Basement, or underground garages are becoming more popular.
Its one way of getting a bigger house on a smaller inner suburban block.
Before you make a decision to go for this solution its worth thinking about the cost, and the risk.
They aren’t a cheap solution for a few reasons:
- There is a lot of additional excavation with all excavated soil needing to be removed. Expect to pay over$100/cubic m
- Supporting adjacent properties during excavation. You are probably going to be excavating below the foundation level of your neighbours, so its not just digging a big hole. Specialised techniques to do this safely will add to the cost
- Not only are the basement floor and walls going to be strong they are going to have to be waterproof.
- As the garage floor is probably going to be below the Storm Water Drains you will need a pumping to keep the garage dry.
The drainage company I work for has had to pump out several flooded basement garages over the past few years. The reasons for this are:
- Even in Melbourne a heavy storm can easily result in over 25mm/hour.
- For a driveway like the one in the photo above with a total area of around 100 m2 that means about 2500 litres flowing into the garage.
- With that sort of rain you might also get water coming off the street, or the garden.
- If the pump blocks, or there is a power cut the water can quickly build up.
Have you ever had problems with an underground garage?