Drainage
Published: October 5, 2006
While liquid sunshine and hilly terrain makes the North Shore glorious and green, it can be bad news for your home and garden. As many homeowners discovered during last winter’s relentless rainy season, non-stop downpours can lead to serious drainage problems and hefty repair bills.
Water is the biggest problem with residential buildings and too many homes have been built with poor drainage systems and water that should run off into storm sewers ends up percolating down to the concrete foundations. But it is not just poor construction that is the issue. Subsidence is common on the North Shore because people don’t take care of their drainage systems. In older houses in particular, drainage tiles where not designed to last a lifetime.
The early tell-tale signs maybe easy to ignore as they just cause a little inconvenience but turning a blind eye and crossing your fingers will only lead to an escalating set of problems and bigger bills.
With the return of wetter weather, keep an eye out for any potential drainage problems that can be fixed before it’s too late. Even after a big rainstorm, water should drain away easily. If you are left with a big puddle on your lawn that takes days to dissipate, you have a problem. Boggy areas around your property are another sign that you need to sort out the drainage tile. As well as damaging the foundations of the house, the plants in your garden will not thrive if they have soggy roots for nine months of the year.
When I visit someone’s house, drainage defects are often the first thing I spot. The driveway will be cracked and the concrete stairway has sunk and come off its footing. Both are signs that the drainage tile is out of whack.
If you have a driveway that slopes down to your garage and there is no drain to collect and channel the rainwater it will come right into your basement and eventually start crumbling the concrete.
The worse case scenario is a house that sinks because it was built on loose soil without drainage gravel. As water seeps through the ground it will take the route of least resistance. A clay or hardpan base is much less of an issue but loose soil under the foundations can get washed away. And over time, flowing water creates cavities that can destabilize a house. I have seen 10ft cavities below the footpath of a house caused by water that had nowhere to drain.
We are currently working on a property where we are re-building the foundations. The house had sunk three inches and the window frames were so warped, that every time the owners replaced the windows they buckled. The house had to be lifted and we re-poured the foundations. This is an extreme example of what can happen but unfortunately with our combination of mountains and heavy rain it is not so unusual.
Constant damp will create ugly mold patches on your walls. And if you have traditional forced air heating ducts the mold will be hard to contain as spores are sucked into the vents and circulated around the house.
All of these issues are often associated with older homes but even some new homes are built with inadequate drainage. If runoff is coming downhill directly onto your home or trickling away from your neighbour’s property, just check that it drains at least 20ft away from your property.
If you do notice these problems, don’t wait to get it sorted out. It is often surprisingly straightforward to fix and the cure is almost immediate. We’ve taken a property that’s a foot deep in bog and within a week it was as dry as a bone - all because of new drainage tiles. Compared to the cost of lifting a house, a ring of drainage tiles is the much cheaper option.