House extensions
Planning-ready, family focused
Extensions delivered with clear timelines and tidy sites.
From single-storey rear extensions to full wraparounds, we manage every stage from planning support through to the final handover.
Planning supportBuilding control readyFixed-scope quotes
Typical extension types
- Single-storey rear
- Double storey extension
- Wraparound extension
- Kitchen & family rooms
- Open-plan refurbishments
Typical timelines
- Single-storey: 10-14 weeks
- Double storey extension: 12-20 weeks
- Wraparound: 18-24 weeks
Plan with confidence.
We align approvals, budgets, and milestones upfront so your extension stays on track.
See planning support ->Planning route checked
Permitted development or full planning reviewed early.
Engineer-led structure
Openings, RSJs, foundations, and drainage planned correctly.
Family-home delivery
Site setup, access, and tidy working planned around the home.
Portal visibility
Quotes, milestones, selections, and handover records organised.
Extension expertise
Designed around how the home should feel.
We help clients create spaces that feel intentional: kitchen extensions, open-plan family rooms, additional bedrooms, utility areas, and better connections to the garden.
Kitchen & family extensions
Open-plan layouts with structural openings, roof lights, garden access, and practical family flow.
Side returns & wraparounds
Better use of underused space, especially where the home needs width, light, and a more generous ground floor.
Two-storey extensions
Additional living space downstairs with bedrooms, bathrooms, or office space above, planned around structure and services.
Our process
How we deliver extensions
We keep everything organised from the first site visit to the final sign-off, so you stay confident throughout the build.
Site visit & concept
- Measure up and confirm access.
- Discuss layouts, finishes, and budget.
- Identify planning or building control needs.
Planning & approvals
- Coordinate drawings and engineering input.
- Support planning applications where required.
- Agree specifications and schedules in writing.
Construction & delivery
- Organised site setup and safety controls.
- Weekly updates and milestone check-ins.
- Trades coordinated to keep the programme on track.
Handover & sign-off
- Final inspection and snag resolution.
- Building control documentation provided.
- Clean handover with warranty details.
Planning support
Planning & building control
We guide you through approvals, ensuring your extension meets local requirements and building regulations.
Planning permission
We advise on permitted development or full applications and help coordinate submissions where required.
Structural design
RSJ sizing, foundations, and load calculations completed by qualified professionals.
Building control
Inspections and sign-off managed throughout the build so your documentation is complete.
What sets KBL apart
More control before the first wall comes down.
Higher-end extension clients usually want confidence before committing: what is included, what needs approval, what might affect the budget, and how the home will be protected during the works.
- Scope and exclusions documented before approval
- Programme agreed around key structural stages
- Client portal used for updates and decisions
- Handover documents collected before completion
Timeline guidance
Typical extension timelines
Indicative timeframes based on standard extension scopes.
Single-storey rear
10-14 weeks from start on site.
Double storey extension
12-20 weeks including internal finishes.
Wraparound
18-24 weeks depending on complexity.
Timelines vary based on design scope, approvals, and availability.
Budget guidance
Typical extension costs
Ballpark ranges to support early planning.
Single-storey rear
£25k-£60k depending on size and finishes.
Double storey extension
£50k-£100k with open-plan reconfiguration.
Wraparound
£75k-£150k for larger family spaces.
Costs depend on structural work, access, specification, and planning requirements. We provide a detailed quote after survey.
FAQs
House extension questions answered
Quick answers to common extension queries.
Will I need planning permission?
Some extensions fall under permitted development. We review your scope and advise on the correct route.
Do you manage building control?
Yes. We coordinate inspections and make sure all sign-offs are completed before handover.
Can we live in the property?
In most cases, yes. We plan the work to minimise disruption and keep the site tidy.
How do payments work?
We agree staged payments linked to milestones so expectations and budgets stay clear.
Start with a clear plan
Bring us your drawings, ideas, or early-stage brief.
We will review the scope, explain the likely approval route, and outline the information needed for a structured extension quote.
Discuss an extensionGet in touch
Request an extension quote
Share your plans and timeline. We will confirm availability and outline the next steps.