This is a question I have heard many times and was even the reason my own parents didn’t extend our three bed semi to meet to demands of our own growing family when I was young. It is worth remembering that as projects vary in size, complexity and design, different professional bodies are needed.

Here is a brief description of the key professionals for a house/extension build project


An architect is qualified to design a house and to administer the contract between the client and the builder. The architect will inevitably perform a project management function in this role. An architect will often negotiate with a builder with regard to monthly and final accounts in simple domestic projects. An architect will need the service of an engineer to sign-off on the structural elements and ground conditions beyond his own architectural design.


An engineer is also qualified to design a house but engineer designed houses tend to be more basic and simple in design than architects (who tend to have more artistic flair) but an engineer is also qualified to design and comment on structural elements.


A QS is a construction professional expert in building costing. A QS is usually used by builders to estimate the costs. He is us to draw up quotations and to monitor costs throughout the project and formulate the final account.

Most domestic projects will need a contribution from each of the above professionals but a good architect or engineer may be competent to advise on several areas.

All in all a measure of each professional service adds value to a project, depending on the size and complexity.

The above are the key professional for a project but below are some others that may or may not be required;

Interior Designer

An Interior Designer will generally design the soft furnishings and loose furniture of a building. For example when a house has been designed by an architect the interior designer will choose curtains, furniture, wallpaper, wall colour, lighting etc to further an architectural design.


A landscaper will design the gardens beyond the paving, where growth is expected to take place, for example, lawns, planters, flower beds and detailing the plants, shrubs and trees for selection.

Land Surveyor

A land surveyor will survey an existing plot of land or building and draw up a survey to allow the architect to superimpose the new building works onto the drawing for costing and building purposes.

BER Asessor

A BER is a measure of the energy rating of a building which is a function of insulation quality and air tightness amongst other elements. An A-rating being the best and an F being the lowest.

Again, the nature of the project will dictate the level of professional advice required.