An architect or architectural designer for design and drawings. Usually a structural engineer for investigations, design and calculations. And, sometimes, a cost consultant for a cost estimate (they are sometimes called a “quantity surveyor”).

No. Architects have the most comprehensive capability compared to “architectural designers” and architectural technologists. Because architects train in all parts of the design and construction processes. And must constantly update this training with continuous professional development.

Most architects are preferable to architectural technologists in the initial, creative, stages of the design process. Their ability to innovate, when appropriate, can solve the hardest problems. Making sure that all creative solutions are identified and explored.

Some architectural technologists are preferable in technical design to some architects (which is why architects sometimes employ architectural technologists).

Architects, only, are listed on the official register of architects. The Architects Registration Board, ARB, administers this register. To register an architect must pass certain tests. For detail see more at the ARB website. For the highest level of accreditation an architect may also, but does not have to be, a member of the RIBA.

An architectural technologist specialises in the technical part of the design process. They are usually a member of the Chartered Institute of Architectural Technologists, CIAT. Which requires certain qualifications, standards and behaviours too. For detail see more at the CIAT website.

Read more here about the relationship between the professions of architect and architectural technologist.

An “architectural designer” may not have any professional qualifications at all. Or any registration. Some were students aiming to be architects who did not complete all the qualifications. So their strengths and weaknesses have to taken on trust.

A Principal Designer (PD) is the designer you, as the client, are lawfully obliged to appoint. The PD plans, manages, monitors and co-ordinates the separate design work and outputs of other designers. On smaller projects the PD is often also one of those designers.

Your obligation to appoint a PD applies to construction of all buildings. Including extensions to private homes and new houses. But the obligation does not apply if only one tradesperson is being employed (so its a one-off repair, for example).

Both the CDM Regulations and Building Regulations require a PD appointment. So, in practice, one person, or organisation, usually covers the requirements of both types of Regulations.

On a project to extend your home, if you do not appointment a PD, then the designer you appoint will automatically become the PD. (And the builder you employ automatically becomes the Principal Contactor). Both PD and PC have no choice but to accept their roles. And carry out their duties in them.

So you need a PD to proceed lawfully. In practice you also need a PD for the final sign-off process in connection with Building Regulations. When the building is finished, and before you occupy it, you should obtain a Completion Certificate (CC) from the building inspector. It confirms that the building is built compliant with building regulations.

Issue of the CC by the building inspector depends on two key factors. Firstly, on their satisfactory inspections at certain stages during construction. Secondly, on their receipt of a Notice of Completion (NC).

This NC is your own confirmation that the work complies with building regulations. The NC must be signed by you the client, the Principal Contractor (your builder) and the PD. Read more about all this here.

So if there’s no Principal Designer to sign the Notice of Completion you can’t get the Completion Certificate. Meaning the completion process remains undone. This is a problem if a buyer’s solicitor searches for the Completion Certificate but there isn’t one. And its existence is often a requirement of mortgage funders and insurers.

The Construction (Design and Management) Regulations 2015 are legislation about protection of health and safety in connection with the design, construction, maintenance and eventual demolition of buildings. Read more here at the HSE website.

They apply to construction of all buildings including extensions to private homes and new houses. If you are the client for construction, and it involves more than one tradesperson (so it is not a one-off repair, for example) you have certain duties. Key amongst them is a duty to appoint a Principal Designer (PD) and a Principal Contractor (PC).

On a project to extend your home, if you do not appointment a PD, then the designer you appoint will automatically become the PD. (And the builder you employ automatically becomes the Principal Contactor). Both PD and PC have no choice but to accept their roles. And carry out their duties in them.

You always need Building Regulations approval. You also need approval under Planning legislation (unless the design is within the limits of Permitted Development).

The Building Regulations are completely separate from planning legislation. So the processes for compliance are separate too.

A capable designer knows that some decisions at the design-stage for the planning application affect the building regulations approval design-stage later.

So that capable designer considers and resolves certain technical matters before the planning application. This insight and practice avoids the risk of an ineffective planning approval. (Which you might otherwise have to pay to amend, or replace, with a second application). It also avoids unexpected costs.

No. Planning approval is granted under legislation separate to that for building regulations. Broadly, Planning approval defines “what” you build. Building regulations approval defines “how”. You can’t build lawfully with just a planning approval.

So the Planning approval is about things like:- Access, appearance, landscape design, site layout, scale and massing. It may additionally be about protection of historically valuable (Listed) buildings. And about valuable and special parts of the environment. Such as Conservation Areas and Sites of Special Scientific Interest.

But building regulations is about technical things. Such as health & safety, practical amenity for users, and efficient, careful, use of resources. It is also about standards of components, materials and workmanship.

“Permitted development” legislation permits your building with no planning formalities. Or an optional simple one. It defines various limits and requirements, such as height and exterior appearance of materials. Read the legislation in detail here.

Architects interpret this legislation as far as it applies to your extension. If your design is within the limits you do not have to make an application for Planning approval. You can, but don’t have to, apply for an optional Lawful Development Certificate from the Council. That confirms your design is Permitted Development.

For a householder application 8 weeks is defined in legislation. Read more here. But this is hardly ever achieved. Allow at least 12 weeks. Many Councils take longer still. Depending on the efficiency of the officer handling your application, complexity of the development, and on overall workload of the planning office.

Applicants have an automatic right to appeal if a decision is not made within eight weeks. That’s an appeal to central government to make a decision instead. In practice if you threaten an appeal then a Council would probably refuse the application immediately. So most applicants accept the delay.

The Council’s decision notice confirming approval states that the building must be built as in the plans in the notice. If any part of what’s built varies from those plans it is unauthorised. Potentially triggering enforcement action. The Council can force such parts to be undone. In extreme, rare cases, enforcement is demolition of entire buildings.

In practice some buildings and extensions are built differently from plans approved. But enforcement does not necessarily occur. Because no-one notifies the difference to the Council (few councils have resources to monitor construction of all approvals). But enforcement is always possible. Especially if neighbours, or the public, do notify the Council. They can recognise differences because the approved drawings are in the public domain. So comparison with what’s built is easy.

Upon notification the Council considers if the variation is “material”. Meaning it could have influenced the decision if known before the decision. Or it may consider the variation “non-material”. Meaning it’s relatively inconsequential. Alternative retrospective secondary applications can then avoid enforcement. There are two types of these depending on material status.

If you want to change the design before, or during, construction submit one or other of those two secondary application types. By, firstly, advise the Council of the change. For it to consider material status. Secondly, depending on whether the change is “non-material” or “material” the Council will tell you which type of secondary application to submit.

If “non-material” the secondary application amends the approval by submission of new drawings. Which are then substituted for the original ones. At the discretion of the planning officer. This type is a Section 96A application.

If “material” the application also requires a drawings submission. But the officer then re-processes them. Including new consultations to neighbours, the public and within the Council. This is a Section 73 application. It leads to a new approval. Or a refusal. If a refusal the original approval remains in place but of course does not contain the change in design.

Ideally yes. Look for evidence of qualifications in construction or site management. For example an NVQ, City & Guilds diploma, HNC or HND.

Many local builders were originally joiners or bricklayers. Then decided to set up as general builders. So providing you with one point of contact for all the tradespersons needed. Such as electricians, heating engineers, plasterers etc. Not all local builders will have formal qualifications. But that doesn’t mean they are not good builders. If in doubt ask them to provide you with a references to satisfied customers.

Other reliable builders are members of the Chartered Institute of Building, CIOB, or members of the Federation of Master Builders, FMB. The websites of both can guide your selection.

Part of the full service of duties of an architect includes builders identification, assessment and selection.