How To Extend Your Home

How To Extend Your Home

How to extend your home in 7 stages

Extending your home can be one of the most rewarding things you can do as a home owner. It can save you the stress and emotions of having to relocate, and it can provide you with the house you always dreamed of. But where do you start?

These 7 simple steps will help you understand the process and explain how to extend your own house.

Step 1 – Define your objectives

The first step is to define what it is you are trying to achieve and to be clear on the reasons why you have decided to extend your house. After all, if you don’t know what you want to achieve, it’s a sure thing your architect or builder will struggle to give you what you want.

So, define a brief. This doesn’t have to be complicated, but it has to be sufficiently detailed to outline your objectives and aims. So if you intend to build a single storey extension to the rear of your property, normally you know why and this step is easy to do. But if you’re planning something bigger, you may want to think about what your long term aims are for the property.  Is it for you to live in or for you to sell in the future?

Step 2 – Set your budget

Now that you have some idea of what you are trying to achieve you should think about how much money you have to spend on it. The reality in construction is that you may need to adjust your ambitions in order to meet your budget, and you should be prepared for this.

You will need to factor in build costs, VAT, and professional fees (including planning, buiding control, design team, structural engineer).

If you have an architect or quantity surveyor, they should be able to provide you with budget costings for your project. Which leads to our next point.

Step 3 – Appoint an architect or architectural designer

Some people think that their builder will be able to advise on the design of their property, or that you can do it yourself. And to some extent, in certain circumstances that’s true, however  architectural professionals spend their lives designing properties, they have studied best practice in property design, and they can do your house extension plans and drawings to a professional standard that your builder will be used to and that most people simply can’t do.

In addition to this, your architect will able to provide you with advice for what statutory consents you require, such as planning and building regulations, and will be able to produce the drawings and compile and manage the applications for you.

Step 4 – Planning, Building Regulations, Party Wall


Now that you have your architect and you know what you are doing, you will most likely need to submit a planning application. You should never underestimate how much of a hurdle this can be. Whilst sometimes it goes well and the planners have no issue with your project and approve it first time, other times it can go on for many months, and in the worst cases years with planning committee meetings and site visits.

Again an architectural or planning advisor will be able to recommend and advise you whether your project will be contentious to the local planning department, and complete and manage the application for you.

Planning applications are typically decided within an 8 week period following submission. However, this can be much longer if there are problems with the applications, of which there can be many.

We strongly recommend seeking professional advice whenever you submit a planning application to minimise the stress of dealing with it yourself unless you are experienced.

Building Regulations

In addition to planning, more detailed Building Regulations drawings will need to be submitted to the local authorities building control department. Again your architect of consultant should be able to produce these for you.

Party Wall Act

One final regulation to bear in mind that often creeps up is the Party Wall Act. If you plan to do work to a wall dividing your property with another, or excavate within 3 metres of another property to form new foundations, or if you plan to build on the boundary line with another property, then the Act may well apply.

If the Party Wall Act does apply, you will need to serve notice on your adjoining owner(s) informing them of your proposed works. There are statutory timeframes for these, which can be up to 2months, which state that you cannot start work until this timeframe is over. If your neighbour consents to the works you can start. However, if they do not respond or dissent to the works you and your adjoining owner will need to appoint a surveyor. This can be an additional expense of thousands of pounds, so it is worth bearing in mind, and if you are at all unsure, talk to an expert such as a party wall surveyor or building surveyor.

Step 5 – Procure a main contractor

Once you have ticked the statutory boxes and planning has been approved, you need to get a contractor appointed to build the extension.

Traditionally your architect will complete the construction drawings and write a specification of works which will then be tendered to 3-5 contractors in order to get competitive prices for the works.

If the works are simple in their nature you may be able to invite builders to visit site, discuss your proposals, and provide quotes. However this does not give you as much cost certainty as a traditionally specified and tendered project.

If you use an architect (or if you don’t), you should put a building contract in place. The most common in the UK is the JCT suite of construction contracts. The most applicable of which to a domestic extension is the JCT MW 2011. If you choose to do it yourself, you should ensure that your contractor has confirmed in writing that he will be carrying out the works under this contract, as it covers a number of events, such as changes (variations), delay, payment procedures, as well as how to resolve disputes. You can pick up copies of the JCT Minor Works Contract for around £25 from a number of sources, including the RIBA Book Shop. It is worth purchasing a copy of this and getting it signed by the contractor and yourself.

Step 6 – Managing the build

Once you have appointed  a contractor and your all set with planning and other Regulations, it’s time to start work.

Overseeing the project can be a task in itself. You can choose to manage the build yourself or appoint someone to do it for you. We recommend that for anything but the smallest projects that you appoint someone to manage the build because it can be (often is) more complicated than you think it will be. Architects, and surveyors are well practiced at managing building contracts and should be able to provide this service.

Whilst this may seem like another expense, it can save you a lot of money in the course of the project. This is often because your contractor will probably be a lot more clued up on building than you and they can (not always, there are lots of very honest contractors out there) take advantage of this fact. Any good architect or surveyor will be able to see through most attempts by the contractor to do this and will act as a middle man between you and the contractor. They will also manage payments to the contractor, and decide how much they are entitled to be paid (which is not always what they are claiming).

Step 7- Post build

After the building is complete, you can now enjoy what you have created.

If you had a building contract in place, it is typically the case that the contractor will be liable for rectifying any defects that appear within a 6 or 12 month period. The incentive for them to do this will be a retention sum that will be held back from the final payment of typically 2.5% of the contract sum. Again, you architect or surveyor will manage this whole process for you if you have one.

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