It may not always be necessary to engage an architect for your project however, there are likely to be many factors which shape and influence the building project and by having an architect beside you during the process will enable you to make informed decisions along the way. From planning legislation, Building Regulations, programming and selection of appropriate builders and obtaining building costs through to administering the building contract and helping you with the practical site stages of the works.
Equally it may not be necessary to engage an architect for the entire process. You may for instance choose only to use an architect with the initial stages of the project and then to manage subsequent stages yourself.