How Much Does a Home Extension Cost in Horsham? | 2026 Local Pricing Guide
With property prices continuing to rise and space at a premium, many homeowners in Horsham are choosing to extend their homes rather than move. A well-planned home extension can create valuable extra living space, improve day-to-day layout and significantly increase property value — but understanding the costs involved is essential before starting.
This guide explains how much a home extension costs in Horsham, what influences pricing, the different extension options available, and how to budget realistically in 2025.
Average Home Extension Costs in Horsham
Extension costs vary depending on size, complexity and specification. As a general guide, typical home extension costs in Horsham include:
- Single-storey extension: £1,800 – £2,500 per m²
- Double-storey extension: £2,000 – £2,800 per m²
- Rear extension: £30,000 – £60,000+
- Side extension: £35,000 – £70,000+
- Wrap-around extension: £55,000 – £100,000+
These figures are indicative. Final costs depend on design choices, structural requirements and the condition of the existing property.
What Affects the Cost of a Home Extension in Horsham?
1. Size and Layout
Larger extensions naturally cost more, but layout also plays a key role. Simple open-plan designs are usually more cost-effective than layouts with multiple rooms, bathrooms or complex structural changes.
2. Type of Extension
Different extension styles come with different cost implications:
- Single-storey extensions – Lower overall cost and shorter build time
- Double-storey extensions – Higher upfront cost but better value per square metre
- Wrap-around extensions – Maximum space and transformation, but higher complexity and cost
3. Ground Conditions and Foundations
Groundworks can significantly impact costs, particularly if:
- Deeper foundations are required
- Drainage needs relocating
- Ground conditions are poor
A professional site assessment helps identify potential issues early and avoid unexpected costs.
4. Structural Alterations
Most house extensions involve some structural work, such as:
- Removing load-bearing walls
- Installing steel beams (RSJs)
- Altering roof structures
These works add complexity but are often essential for creating modern, open-plan living spaces.
5. Specification and Finishes
Internal finishes can greatly affect the final price, including:
- Flooring and tiling
- Kitchen units and appliances
- Bathroom fittings
- Windows, doors and glazing
Many homeowners choose mid-range finishes to balance quality and budget.
Do You Need Planning Permission for an Extension in Horsham?
Many home extensions fall under Permitted Development, meaning planning permission may not be required if size and design limits are respected.
Planning permission is more likely to be required for:
- Double-storey extensions
- Extensions close to boundaries
- Side or front extensions
- Properties in conservation areas or rural locations
Regardless of planning permission, Building Regulations approval is always required.
Single-Storey vs Double-Storey Extensions: Cost Comparison
Single-Storey Extensions
- Lower overall build cost
- Quicker construction time
- Ideal for kitchens, dining areas and family rooms
Best suited to homeowners improving layout rather than adding bedrooms.
Double-Storey Extensions
- Higher initial cost
- Better value per square metre
- Adds bedrooms and bathrooms
Often the better long-term solution for growing families.
How Long Does a Home Extension Take?
Typical build times include:
- Single-storey extension: 8–12 weeks
- Double-storey extension: 12–20 weeks
Timescales depend on complexity, weather conditions and material availability.
How Much Value Can an Extension Add in Horsham?
A well-designed extension can add 15–25% to a property’s value, particularly when it:
- Improves layout and flow
- Adds bedrooms or bathrooms
- Creates open-plan living space
In Horsham’s strong family housing market, extensions are often seen as a solid long-term investment.
Budgeting Tips for Your Extension Project
To keep your project on track:
- Define your requirements clearly from the outset
- Allow a 10–15% contingency for unexpected costs
- Prioritise structure and layout over high-end finishes
- Request detailed, itemised quotes
- Work with an experienced local builder
Careful planning reduces the risk of delays and budget overruns.
Why Use a Local Horsham Builder for Your Extension?
A local builder offers:
- Knowledge of Horsham housing styles and layouts
- Familiarity with local planning expectations
- Reliable project management from start to finish
- Access to trusted local suppliers and trades
Local builder experience helps ensure your extension is delivered efficiently, safely and to a high standard.
Final Thoughts
Understanding home extension costs in Horsham is a vital first step before starting any building project. While prices vary depending on size and specification, careful planning and professional advice can help you achieve excellent results within your budget.
Whether you’re extending to gain more space, improve functionality or add long-term value, a well-planned home extension remains one of the most effective property improvements in 2025.