In terraced and semi — detached properties loft conversions usually require the insertion of steels into shared walls or party walls and are therefore notifiable under section 2 the Party Wall etc. Act 1996.
The act allows you to raise the party wall in order to build your loft conversion but you must bear in mind your neighbour’s future use of that wall, i.e. if they wanted a loft conversion in the future they would quite rightly request that the wall be built with the ability to support a similar loft conversion. Should they do so they will be liable for a portion of the cost of building the wall to that specification. The building owner will also be liable should additional expense be created as a result of the works they have undertaken.
Chimney breasts and stacks are the most notable party wall feature of proposed loft conversions. Stacks can often be supported where chimney breasts are removed. In some properties chimney structures may be providing buttress or “core” support to the wall in question. As such, structural calculations should be scrutinised.