A rear extension project built by Austen Dawson in Great Bedwyn. Designed by Milton Architects.
If you’re feeling squeezed for space but love your home and location, a house extension might be the perfect solution. Whether you’re dreaming of a light-filled kitchen-diner, a new home office, or an extra bedroom for a growing family, extending your property can add real comfort and value.
At Austen Dawson (Construction & Mechanical) Ltd, we specialise in helping homeowners across the Cotswolds, Oxfordshire, and Gloucestershire transform their homes with expertly planned and beautifully built extensions. Here’s what you need to know before you begin your project — and how to avoid the common pitfalls along the way.
1. Define Your Goals and Budget
Before you even start thinking about plans or builders, it’s important to clarify what you want to achieve.
Are you extending for more living space, better flow, or to increase resale value?
Is it a single-storey extension, double-storey, side-return, or a loft conversion?
Will it need to include plumbing (e.g. for a bathroom or utility room)?
Once your goals are clear, it’s time to think about budget. Be realistic — building costs in the South West can vary based on design complexity, material choices, and ground conditions.
Tip: As quantity surveyors, we can help you develop an early-stage cost estimate based on typical square metre rates and local construction costs. We always recommend including a 10–15% contingency for unexpected items.
2. Understand Planning Permission Rules
Many house extensions fall under permitted development rights, meaning they don’t require formal planning permission — but that’s not always the case.
You’ll need planning permission if:
Your extension exceeds height or size limits.
Your home is in a conservation area (common across the Cotswolds).
You’re altering the roofline significantly (e.g. for a dormer loft conversion).
Your planned materials differ greatly from the existing house.
Each local authority (like Cotswold District Council or West Oxfordshire) has its own guidance. Building Control approval is separate and always required, regardless of whether planning permission is needed.
Tip: Our team can advise you on what’s needed and even handle planning submissions on your behalf, saving you time and stress.
3. Good Design Is Worth It
A well-designed extension not only adds space but enhances how you live in your home. That’s why working with a team who understand both design and build is a huge advantage.
Some key design decisions:
How will natural light be brought in? Roof lights? Bi-folds?
How will the new space connect with the rest of the house?
What heating, insulation, and ventilation systems are suitable?
At Austen Dawson, we offer a full design & build service — meaning your project benefits from a cohesive team from initial concepts through to the final finish. This approach helps avoid disconnects between architects and builders, and keeps budgets and timelines in check.
4. Know What to Expect During the Build
Once planning and design are complete, the construction phase begins. Here’s a rough idea of what the process involves:
Site setup – fencing, skip placement, material deliveries
Groundworks – foundations, drainage, utilities
Structure – walls, floors, roof
First fix – electrics, plumbing, heating
Windows & doors – installation of openings
Second fix & finishes – plastering, tiling, flooring, decorating
Snagging & handover – final touches, client sign-off
Depending on complexity, a single-storey extension might take 10–14 weeks, while a two-storey project could take 16–20 weeks.
Tip: We provide all clients with a clear build programme and regular progress updates — so you always know what’s happening and when.
5. Prepare for Disruption
Let’s be honest: any major construction project brings a degree of mess and disruption. But good planning can help reduce the impact on your daily life.
Consider how builders will access the site (side gates? through the house?).
Think about where materials and skips will go.
Will your kitchen or bathroom be out of action temporarily?
At Austen Dawson, we pride ourselves on professional, tidy sites and proactive communication. We’ll work with you to minimise disruption and keep your home secure and clean throughout the build.
6. Avoid Common Pitfalls
We often get called in to fix issues caused by poor planning or rushed decisions. Avoid these mistakes:
Going for the cheapest quote — it usually means corners will be cut or extras will pile up later.
Skipping due diligence — always check the contractor’s credentials, reviews, and previous work.
Starting without proper plans or approvals — this can lead to costly delays or enforcement notices.
Tip: Ask for a detailed, itemised quote — not just a single lump sum. We provide fully broken-down quotes with all labour and material costs clearly explained.
7. Why Homeowners Trust Austen Dawson
As a local contractor with deep roots in the Cotswolds and surrounding counties, we bring a personal, hands-on approach to every project.
Full design, build, and mechanical expertise in-house.
Clear communication and transparent costs.
Trusted by homeowners, architects, and developers alike.
Exceptional craftsmanship and attention to detail.
Whether you’re planning a rear kitchen extension in Lechlade, a two-storey build in Cirencester, or a full house renovation in Oxfordshire, we’re here to guide you from start to finish.
8. Ready to Get Started?
If you’re thinking about extending your home, the first step is a conversation. We’ll listen to your ideas, assess your property, and offer honest, expert advice — no hard sell.
Contact us today for a free consultation and estimate.
