowledge and understanding of building failures through the various building genres, and the techniques and equipment used as part of an overall process that is called building pathology."
Cast-iron gutters and rainwater pipes, prevalent through the Victorian and Edwardian periods, need paint protection. Unfortunately, painting schemes may miss the inside faces of these goods, which then corrode. Similar problems occur with internal cast-iron service pipes, such as soil stacks.
Connections are vulnerable where flat-roof rainwater outlets meet internal pipes, which often suffer blockages from airborne detritus. In winter, pooling water freezes and can crack the outlet.
Either problem may cause water to leak outside the drainage area down the outside of the internal pipe.
Got a question to ask?
Mike Parrett is a building pathologist, chartered building surveyor and founder of Michael Parrett Associates. He is an Eminent Fellow of RICS and the lead author on the Building Pathology Damp section of isurv.