Category A works

Category a works, normally capitalised as Category A works or shortened to Cat A works, was previously most commonly associated with a category of fit-ot works, however with the introduction of the Building Safety Act and the defining of Higher-Risk Buildings (HRBs) Category A may more commonly now relate to works that are carried out to an existing HRB as defined in The Building (Higher-Risk Buildings Procedures) (England) Regulations 2023.

[edit] Category A fit-out works

Category A fit-out works are defined in the Rules of Thumb, Guidelines for building services (5th Edition) BG 9/2011, by Glenn Hawkins, published by BSRIA in 2011, as ‘Category A fit-out works extend central services out on to floor plates and provide a background for Category B works. Category A works comprise services, life safety elements and basic fittings and finishes for the operation of lettable work space. See article Category A fit-out works.

Category A works under The Building (Higher-Risk Buildings Procedures) (England) Regulations 2023 section Building control approval applications for work to existing HRB, is described in the regulation (6) as meaning work falling within any one or more of the following descriptions:

(a) work which increases or decreases the external height or width of the higher-risk building;
(b) work which changes the number of storeys the higher-risk building has (including adding or removing a mezzanine or gallery floor);
(c) work which changes the number of flats or residential rooms contained in the higher-risk building;
(d) work which changes the number of, or width of, the staircases in a higher-risk building or which changes the number of, or width of, any other escape route within the building;
(e) work to the external wall of a higher-risk building excluding work or materials of a description specified in regulation 7(3) of the 2010 Regulations;
(f) work which changes the internal layout of a higher-risk building;
(g) work which affects the passive fire safety measures in the higher-risk building;
(h) work which affects the active fire safety measures in a higher-risk building;
(i) work which affects the common parts of a higher-risk building (including the external wall) not otherwise falling within category A;

"Category A work involves significant alterations to the structure, safety, or design of a higher-risk building. This type of work generally has the potential to impact the building’s overall safety and functionality. It includes:

Structural changes: Work that increases or decreases the external height or width of the building.
Floor and layout modifications: Work that alters the number of storeys (e.g., adding or removing a mezzanine) or changes the internal layout.
Changes to living space: Work that modifies the number of flats or residential rooms within the building.
Fire safety measures: Work that impacts either passive (e.g., fire-resistant materials) or active (e.g., sprinklers or alarms) fire safety systems.
Escape routes: Work that affects the number or width of staircases or other escape routes.
Common parts and external walls: Work on the building’s common areas, including any work on the external wall that doesn’t fall under regulation 7(3) of the 2010 Regulations."

A Category B (Cat B) fit out is a type of office fit out that customizes and finishes an office space to meet a tenant's needs. It's the most common type of fit out and usually involves elements of customisation, services, installation and design. It tends to follow on from Cat A fit-out works in offices.

"Category B work is much simpler in scope. It includes all work that does not fall under Category A. In essence, if the work doesn’t significantly impact the structural, fire safety, or escape routes of the building, it is classified as Category B."