How Long Does a House Extension Take in the UK? Full Timeline for 2025 (Norfolk Guide)

If you’re planning a house extension in Norfolk, one of the first questions you’ll ask is:
“How long will the whole project take?”

The truth is, extension timelines vary based on design, size, planning requirements, and contractor availability — but this guide provides a reliable breakdown of the typical extension timeline in 2025.

Whether you're considering a single-storey kitchen extension, a two-storey addition, or a full wraparound build, this blog will help you understand what to expect at each stage.

✅ Typical House Extension Timeline (Step-by-Step)

Below is an accurate average schedule based on real-world timelines across Norfolk and the wider UK.

1. Initial Consultation & Quote

📅 1–2 weeks

Your contractor meets you, reviews your ideas, and provides a detailed estimate.
This stage includes:

• Site visit

• Measurements

• Discussing layout & functionality

• Rough cost guidance

• Timeline overview

2. Architectural Drawings

📅 2–6 weeks
(Depending on design complexity and revisions)

Professional drawings are essential for planning permission, building control, and ensuring the build is structurally sound.

3. Planning Permission (If Required)

📅 8 weeks (standard)
Some extensions fall under Permitted Development, which skips this step — saving time.

If planning is needed, allow:

• 1–2 weeks for submission

• 8 weeks for official review

• Additional time for revisions (occasionally)

4. Building Regulations Approval

📅 1–2 weeks

Building control will review:

• Structural designs

• Foundations

• Insulation

• Drainage

• Fire escapes

• Energy efficiency

This can run alongside planning permission.

5. Pre-Construction Preparation

📅 1–3 weeks

Before builders start, several tasks must be confirmed:

• Structural calculations

• Material ordering

• Scheduling labour

• Confirming utility connections

• Preparing site access

🧱 CONSTRUCTION PHASE

(Actual building work)

6. Groundworks & Foundations

📅 2–4 weeks

This includes:

• Excavation

• Foundations

• Drainage / soakaways

• Concrete pouring

Ground conditions can affect this timeline significantly.

7. Building the Structure

📅 3–8 weeks

This covers:

• External walls

• Internal blockwork

• Roof structure

• Windows & doors (first fix)

Weather can affect this stage — particularly in winter months.

8. Roof Completion & Weatherproofing

📅 1–3 weeks

Once waterproof, interior work can begin.

9. First Fix Plumbing & Electrics

📅 1–2 weeks

Installation of:

• Pipes

• Wiring

• Heating

• Ventilation

10. Insulation & Plastering

📅 1–3 weeks

Once plastering is done, the extension really begins to feel like a finished room.

11. Second Fix Carpentry & Electrics

📅 1–2 weeks

This includes:

• Doors & skirting

• Sockets & switches

• Light fittings

• Radiators

• Built-in units

12. Final Interior Finishing

📅 1–3 weeks

Depending on the project:

• Painting

• Flooring

• Tiling

• Kitchen installation

• Bathroom fitting

13. Snagging & Building Control Sign-Off

📅 1–2 weeks

Before handover, your builder will check everything:

• Finish quality

• Functionality

• Safety

• Compliance

Building control will sign off the work and provide your completion certificate.

📅 Total Timeline Summary

Single-Storey Extension:

⏳ 10–16 weeks build time

• design & permissions

Two-Storey Extension:

⏳ 14–24 weeks build time

• design & permissions

Wraparound Extension:

⏳ 18–28 weeks build time

• design & permissions

Full project total:

⏳ 3–9 months overall, depending on complexity.

🔍 What Can Delay an Extension?

• Planning permission objections

• Bad weather

• Structural challenges

• Material delays

• Changes to scope mid-build

• Ground issues (roots, drainage, clay soil)

Working with an experienced Norfolk builder helps minimise delays.

🔨 Why Timeframes Matter

A well-planned timeline ensures:

• Cost control

• Efficient scheduling

• Minimal disruption

• Predictable handover date

• Higher quality results

Expert project management makes all the difference.

🏡 Why Choose Reeve & Son Construction?

We deliver:

• Reliable timelines

• Clear communication

• Highly skilled tradespeople

• Structural and building control certainty

• Full project management

• Premium finishes

• Transparent pricing

Homeowners across Norfolk trust us for extensions, renovations, conversions, and structural builds.

📞 Ready to Start Your Extension Project?

Contact Reeve & Son Construction today for a consultation and personalised timeline.