House extension where to start

How To Start Your House Extension
In 2023 - The Road Map

Posted by Craig | Updated May, 2024 | 10 Min Read Time

At a glance 

  • You should first find out if your property falls under permitted rights or not


In this article, you’ll find the following:

    • An explanation of building regulations for house extensions
    • Finding a trusted builder and get costs estimated

Greetings to all the homeowners and dreamers out there! It’s Craig Smith here, your trusted St Albans-based builder. Having spent over a decade perfecting the art of construction at CJ Smiths, I’m here to share with you the definitive roadmap for starting your house extension in 2023.

In the ever-changing landscape of British home design, one thing remains constant: the desire for more space. Extensions not only offer this luxury but also have the potential to significantly increase the value of your property.

Wondering where to start with a house extension? The first step is critical and sets the foundation for a successful project. With over 13 years of experience under my belt, let’s embark on this journey together.

Front house extension on Windermere avenue

You Should First Find Out If Your Property Falls Under Permitted Rights Or Not

Wondering where to start with your house extension?

Planning and Regulations - The Foundational Pillars

Before you even think about breaking ground or selecting tiles, it’s paramount to understand the planning rules and building regulations. Every house extension journey should begin with a solid foundation – in this case, thorough research.

Additionally, securing home extension insurance before commencing work is crucial to protect your project from unforeseen circumstances and ensure that your investment is safeguarded.

Permitted Development Rights

Some extensions don’t require planning permissions thanks to what’s known as “permitted development rights”. These rules vary depending on your property’s type, but in general, a rear wall of a detached home can be extended by up to 8m if it’s single-storey, and 3m for double storeys. For semi or terraced homes, it’s reduced to 6m. Always check the specifics for your area.

* **Conservation Areas & Listed Properties**: Homes in Conservation Areas or those with a Listed status have different planning rules. Always seek advice and obtain the necessary permissions.

Ground floor extension on Eagle way

Building Regulations

It’s non-negotiable; every project must comply with building regulations. Make sure your contractor understands this and can either self-certify their work or liaise with local Building Control Officers.

Financial Considerations & Insurance: Your Safety Net

Extensions can be both an investment and a cost, so a well-considered financial plan is your best ally.

Valuation & Budgeting

Start by determining whether your plans will add value to your home. Engage with local estate agents for this insight. Budgeting is then the next logical step. For reference, a 4m x 6m extension usually costs between £26,000 to £34,000.

* **Insurance**: This can’t be stressed enough. Inform your home insurance provider about your plans. Ensure your builder also has professional indemnity insurance, a must-have to cover unforeseen challenges.

Dormer loft conversion

Collaborators & Costs: Assembling Your Dream Team

To bring your vision to life, you’ll need a team of professionals who can execute your plans with precision and care.

Architects & Structural Engineers

While not always essential, for large or complex extensions, an architect can offer expertise and insights that can be invaluable. Remember, their fees typically hover around 15% of the project cost. Structural engineers, on the other hand, offer technical drawings and calculations for structural changes.

Trusted Builders

The success of your project lies in the hands of your chosen builder. Look for reliable reviews, or even better, word-of-mouth recommendations. At CJ Smiths, we pride ourselves on delivering 100% customer satisfaction. It’s this commitment to quality that has served our St Albans community so well over the years.

Costing & Quotes

We recommend reaching out to at least 5 local builders to compare pricing. Viewing previous building work is very important when it comes to making your decision with the builder you choose to build your house extension.

 Always, and I mean always, gather multiple quotes. Compare them, negotiate, and be clear about your expectations and budget.

Connecting with the Community

Last, but by no means least, remember you’re not just building for yourself but within a community. Before beginning, talk to your neighbours. Not only is it courteous, but it’s also a step that can prevent disputes later down the line. If your extension affects a party wall, ensure you understand the Party Wall Agreement. These walls, common in terraced or semi-detached houses, often require agreements between neighbours, especially for major works.


Starting a home extension in 2023 might seem daunting, but with the right roadmap, it’s a journey filled with potential and promise. If I’ve learnt anything from my time in the industry, it’s that preparation, open communication, and dedication to quality lay the foundation for success.

From the heart of St Albans, wishing you every success in your home extension venture. Here’s to creating spaces we love!

If you are still interested in finding out more about house extensions consider reading our blog on >> Why your house extension could cost you more this year


Craig Smith

The founder of CJ Smiths Construction Company for over 14+ years and a proud citizen of St Albans City.

Table of Contents

Struggling To Find A Reliable Builder For Your House Extension?

Scan the code