If you’re living in a 1930s semi and dreaming of more space, you’re not alone. Homeowners across London and the South East are actively exploring 1930s semi detached house extension ideas to create bright, open-plan living spaces, modern family zones, and additional bedrooms—all without compromising the home’s original character. At KT5 Construction, we specialise in transforming these period properties with seamless and stylish extensions tailored to your lifestyle and budget.

Why Extend a 1930s Semi Detached House?

These properties are loved for their solid structure, large bay windows, and characterful facades. But they were built for a different way of life. Kitchens are often tucked away, rooms are separated, and storage is minimal. That’s where smart extensions come in.

Top reasons to extend include:

• • Creating open-plan kitchen/dining spaces

  • Adding extra bedrooms or bathrooms

  • Enhancing natural light and garden connection

  • Boosting property value by up to 20%

  • Improving energy efficiency with modern materials

The flexibility of a 1930s semi means you have multiple extension options—side return, rear, wraparound, loft, or even a double-storey addition.

Popular 1930s Semi Detached House Extension Ideas

Wraparound Ground Floor Extension

A wraparound extension combines a side return and rear extension, making the most of underused space along the side of the house.

Benefits:

• • Creates a spacious open-plan kitchen/living area

  • Improves flow and visibility across the ground floor

  • Enhances natural light with roof glazing or bifold doors

  • Ideal for busy families and entertaining

Loft Conversion with Rear Dormer

Make use of unused attic space by adding a dormer conversion. This is a practical option for gaining an extra bedroom, ensuite, or even a home office.

Features:

• • Maximises floor space with vertical walls

  • Adds value without taking garden space

  • Works well with pitched 1930s roofs

  • Ideal for growing families

Our team ensures loft conversions comply with Building Regulations and match the home’s aesthetic.

Side Return Extensions

A side return can feel small but makes a big impact when combined with smart glazing and structural redesign.

Advantages:

• • Extends narrow kitchens into usable dining or family zones

  • Adds natural light through skylights or glass walls

  • Avoids major planning hurdles under Permitted Development

Tip: Combine with internal reconfiguration for a more functional layout.

Double Storey Side or Rear Extensions

If you’re planning a long-term stay, a double-storey extension is worth considering. It adds substantial square footage across two floors—great for new bedrooms, ensuites, or studies.

Planning Note: These typically require formal permission, but KT5 can manage the entire process.

Why Choose KT5 Construction?

As experienced builders, KT5 Construction specialises in period home extensions. We bring your vision to life through practical design, honest pricing, and expert delivery.

What sets us apart:

• • Free architectural or structural design if you appoint KT5

  • Transparent quotes and no hidden costs

  • Tailored designs for every family and layout

  • Coverage across Surrey and Greater London

  • Experience in wraparound, loft, and rear extensions

We’re not just builders—we’re your project partner.

Design Tips for 1930s Extensions

Maintain the Period Charm

1930s homes have distinct features—arched porches, leaded windows, red brickwork. KT5 helps you honour these while modernising internal layouts.

We match existing materials and architectural features where needed, ensuring seamless transitions between old and new.

Open Up the Layout

One of the biggest transformations comes from opening up interior walls. Our design team uses structural calculations and steel beams to:

• • Remove bottlenecks

  • Increase usable space

  • Introduce sightlines from front to back

Frequently Asked Questions

1. Do I Need Planning Permission?

Not always. Under Permitted Development Rights, many single-storey side and rear extensions are allowed. However, double-storey and wraparound projects typically require planning approval.

KT5 provides a full design and submission service, guiding you from feasibility through to approval.

2. How Long Does an Extension Take?

• Side return or rear extension: ~10–14 weeks

• Loft conversion: ~6–8 weeks

• Double storey or complex wraparound: ~16–20 weeks

We keep clients informed at every step and ensure a realistic timeline.

3. How Much Will It Cost?

Budget depends on size, finish, and complexity. As a rough guide:

• Basic rear extension: from £1,800 per m²

• Loft conversion with dormer: from £40,000+

• Full wraparound extension: £70,000–£100,000+

We offer phased construction and value engineering to stay within your budget.

Ready to Transform Your 1930s Semi?

Let’s turn your ideas into plans, and your plans into reality. Whether you want to extend up, out, or around—KT5 Construction is here to guide you every step of the way.

📞 Contact us now for a free consultation and get expert advice on how to extend your 1930s semi-detached home with confidence and style.

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