The type of building you can build on a plot (height restrictions, size, distance to neighbors etc.) is commonly referred to as the PUP. If the work that you intend to carry out is not permitted in the PUP then you will have to engage an architect to apply to the municipality to have the PUP changed. Your immediate neighbors will have to approve or object the change.
If your property is in an area protected by the national institute for monuments of culture or the building itself is listed with the institute then special approval of your design is required before any work can proceed. If the NIMC is involved the process will be longer and more complicated.
Perhaps you have bought a plot of land without a dwelling on it or the property requires so much work as to make renovation unjustified. In this instance a new build will often be a better solution than doing up an existing building. Building from scratch will also confer the flexibility to specify exactly what you want within certain regulatory guidelines. The process of building from new may take more time and necessitate more expert input.
The initial stage of a new build is the design. The lead expert is normally the architect but architectural plans will need to be accompanied by structural engineer’s plans plus designs detailing the water , sewage, electrical, heating and ventilation systems. This team will prepare the plans in accordance to the PUP. The fees payable to the design team vary from one city to another but are calculated by sq m. In the area of Sofia it is 35-50 Leva per sq m. On completion of all elements of the design an application is submitted to the local authorities for planning permission. Approval must also be sought from the electricity and water companies. If everything is approved you will receive a Permission to Build. This document expires in 5 years time if no work has been started. The design team has to sign off the works and at the end of the project the local municipality has to sign off the building before issuing Permission for Use.
Most people build single dwelling units of perhaps 200 sq m and five meters high but some investors are building much larger structures. If the structure is over 1000 sq m or 10 meters high then you are required by law to engage the services of a licensed supervision company. Their role is to ensure that the building is being built to the required standards and their fees vary averaging around two per cent of the building cost. If you are required to use one of these firms you are advised to still employ a project management company to supervise your works because the independent supervision company does not look out for the interests of the investor but simply insures the works are legal.