Waterproofing in Wong Tai Sin

It depends on the method and area. Internal sealants and damp-proofing for a small area are the cheapest option; cavity-drain membranes and tanking cost more; a full basement or below-ground waterproofing system is the most expensive, running into five figures. The cause of the water dictates the right system.

Small sealant jobs on a minor damp patch are DIY-able, but below-ground waterproofing against groundwater pressure is specialist work — get it wrong and you trap water or flood the space. Full basement systems should be designed and installed by a qualified specialist.

A properly installed cavity-drain or tanking system can last decades, and quality membranes carry long guarantees. Cheap surface coatings applied over an unaddressed water problem fail fast. Longevity depends on correct diagnosis and installation far more than the product.

A common trap is a 'free survey' that always diagnoses rising damp and sells a chemical damp-proof course, when the real cause is condensation, a leaking gutter or bridged damp course. Get an independent, qualified diagnosis before paying for injected chemicals.

In Wong Tai Sin, a small damp-proofing or sealant job sits at the low end of the national range, while basement tanking and full structural waterproofing run into four or five figures depending on area and the water pressure involved.

A bathroom or small sealant job typically runs HKD 3,000-15,000, roof or membrane systems HKD 12,000-55,000, and full structural waterproofing HKD 40,000-160,000.