Steps to Building an Extension to a House

by | Apr 1, 2024

building-an-extension-to-a -House

Building a house extension is an exciting thing to do that not only enhances your living space but also adds value to your property. In this guide, we’ll walk you through the essential steps to make your extension project a success. From understanding your rights and the necessary permits to choosing the right design and professionals, we cover it all. 

Whether you’re dreaming of a larger kitchen, an extra bedroom, or just more space to enjoy, this blog will help you navigate the journey with ease

So, get ready to transform your house into the dream home you’ve always wanted.

Assessing Your Needs and Rights       

Steps to Building an Extension to a House 4

Before diving into the world of house extensions, it’s crucial to assess your needs and understand your rights. Start by figuring out what you want from your extension. Do you need more kitchen space? A new bedroom? Or a place to relax? Knowing your goals will guide your planning.

Next, check your rights. Not all homes have the same rules when it comes to extensions. If you live in certain areas or types of houses, like flats or listed buildings, you might face restrictions. It’s important to find out if you need a full planning application or if your project falls under something called ‘permitted development rights’.So, this means you can do certain types of work without needing a full plan approved by your local council.

Also, don’t forget about building regulations. These are rules to make sure your extension is safe and meets standards for things like fire safety and insulation. You might need a package put together by an architect or engineer to show your project meets these rules.

Getting these things right at the start will save you time and trouble later on. It’s all about being prepared and knowing what’s allowed for your home’s extension.

Design and Planning

Steps to Building an Extension to a House 5

Designing your extension is a key step. Start by creating simple drawings to outline your idea. This helps you visualise the space and decide on the layout. Consider hiring an architect, as they can turn these initial sketches into detailed plans. They’ll think about how the new space will work with your current home and choose the right materials.

Your architect can also guide you through the construction plans. These are detailed instructions for the builders, showing exactly what needs to be done. Even if they’re not always required, having these plans is a good idea. They help you get accurate cost estimates and can be used as legal documents if needed.

Budgeting and Cost Considerations

Budgeting is crucial in an extension project. You need to think about how much you can spend and where that money will go. Remember, costs can go beyond just building. There might be extra expenses like architect fees or unexpected issues during construction. It’s smart to have a little extra money set aside, just in case. This is called a contingency budget. It’s usually around 15% of your total budget.

Think about what’s most important to you – cost, quality, or time. Sometimes you can’t have it all, so decide what you can compromise on. Your choices here will guide your entire project, from design to construction.

Gaining Permissions and Permits

Once your design is ready, it’s time to get the necessary permissions. This might include a building permit from your local council. A building permit is like a green light from the authorities to start your project. The process and time it takes to get this permit can vary depending on where you live and the type of work you’re doing.

In some cases, you’ll also need plans from a structural engineer, especially for larger or more complex extensions. These plans show the essential parts of your build, like foundations and load-bearing walls.

Getting these permissions is an essential step. Without them, you might have to stop your project or even undo what you’ve already built. So, make sure to have all your paperwork in order before starting any construction work.

Hiring Professionals

Choosing the right team is essential for your extension project. You’ll need different professionals like builders, plumbers, electricians, and maybe an architect. It’s important to pick experienced and trustworthy people. Look at their past work, ask for references, and check their qualifications.

When you talk to potential hires, get clear quotes from them. This means they tell you how much they think the job will cost. Also, ask about any guarantees they offer. This is a promise to fix things if something goes wrong with their work.

Remember, the cheapest option isn’t always the best. You want people who do quality work and are reliable.

Neighbour Considerations

Your extension could affect your neighbours, especially if you share walls or boundaries. It’s good to talk to them early on. Explain your plans and consider their views. If your extension is near their property, you might need something called a ‘party wall agreement’. This is a legal agreement between you and your neighbour about the work.

Also, think about issues like privacy and light. Will your extension block their sunlight or overlook their garden? It’s not just about being friendly – resolving these issues early can prevent legal problems later.

Execution and Construction Phase

Now, it’s time to start building. The construction phase has several steps:

  • Preparing the Site: This includes setting up scaffolding and arranging for tools and materials.
  • Laying Foundations: Digging and laying the groundwork for your extension.
  • Building the Structure: Erecting walls, roof, and installing doors and windows.
  • Interior Work: This covers things like insulation and reconfiguring internal spaces.
  • Internal Fit-Out: Includes plastering, flooring, plumbing, and electrics.
  • Finishing Touches: Painting, decorating, and adding final fixtures.

During this phase, keep in regular contact with your contractors. Make sure the work stays on track and matches your plans. Be prepared for some disruption to your daily life, especially if you’re living in the house during work.

Finally, once the construction is done, have a final check. This is to make sure everything is built correctly and meets safety standards. If there are any small problems (‘snags’), your contractor should fix them as part of the project.

Insurance and Safety

During construction, your regular home insurance may not cover the work being done. It’s important to check your policy and talk to your insurer. You might need extra coverage for the construction period, especially if you’re not living in the house while the work is done.

Safety is another big concern. Your extension needs to meet safety standards for things like structure, fire, and electricity. These rules are part of building regulations. Your contractor should know about these and follow them. But it’s a good idea for you to be aware of them too. This ensures your extension is not just beautiful, but also safe and legal.

Post-Construction and Final Touches

Steps to Building an Extension to a House 6

After the construction is finished, it’s time to make the space yours. This includes decorating and adding personal touches like furniture and lighting. It’s also a chance to fix any small problems or ‘snags’ you’ve noticed. This is normal and your contractor should help with these final adjustments.

Finally, arrange for a last inspection. This is usually done by local authorities or a building inspector. They check that your extension meets all the required regulations and standards. Once you get the all-clear, your new space is officially ready to enjoy.

With these steps, your extension project should go smoothly, giving you the extra space you’ve dreamed of in a safe and legal way. Remember to take your time, choose the right people, and stay informed throughout the process.

In A Nutshell

Building a house extension involves several crucial steps, from design and planning to execution and safety considerations. By understanding your needs, budgeting wisely, obtaining necessary permissions, hiring the right professionals, and considering your neighbours, you can ensure a smooth construction process. Safety and insurance are also key to protecting your investment. Once the construction is complete, adding your personal touches makes the space truly yours. 

If you’re planning an extension and looking for reliable, quality service, consider Coastal Homes for your project. They offer expert guidance and skilled craftsmanship to turn your extension dreams into reality. Contact Coastal Homes today to start your journey towards a more spacious, beautiful home.


What are the key steps in planning a home extension?

The planning process involves creating sketches and preliminary plans for layout and design, obtaining a building permit, and developing construction plans which detail the work to be done. Demolition plans may also be necessary if existing structures need to be removed​​.

Can I build an extension without planning permission?

In some cases, you can build an extension without planning permission due to “permitted development rights” for certain types of work. However, it’s crucial to check local regulations and restrictions, as these rights vary by location and the specifics of your project.

How much does it typically cost to build an extension?

The cost varies depending on factors like the specification of fixtures, site constraints, type of construction system used, and location. In Ireland, for example, extending and refurbishing a house costs between €2,900 – €3,500 per sqm, with variations based on these factors. Note that costs in Ireland may differ and should be checked locally​​.

How long does it take to start a house extension project after hiring a contractor?

Starting a house extension project typically takes about 6 ½ months, including design, permissions, and scheduling. This timeframe can be shorter for permitted development projects.

What should be considered in the design of a house extension?

When planning the design, consider the extension’s style, its impact on the rest of the house, and overall property aesthetics. Use online resources for inspiration and communicate your ideas clearly to your architect.

Is it important to discuss extension plans with neighbours?

Yes, discussing extension plans with neighbours is crucial, as the construction may affect them. Early communication can prevent future misunderstandings or disputes.

Building your dream home?

Trust Coastal Homes to make it a reality! Our experienced team of professionals is dedicated to providing top-quality construction services that meet your unique needs. Contact us today to learn more about our services.