Planning a home renovation involves several steps, including selecting an architect and managing the construction process.

• An architect can assist in designing and outlining a significant renovation or addition, as well as supervise the construction contract.
• Consider sustainability early in the process, such as using reclaimed materials.
• Collaborate with your building contractor to identify and mitigate potential risks that could affect the cost of your construction project prior to commencing work.

Carefully planning the design and build of an extension or remodel of your kitchen and bathroom is crucial to manage the risks involved, according to specialists.

It is advisable to hire an architect for large projects, such as home extensions, as they can assist with obtaining planning permission and adhering to building regulations. Additionally, they can help you select a building contractor (referred to as a builder in the U.K.).

The RIBA spokesperson recommends considering the future use of the space when rewriting an initial brief for a project, as stated in an email to CNBC.

Before approaching architecture firms, consider your budget, advised Richard Parr, founder of design studio Richard Parr Associates.

Parr prefers to understand his clients' preferences by asking about their leisure activities and favorite vacation spots, as these can impact their design choices.

Green building

According to Ruth Lang, lead researcher in low carbon housing at the Future Observatory, a research program run by London's Design Museum, it is important to consider green credentials when focusing on any sustainability goals.

By considering how to incorporate passive heating and lighting, as well as utilizing reclaimed or natural materials, which have a lower carbon footprint, a project's conception can be significantly altered. Lang advised CNBC via email to also consult with the team on ways to minimize waste or repurpose materials.

Instead of reusing a marble kitchen countertop, you could consider using the available material for other applications, such as bathroom tiling.

Appointing an architect

The RIBA's online "Find an Architect" service requires information such as project objectives, budget, preferred design style, overall goals, and any restrictions, such as being located in a conservation area.

The BDA in Germany has approximately 5,000 members and its directory can be searched by region, while the American Institute of Architects has a searchable list of firms by state or zip code.

To determine the best architect for your project, RIBA recommends meeting with four to five firms in person to assess their portfolio, fees, construction costs, and timings. The architect will then prepare technical drawings for a builder to cost and suggest the appropriate building contract for your project.

If you don't appoint someone to oversee quality control during the build, it will be your responsibility, according to RIBA.

Budgeting

Gary Olsen, a chartered builder and director of design and build company Create, emphasized the importance of the pre-contract phase, stating that it is essential and should not be overlooked as it can prevent issues from arising later.

Olsen advised CNBC that any scope of work document should include costs that "people might not initially think of," such as parking permits and fees for dumpster or skip hire. If the builder's estimate exceeds your budget, Olsen suggested writing down your hierarchy of needs and wants and asking your contractor if they can revise it accordingly.

When meeting with potential builders, it's important to inquire if the person quoting for the work will also oversee it. If not, request a meeting with the manager who will likely be in charge of your build. As Olsen stated, "I need to be sure that I'll have a pleasant person to work with and that I'll receive payment for the work. And then, customers must determine: Can they trust this person to fulfill their promises?"

A searchable directory of building contractors by specialism and location is available through the Federation of Master Builders (FMB).

Managing risks

It is important to identify structural issues in older properties, especially in Victorian-era terraced properties with an "L"-shaped outrigger that can sink in relation to the rest of the building, said Olsen.

"A defect won't magically disappear if you hide behind a sofa looking through your fingers, hoping it won't be wrong," he said.

Before starting any work on your property, it is advisable to obtain a condition survey of your neighbor's home if you share a party wall. This survey should include photographs, descriptions, and measurements of any existing cracks or defects, according to Olsen.

Payments

If work has started, changing your mind about fixtures and fittings can be costly, Olsen pointed out.

If you choose an engineered wood floor instead of the estimated vinyl one, it may not just be the materials that cost more; the concrete base may need to be finished to a different level.

Olsen proposed establishing a WhatsApp group to discuss requested changes, confirm agreements via email, and include cost details in a spreadsheet.

The FMB's London region board president, Olsen, stated that a contractor may request approximately 5% of the build cost to secure the project, and around 20% once work commences.

Olsen advised caution against accepting large upfront payments from builders, and if a payment schedule is not provided, one should not sign the contract. After the project is finished, about 2.5% of the total cost will be retained, payable at the end of a six-month rectification period.

Renovation is not a precise science or a predictable art, so be prepared for discoveries and the unforeseen. Above all, I always tell clients to follow their gut instincts and make sure they enjoy the journey the whole way through, said Parr.