If you’re running out of room and your loft isn’t suitable for conversion – or if it’s already been converted – then you may want to think about going underground instead. It’s not as simple as picking up a pick-axe, though; there’s some things you need to think about first.
Do you need planning permission?
If you’re excavating a whole new basement, then you’ll need permission, but if you’re just looking to make better use of an existing one, then you probably won’t. Your first port of call should be your local planning authority, then you should talk to your neighbours if you live in a terrace or a semi. You also need to look into your regional health and safety regulations, including adding a fire escape if your basement is to become a bedroom.
Not just yet, though… There may be barriers to your plans, such as a high water table or some mains pipes. If you have one or both of these, then you won’t be able to proceed. If you are good to go, then you need to check one final thing – that you can accommodate diggers on your street and in your garden.
Getting the time right
Your builder will advise you on the length of the works – this will vary depending on how big your basement is or will be, as well as the inevitable hitches along the way. Whatever timescale your builder gives you, add another week or two onto the end. Even though you’re digging underground, you will have some disruptions and some inconvenience, so think about how much you can put up with and for how long.
Fitting in with the rest of your house
You’ll need a staircase that connects your basement to the rest of your house, as well as a fire escape if necessary. Where will the internal staircase go and where will the fire escape lead out to? You have to conserve space upstairs and make sure the escape route doesn’t take you onto a busy road, for example.
The initial costs of a basement excavation are around £2,000 per square metre, while converting an existing space is around £1,100 per sqm. That’s just the start, though, as you also need decoration, wiring, plumbing and any other accoutrements you have planned.