If you have the right type of house that has always had an existing cellar, for which there has been little use up to now, the building of a proper basement or cellar extension, is a great way of adding a lot more living space to your house. Having a basement area converted into one or more living areas needs good planning and is something that needs a qualified architect like architects London to prepare plans which can be used by the builders you eventually choose for the work.
Of all the possible house extension types, basement extensions probably provide the greatest possible amount of extra space, because the basement area that can be used is the same area as the entire ground floor of your house. This means that potentially you could have a similar number of rooms in the basement extension as you already have on the ground floor. This is a serious enlargement of your living space.
Basement extensions have various uses. They can be converted into a separate self-contained flat and let out to somebody else or used by an older relative who wants a combination of independence as well as being relatively close to family. They can also be used by growing teenagers who need a bit more extra space a bit further away from the rest of the family. Of course they don’t have to be so elaborate and can simply be a much improved cellar which can be used as extra space for an office, a play area for the kids, or storage for the household paraphernalia that is overflowing upstairs.
Older houses offer the cheapest type of homes where basement extensions can be built, because they normally have an existing cellar already. This certainly doesn’t preclude building a basement into a newer house, but it will cost a lot more as the amount of excavating that needs to be done is greater as well as the amount of disruption considerably more troublesome too. The ground floor will have to be supported from underneath while the basement is excavated. If the ground floor is of solid construction, then the temporary supports will have to be quite substantial joists. All of this amounts to considerably more expensive proposition than any house with an existing basement – the costs are at least fifty percent more.
Houses from the nineteenth century often have timber suspended ground floors. These allow entry into the basement area from the outside which makes it a lot easier for access and less intrusive for those still living in the house where all the building is going on.
The factors that are going to affect the level of difficulty of the basement extension include the total area which is required, the existing basement excavation, as already mentioned above, and things like the whereabouts of the water table and what the foundations are like and how the extension is going to affect them.
If the foundations are not deep enough, then your basement extension will need underpinning. If your house has an adjoining neighbour and you are seriously thinking of having a basement extension, then any underpinning of your house will also need to be extended.