How to Manage Your Own Extension


Plan Ahead to Build the Extension of Your Dreams

Every extension is different, but the same basic project management principles apply across the board.

There are two sides to every coin, and the subdued nature of the UK housing market has meant good news for another sector. The general reluctance to move house has led to an increase in people deciding to extend their current homes instead of upsizing to a new property, and the building industry has seen significant growth over recent months.

Planning your own extension and overseeing the works might sound daunting, but with a methodical approach, it is something that anyone can do. Let’s find out how.

Before you begin

The most important part of your project is right at the beginning, and that’s in the creation of the plans and going through the approval process. Take time to sketch out your idea, and then transform it into detailed scale drawings. Include as much detail as you can, including electrical outlets, plumbing and drainage where appropriate. You don’t need any expensive software to do this either, you can draw you own extension plans using free software, and submit it to planning yourself using the Planning Portal website.

Next, you will need to get the necessary approvals. A single storey extension to the back of your property is usually considered a permitted development and will not require planning permission, but always check with your local planning office to make sure. If you live in a terraced or semi detached house, seek party wall advice to check if you need a party wall agreement.

Week by week

With the approvals in place, you are ready to begin. Sketch out a project plan, so that you know in advance who and what will be needed when. Typically, this might take the following form:

Week 1: Foundations and footings

The ground needs to be cleared and the extension marked out. Then, the builders will dig the footings and pour in concrete for the foundations. A mini digger will be needed, so check there is enough space to get it on site.

Week 2-3: Damp proof, drainage and floors

If there is plumbing in the extension, the drain run will be dug out. Next, it is a case of putting down sand, then the damp proof membrane, and finally pouring the concrete slab. Existing drains may need to be relocated and a soakaway dug.

Week 4: External walls

Usually, this involves internal blockwork and external brickwork. These need to be attached to your existing walls using wall ties. At the same time as constructing the walls, the builders should also fit the window and door frames, so have these ready.

Week 6-7: Roof, windows and doors

If you have separate contractors constructing the roof, make sure they know when they are needed, as the moment the structure is in place, you want to get it watertight. The same goes for ensuring timely delivery of the materials. If the frames were fitted when the walls went up, it will be a quick job to fit the windows and doors. For a small extension, the roof is often the only complex part for building control, so consider using roof trusses instead of having it hand cut by a carpenter if you are not getting engineering drawings done – this can save some money.

Week 8: Electrics and plumbing

Now your extension is sealed and watertight, you can get the inside done. Electricians and plumbers often need to work together, so make sure they are coordinated.

Week 9: The break through

Now to join the two parts of the house together. The breaking through is a messy, dusty business so prepare the rest of your home accordingly.

Week 10: Finishing touches

The last step is to carry out the finishing touches. That means plastering the internal walls, decorating and fitting out your new extension. Then it’s time to decorate and pick nice carpets and flooring. Everything should already be planned down to where your favourite armchair and coffee table are going. So get the furniture in and put your feet up!