What Is the Cheapest Way to Extend a House?
Guide by BAYT

Extending your home is one of the most effective ways to add space and value without moving, but it’s no secret that costs can add up quickly.

Homeowners often ask, “What’s the cheapest way to extend?”

The truth is there’s no single answer, but there are proven strategies that help you get more value from your budget without sacrificing quality.

At BAYT, our design-and-build approach focuses on creating cost-efficient, well-planned extensions that make every euro work harder.

1. Start with Good Design, Not Guesswork

One of the biggest mistakes homeowners make when trying to save money is skipping proper design work.

Rushing straight to construction without detailed drawings often leads to costly changes later.

A well-planned design helps you:

• Maximise usable space
• Avoid expensive layout changes mid-build
• Receive accurate pricing before construction begins

At BAYT, designers and builders collaborate from day one, ensuring your plans are practical, buildable, and cost-efficient before work starts.

2. Keep the Shape Simple

Complex layouts increase costs. Every extra corner, roof junction, or bespoke feature adds labour and materials.

The most affordable extensions are typically single-storey with a simple rectangular or square footprint and a flat or lean-to roof.

Simplicity doesn’t mean boring. With thoughtful design and good finishes, even the simplest form can look modern and refined.

3. Build Out, Not Up (Sometimes)

Ground-floor extensions are often cheaper per square metre than adding a second storey, particularly where lighter foundations can be used.

However, if outdoor space is limited, building upward may still be the better solution.

At BAYT, we assess your property and advise on what’s most cost-effective for your specific site and goals, not just what appears cheapest on paper.

4. Reuse and Retain Where Possible

Reusing existing elements can lead to significant savings.

This might include:

• Retaining foundations or structural walls where feasible
• Reusing existing drainage layouts
• Integrating parts of the current heating or electrical systems

During the design phase, BAYT carefully assesses what can be retained safely while ensuring all upgrades meet modern standards.

5. Choose Cost-Effective Materials

Material choices have a major impact on the final cost.

Smart alternatives include:

• Render instead of brickwork for external walls
• Vinyl or laminate flooring instead of hardwood
• Standard aluminium or uPVC windows rather than bespoke frames

At BAYT, we help you select materials that balance appearance, durability, and cost. Small substitutions can often save thousands without affecting the overall look.

6. Avoid Last-Minute Changes

Changes made during construction almost always cost more than decisions made at the design stage.

Late changes cause delays, rework, and additional labour.

With BAYT’s design-and-build process, layouts, materials, and finishes are agreed before construction begins, keeping the project on schedule and within budget.

7. Plan for Energy Efficiency

An energy-efficient extension may cost slightly more upfront, but it saves money long-term through lower running costs and improved comfort.

Key features include:

• High-quality insulation and airtightness
• Double or triple glazed windows
• Efficient heating systems

At BAYT, energy performance is considered in every design so your extension performs well from day one.

8. Manage Everything Under One Roof

Traditional projects often involve separate architects, engineers, and builders, each with their own fees and margins.

This fragmentation can lead to miscommunication and costly errors.

BAYT’s design-and-build model offers:

• One team designing, pricing, and building your extension
• One point of contact managing all details
• One clear budget covering the full project

This efficiency reduces waste, avoids duplication, and delivers better overall value.

9. Get Permissions Early

Delays in planning permission or building control approvals can add unexpected costs.

BAYT manages all applications and ensures compliance with Irish regulations, helping avoid redesigns or hold-ups later.

10. The Smartest Way to Save

Cutting corners rarely saves money in the long run.

The most affordable way to extend your home is through careful planning, smart design, and efficient construction.

At BAYT, we help you make cost-conscious decisions without compromising on quality, comfort, or long-term value.

Ready to plan your extension?

Talk to BAYT today. Our design-and-build team will guide you from concept to completion, delivering a space that’s beautiful, efficient, and cost-effective from start to finish.