Buildings B

4.1 Dealing WithBuilding Defects& Nuisance1.2(d)(ii)Water Supply System (continues)Fresh water supply systemsMany old buildings still use galvanized iron (G.I. pipes for the fresh watersupply. As G.I. pipes are prone to corrosion over time, they are currentlyprohibited by the Water Authority. Maintenance works in these buildingsshould include the total replacement of the G. . pipes by suitable approvedmaterials such as copper pipes or PVC lined G.i. pipes.(iii)Seawater flushing systemsMany places in Hong Kong are supplied with sea-water for flushing purposes.Therefore, the Water Authority requires that all flushing systems should beable to withstand the attack of sea water even in areas where fresh wateris supplied for flushing. PVC pipes are commonly used for this purpose.(iv)Licenced plumberReaders are always encouraged to employ licenced plumbers in carryingout works related to the water supply system.4.1.3 Water Leakage and Drainage Nuisance(a)Roof(i)Dealing with roof leakage problemTotal replacement of agedwaterproofing construction is themost reliable method in dealingwith roof leakage problems.Partial patch repair has somelimitations, and will be discussedin detail at paragraph (vii) underthis heading.Types of waterproofing materialsThe common waterproofing materials used in Hong Kong can be classifiedbased on their application methods, namely, liquid-applied and membraneapplied.Some materials can be exposed to weather and sunlight butothers require protection such as cement sand screeding or tile finishes.Some materials are more elastic and suitable for anticipated movementsin the roof structure. Life spans of such materials range from 5 years tomore than 20 years.SELECTING THE APPROPRIATE SOLUTIONS