Understanding the Cost of House Extensions and Renovations

Understanding the Cost of House Extensions and Renovations

How Early Cost Advice Can Help Homeowners Avoid Surprises

Planning a house extension or renovation is an exciting step for any homeowner. Whether you are looking to create additional living space, modernise your home, or add long-term value, understanding the true cost of the project from the outset is essential.

At Michael Garnham Associates, we regularly assist homeowners in navigating the financial aspects of extensions and renovations, helping them make informed decisions and avoid unexpected costs.

Why renovation and extension costs can vary

Unlike new-build projects, extensions and refurbishments often involve working with existing buildings, which can introduce uncertainty. Factors that commonly affect cost include:

• The condition of the existing structure

• Ground conditions and foundations

• Access restrictions and working around occupied homes

• The level of finishes and specification

• Design changes during construction

Without early cost advice, these variables can quickly lead to budgets being exceeded.

Refurbishment and Alteration project in London

The importance of early cost planning

Engaging a Chartered Quantity Surveyor at an early stage allows homeowners to gain a clear and realistic understanding of likely costs before committing to a design or builder.

Early cost planning can help by:

• Establishing a realistic project budget

• Testing design proposals against affordability

• Identifying potential cost risks early

• Prioritising spending where it adds most value

This early clarity allows homeowners and architects to shape designs that align with both aspirations and budget.

Supporting homeowners through the design process

We work closely with homeowners and their architects to provide independent, clear cost advice throughout the design stages. This often includes:

• Initial budget estimates and feasibility advice

• Cost plans as designs develop

• Advice on specification choices and cost implications

• Value engineering where required, without compromising quality

Our role is to support informed decision-making and help ensure the project remains financially manageable.

Procurement and cost control

Selecting the right builder and managing costs during construction are critical to a successful project. We can assist homeowners by:

• Preparing clear cost documentation

• Reviewing builder quotations and tenders

• Advising on payment stages and valuations

• Monitoring costs to reduce the risk of overruns

This independent oversight provides reassurance and transparency throughout the build.

A bespoke and personal service

Every home and every project is different. At Michael Garnham Associates, all services are tailored to suit the specific needs of each homeowner and project. With over 35 years’ experience in the construction industry, we bring practical insight, attention to detail, and a collaborative approach to every commission.

Thinking about an extension or renovation?

If you are considering a house extension or renovation and would like clarity on costs, we would be happy to discuss your project and provide a fee quotation for professional cost advice.

Early guidance can make all the difference to a smooth, well-managed and financially controlled project.

For more information please email us at info@michaelgarnhamassociates.co.uk