Hidden Costs in Home Renovations: What Most Homeowners Forget to Budget For

While most homeowners allow for obvious expenses like contractor fees and materials, there are many hidden costs in home renovations that are easy to overlook. These unexpected renovation costs can add thousands to your budget if you are not prepared. Below, we cover the most common areas homeowners forget to budget for.

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Permission and Regulations

Before building work starts, you need to account for permissions, approvals and professional fees, in addition to architect/design fees. In a recent survey (2025), the typical combined cost for consultants such as party wall surveyors, planning consultants and building control was between £2,500 and £6,000 for a small house extension project.

Structural Engineer
If you are making structural changes such as removing walls or building an extension, you will need a structural engineer. Their calculations ensure the building remains safe and compliant, and adhere to building regulations. Do I need a structural engineer or an architect?

Building Regulations
Whether you use an Approved Inspector or Local Authority Building Control (LABC), approval comes with fees.
See the comparison of fees and options here.

Party Wall Surveyor
If you share walls with a neighbour, the Party Wall Act may apply. Neighbours can appoint their own surveyor, which increases your costs.
Do I need a Party Wall Surveyor?
Tip: Speak with your neighbour first to avoid disputes and additional professional costs.

Planning Permission
Some home renovation projects require planning permission. The fee is only part of the cost, as drawings and revisions add up.
How much does a planning application cost?
It may also be worth considering
planning pre-application advice to identify issues early.

Freeholder Consent
If you own a leasehold property, you may need permission from the freeholder for extensions or internal changes. This can add unexpected fees.
More detail here:
Can I build an extension without permission?

Services and Utilities

Changing the layout of your home often requires upgrades to essential services. These hidden renovation costs add up quickly:

Heating and Plumbing
Moving radiators, installing underfloor heating or upgrading old pipework can cost thousands, even on smaller projects.

Electrical Work
New sockets, rewiring and compliance with modern standards often cost more than expected. Plan furniture placement early so sockets, lighting and heating layouts can be decided in advance.

Lighting
Consider layered lighting including task, ambient and feature lighting. A well-planned scheme is more effective than relying only on ceiling spotlights and avoids retrofitting costs later.

Interior Design and Finishing Touches

Many homeowners run out of budget at this stage, yet these finishing touches make a house feel complete:

Furniture
New layouts may require new furniture, as existing pieces do not always suit the new space.

Window Dressings
Bespoke blinds and curtains are expensive but essential for privacy, insulation and aesthetics.

Artwork and Decor
Bare walls make a renovation feel unfinished. Budget for artwork, shelving and decorative elements.

Lighting Design
Statement lighting such as floor lamps, pendants and wall lights can transform a space beyond functional electrics.

Other Commonly Overlooked Home Renovation Costs

Waste Removal and Skip Hire
Construction waste often requires multiple skips, which can become expensive.

Temporary Accommodation
If your home is uninhabitable during works, hotel or rental costs can add up.

Insurance Adjustments
Standard home insurance may not cover renovation works. A specialist renovation policy is often needed.

Snagging and Maintenance
After completion, expect small fixes and adjustments in the months following.

Contingency Fund
Always set aside 10 to 20 percent of your renovation budget for unexpected issues such as drainage, outdated wiring or structural problems.

Key Takeaway

The success of a home renovation project is not just about the design and build but also the planning. Budget realistically, include hidden costs such as permissions, consultants, utilities and finishing touches, and you will avoid nasty financial surprises. By preparing for these hidden costs in home renovations, you will keep your project on track and your stress levels under control.