This is a question I have been asked more than once by frustrated building owners, even owners of new buildings. Poor design can certainly be a contributory factor in leaking buildings, particularly modern buildings.
“Surely modern buildings are less likely to leak than older buildings” is a not uncommon response to this answer. Logically you would think so, but unfortunately this is not necessarily the case.
Think of a traditional Melbourne weatherboard or period home, with its steeply pitched roof, eaves in proportion to the roof pitch and gutter running along the edge of the roof line. If the gutter becomes blocked, it will overflow but water will cascade onto the ground, not onto or into the building.
Now think of a modern townhouse. These are normally fitted with low angle roofs and recessed box gutters set behind parapets. If this gutter becomes blocked, the overflowing water runs down the inside of the parapet and then on top of the plaster ceiling.
So this is definitely a case of design contributing to building leaks.
Another common modern building feature, particularly with townhouses, is the inclusion of a flat balcony over a living area.
As a design feature these are certainly vulnerable to leaks. The builder is left with the problem of making this vulnerable design feature work. There are so many things to get right at the construction phase with these type of balconies, from use of good quality materials, adequate waterproofing and effective drainage so that the water will run off effectively.
So why do we end up with these problem features in so many buildings. Obviously, hidden or box gutters can increase the visual appeal of a building and including a balcony over a living area can also increase a building’s appeal, as well as its value. Designers and builders then underestimate the difficulty of keeping the building watertight. And finally deterioration over time will also lead to leaks which did not exist when the building was new.
If you are buying a home or a building, certainly look out for tell tale signs around features such as - water stains, recent repairs, water damaged timber, and internal replastering. And I would always spend the money to have a pre-purchase inspection carried out to identify existing problems, paying particular attention to gutters, drains and balconies.
So particular design features do contribute to building leaks, and it leaves the builder a limited range of options to make the building waterproof. And also a greater chance of leaks over the life of the building.
All the best, Martin