Beware builders who assure you it is safe to start your basement conversion without planning permission. There have been recent cases of builders bamboozling clients by saying they are approved to BS8102, so everything is okay.
BS8102 is a code defining adequate waterproofing, and that’s all it is. By no means does it cover all the regulations you need to consider when undertaking a basement conversion.
Recent press sensationalism about basement conversions has also led to the rules being interpreted differently between one London borough and another, so the support of a specialist basement company in London developments is an enormous advantage. They have the experience to manage the entire project and are a priceless source of local information and latest advice.
British Property Law
Some property owners believe that “ownership” confers the right to do whatever they want to a property. This has never been true. In law, property conveyances only confer limited rights to use the land. This is true of all types of tenure including “freeholds”. True ownership remains with the Crown or Church, who issued the leases, and other ancient laws such as Royal Highways and rights-of-way take precedence over “property rights”.
Over the years, governments and local authorities gained the right to impose their own restrictions, and clauses were appended to property deeds by previous owners. Unapproved alterations can land you in hot water.
Planning Permission
The good news is that converting existing cellars into living space does not, in principle, require planning permission. It is your right (whether local authorities approve or not). But don’t let that lull you into complacency: many particulars of your project could still require you to gain full planning permissions.
If the basement conversion is going to be a separate full-time residence you need planning permission (and it could be refused on many grounds).
If the design requires new staircases, windows, entrances or light wells, you need planning permission.
If there is substantial new excavation, including just lowering existing floor levels, you could need planning permission.
If the new basement will have a different use from the building above, e.g. offices, a shop, workshop, bar or restaurant, then the change of building use requires planning permission (and there could be additional restrictions in the deeds).
If you live in a listed building you’ll need special consent for all alterations whether externally visible or not.
Building Regulations
Any decent basement company in London will explain to you that building regulations always apply whether you need planning permission or not. These regulations are to ensure safe and adequate ventilation, fire escape routes, ceiling heights, underpinning, wiring, damp proofing, sanitation, lighting, thermal and sound insulation, energy efficiency and non toxic materials.
Legal responsibility for complying with all laws and regulation falls on property owners. Hiring a builder to manage the project cannot change this. Unapproved methods or alterations can also invalidate both your property insurance and your builder’s liability insurance, so always hire an experienced basement company in London, not a cowboy builder brandishing a BS8102.