As the value of property in London continues to increase it isn’t surprising that home owners are looking at ways of extending their living space rather than moving into bigger properties. Basement conversions are becoming a popular option with homeowners, although there are several factors to consider before deciding on converting your cellar.
1. Basement conversions require planning applications. In 2015, 1,968 planning applications for basement conversions were submitted to UK councils with 1497 of those being in London.
2. If you decide to convert your basement you need to let your insurer know, as they may reassess their estimates based on what the converted room will be used for (e.g. is it additional bedroom space) and the effects on the structure of the property.
3. If you are converting an existing basement, is there suitable and safe access within the house and if not will you be able to create access that fits with the local building codes; some local authorities require external access to be available.
4. Depending upon the extent of work to be carried out – especially where this involves lowering existing floor levels to create additional head-room, you will probably need to employ the services of a registered Structural Engineer before any work commences.
5. London properties can be affected by the level of the ground water. Historically ground water was used within industry within London which meant that the level of the water table was lower, but since the 1980s the levels have steadily increased meaning that there has been some flooding of subsurface infrastructures.
6. London has dozens of hidden underground rivers and tributaries. Many of them were hidden during the 1800’s due to pollution by waste. Although these rivers are no longer polluted they are still running under properties in London; even the queen has a river running under Buckingham Palace! It is worth investigating whether you may be going to discover a stream when you start excavation work.
Although a high-water table or a stream ‘running through’ your basement may sound problematic there are waterproofing solutions. Sump pumps can be used to drain water down a cavity membrane and into a sump chamber where it is drains away from the property. A PCA Certified Surveyor in Structural Waterproofing (CSSW) will be able to design a solution that will mean your basement remains dry and fit for purpose. The CSSW is a specialised industry qualification which requires an understanding of waterproof systems and means that the holder has the ability to comment on them; it makes the holder a Waterproof Design Specialist, once they have met further criteria from the PCA. We are pleased to say that currently two of our Surveyors are on the PCA WDS (Waterproof Design Specialist) Register.