Christopher Debieux
As a damp proofing basement conversion specialist, this is something we take into consideration during our design, water will always find the easiest route so generally using a CDM system will direct water where you wish it to go. External work is not an option sometimes and councils take exception to having their pavements ripped up. Consult with a local damp proofing/basement conversion company, preferably PCA trained or accredited and has access to CSSW trained surveyors. Safeguard Europe based in Horsham can find you a reliable contractor in your area or advise you.