As Londoners seek a solution to the lack of space available for expanding their homes, iceberg homes are becoming increasingly popular. Like any building work, basement conversion involves noise. However, because these jobs are done by professional building firms, they do keep to normal hours. They won’t keep you awake at night, unlike the amateur DIY enthusiast who decides to start putting up shelves at midnight.

While there may be some inconvenience for neighbours during the building job, once the work is complete, there is no impact on the neighbours’ enjoyment of their property. This is in contrast to above-ground extensions, which may cut off light to neighbouring gardens or provide intrusive windows that look over the adjoining property, compromising privacy and security.

Basements don’t cause issues when finished

There may be some disruption while the work is progressing, but there would also be disruption for any kind of extension or major building work above ground. The difference is that if the work involves the basement, there is no residual concern once it’s finished.

In London, the lack of space is a real problem. In order to expand, the city builds upwards for commercial buildings and downwards for residential buildings. Building downwards is becoming much more common among ordinary house owners. Given the higher stamp duty and transaction costs involved in moving, many families find it is more cost-effective to stay put and extend into the basement. People are now looking at basements in London as a possible solution to the chronic housing shortage and the enormous cost of property.

This is also becoming a more popular option although basements were thought of as damp and dark in the past, new building techniques and high-tech materials can be used to maximise the amount of available daylight. Glass walls and a glass roof where a side return is available allow daylight to flood into the basement.

The Guardian took a look at the whole issue and highlighted the fact that dampness in the basement is no longer a stumbling block for these kinds of conversions. (Authority URL: The old technique of “tanking” is no longer used because at the tanking ceases to work properly eventually. The current approach is to manage any dampness using a cavity membrane within the foundation, which drains into a sump and is then pumped out.

The numbers add up

The Guardian also reports an interesting set of numbers, showing that digging out basements is actually cost-effective despite the difficulties of the job. It quotes a cost per square foot of GBP 1,000 to buy a property in some areas, whereas the cost of building down into the basement is closer to GBP 500 per square foot, so it’s clearly economically viable.

This trend is no longer confined to the super rich, digging out three or four floors. The real growth in basement excavation is actually occurring in modest properties, where the conversion is only one storey down and the extra space is used for living in, not for storing expensive art collections or installing multimedia playrooms.