PSRA Licence No: 001187 00115

How to prepare for building an Extension!

Building an extension in today’s world can be a lot more complicated than it was a few years ago. Now we have new building regulations, planning permission and new certificates that people would not have to worry about many years ago. These new additions into the construction world can leave home owners frustrated, confused and ending up spending more money than they originally wanted to. Today we are discussing how YOU can prepare for getting an extension on your home. We will advise you on how to help you keep your build stress free and cost effective.

Planning Permission:

To start off we must address whether your extension needs planning permission or not.

Extensions that don’t require planning permission:

·       If the floor area of your house is not increased by anymore than 40 square meters.

·       If the extension does not exceed the height of the house.

·       The floor area above ground level does not exceed 12sqm for terraced or semi-detached houses, and 20 sqm for detached houses.

·       The extension does not reduce the back garden to less than25 sqm.

If your extension is not in line with these specifications, then you will need to apply for planning permission. But regardless to our guidelines, it is always wise to double check if planning permission is applicable to your extension.

How long does it take to get planning permission?

It usually takes 8-10 weeks from the time you submit the application.

Certificate of Compliance:

A certificate of compliance must be obtained by the owner of the property. You will need a certificate of compliance to certify that the building complies with building regulation 2011. This can be provided by a surveyor or architect or a suitably qualified tradesman. This must be arranged before the building starts as it will involve a range of site inspections until the completion of the project.

Why is the certificate of compliance so important?

If you are planning to pay for the extension through a mortgage, you will need to arrange a certificate of compliance to get approval from the bank. If you are considering selling your home after the completion of the extension, you will need a certificate of compliance or an Opinion on Compliance. The opinion of compliance gives an opinion that the extension with built in compliance with the building regulations at the time it was built. Otherwise, you will face great difficulty selling your home.

Starting to Plan:

The first stage in preparing your house extension for build is the planning stage. This is the most important stage. Hire a well recommended good architect, you can check the website to find an architect more suited to your build. A good architect will help you visualise your extension and what the outcome will look like.

Get a surveyor. Who will survey your property and tell you where there may be drains, boundary lines or any unseen obstacles related to the build. Acknowledging these problems prior to building will make the project run more smoothly and more cost effective.

Hire good builders. Do not just go with a friend, or someone who did a good job installing a wall in your house. An extension will be a structural part of your home when complete, and will involve electrical work, carpentry, labouring, bricklaying, plastering, glazing, plumbing etc. The right builder will be able to provide the right people from each required profession and minimise obstacles that may arise during the build. Look for good recommendations and references when deciding on the builder.

DONOT rush this stage! Put time and effort into the plans. From our own experience, we know that people who rush the design stage will encounter more problems later during the build. In turn, this can end up causing much more money and delay the project.

Think about what the extension can do for your house and its value:

Many people think about getting an extra room at the back of the house. It could be to extend a kitchen, put a new bedroom in or install a sunroom or conservatory. Although these are valid reasons to get an extension, you may not take into consideration what the extension will do to the rest of the house and more importantly, its value.

Before starting to plan you should write down what is good about your house and what is bad about your house, what to improve and what not to disimprove.

As an Example:

Your kitchen is small and this could be a negative aspect so you want to extend it. But your sunroom is very bright due to the amount of natural sunlight that enters it, this is a positive aspect. When planning it is important to acknowledge that you would like to extend the kitchen but not reduce any natural light that enters the sunroom.

In some cases, we have encountered people who may add an extra bedroom at the back of the house, but the shadow drawn from this new room cuts out all the sunlight that enters the kitchen. Even though you have gained an extra bedroom, you have devalued the kitchen and reduced the size of the back garden. So even though you have made your property more valuable by adding an extra bedroom, the house has lost value due to the dark kitchen and small back garden. Overall, the house has been devalued.

“Do not negate the good things and try to improve the bad things”

This is something that your architect can help you with as they would be aware of what adds value and what takes away value. It is important that this is discussed during the planning stage.


Asking someone how much an extension will cost is effectively asking “how long is a piece of string”. There is no way of being able to look an extension plan and being able to say with absolute certainty what the cost will be. One thing you will know is how much you are willing to spend and what your budget is. There are two ways of designing; you can design to what you want in your extension, or you can design to the budget. In most cases even if you have a lot of money to spend, it is much wiser to design to a definite budget as it will reduce exceeding spending costs.

Be straight with your builder and architect; set out fees before the build starts. Set out prices of everything, from pipes to wires, toilets to radiators, bricks to wood. Set your price for everything prior to building and leave yourself some extra wiggle room in the event that you may need to spend more.

DO NOT go cheap with fundamentals! These include insulation, electrics, and plumbing. All of these add value to your house so it is wise to do a proper job. We cannot overstate enough the value of insulation in a build.

By following these steps prior to building an extension, you can find yourself saving money and having a stress-free build. There will be unforeseen obstacles that are going to arise which is common in any build, but by organizing properly prior to building, you will minimize these obstacles.

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