Extension Beginner’s Guide
Extending is a popular way to add space without having to move. We explain everything you need to know from planning permission to costs, design work and much more
It is said that for every person who self builds there are 15 that add extensions to their homes. The reasons for all this are easy to see. It often makes more economic sense to stay put and avoids the need to find a plot. It means we can stay in the same neighbourhood if we like it and that the children can remain at the same school.
Why Should You Extend Your Home?
An overwhelming advantage of extending and not moving is the issue of stamp duty. It does not take a genius to work out that by the time you have calculated the agents fees for selling your house and the stamp duty on the one you are thinking of buying, you might well find you could build yourself quite a decent extension for the same price.
What do You Need to Consider Before Extending?
The trick is to extend and to come out well in the investment stakes, which means you have to put a lot of thought into even the smallest extension. For example, if you merely wish to extend the kitchen at the rear of your 1930s semi, should it be single storey or two? If it is the latter, what will go above it?
There are also practical issues to consider that are not directly concerned with the construction process. Access is a good example. If you add to your accommodation, will it mean more cars will need to be parked on the drive? If you have no drive then the lack of off-street parking might be a reason for the refusal of planning permission.
Similarly, if your house is in a terrace do you have rear access for the unloading of building materials or if not, will you have to bring everything from beams to blocks, and girders to guttering through the house?
Other important aspects to consider before you get to the stage of getting your plans drawn are matters like:
• soil conditions on the site;
• surrounding trees;
• any history of flooding;
• rights of way.
Another wise move is to get to know someone who has done a similar extension. They might have a builder or particular tradesman to recommend (or not recommend) but either way they will be full of useful tips on how long to allow for different tasks and many other matters.
How Much Does an Extension Cost?
There are many variables that will affect the cost of your extension such as soil type (which impacts the foundations); whether you are building a single or two storey extension; what the extension will be used for; and how much glazing you plan to specify.
Depending where you are in the UK, for a straightforward extension you should allow around £1,000–2,000/m². Remember that the standard of specification you choose will have an enormous influence on the build cost. Experienced renovator Michael Holmes, says a single storey extension will cost the following per/m².
• Basic quality £1,000 to £1,680
• Good quality £1,680 to £1,920
• Excellent quality £1,920 to £2,160
A two storey extension will not cost much more per square metre because, aside from the extra interior fixtures and finishes, you are only adding walls and floor joists — a roof and foundations are required whether your extension is single or two storey.
There are several options when it comes to borrowing money to finance your extension. However prudence is the watchword — if you borrow more than you need you might do unnecessary things in the course of the job and have difficulty paying it all back. So always be conservative.
In an ideal world, we would all finance our projects using our savings, but with recent times having offered poor interest rates, the financial landscape has been one that favours borrowers over savers. If you need to borrow the money, your best options are:
1 Credit card: If you need to borrow thousands rather than tens of thousands for your work, an interest-free credit card is a good choice. Shop around — the best deals offer up to 27 months of zero-rated spending.
2 Loan: Personal loans of up to around £25,000 are suited to smaller projects. The loan may be enough to cover the building work and if you are fitting kitchens or bathrooms in your extension you can often buy these on finance from larger stores. Just keep an eye on repayments as they can quickly add up when you borrow from several sources.
3 Remortgage or secured loan: If you are borrowing more than £25,000 you may need to remortgage your home or take our a secured loan against your home. Many building societies offer what is known as a Home Improvement Loan of up to £200,000.
Your builder will generally stage payments for each phase of the project. Try not to make any payments upfront. If it is necessary to purchase an expensive item perhaps a bathroom suite some months in advance of its installation, you should make sure it is in your name and not that of the builder, just in case they should go out of business. If necessary you should go to the place where it is stored and make sure the ownership is transferred to yourself.
Your designer will charge fees according to the work involved, so an accurate quotation of the fee would be a very useful thing to have before you give the go-ahead for plans to be prepared.
It is wise to check what any quote includes and who will pay any local authority application fees. Also, ask if any provision has been made should structural calculations be required.
If you are renovating or extending a property that you can prove has been empty for 2 years or more, it will be treated as a conversion and therefore be charged at the reduced rate of 5%. The VAT concessions are only available via a VAT registered contractor.
Will I Need Planning Permission for my Extension?
Planning consent may or may not be required for your proposed extension. Under the Permitted Development Rights system a large number of home extensions can be built without the requirement of planning permission.
• You can extend a detached dwelling by 8m to the rear if it’s single storey or 3m if it’s double.
• There are height restrictions. A single storey extension not being higher than 4m in height to the ridge and the eaves, and ridge heights of any extension not being higher than the existing property.
• Two storey extensions must not be closer than 7m to the rear boundary.
• It must be built in the same or similar material to the existing dwelling.
• Extensions must not go forward of the building line of the original dwelling.
• Side extensions must be single storey, maximum height of 4m and a width no more than half of the original building.
• In Designated Areas side extensions require planning permission and all rear extensions must be single storey.
• An extension must not result in more than half the garden being covered.
• You can only do it once and the original building is either as it was on 1st July 1948 or when it was built. In Northern Ireland it is as it was built or as it was on 1st October 1973.
You should bear in mind that if your house is in a Conservation Area or a National Park, the amount of work one can do under Permitted Development is usually reduced.
Not sure if your extension will require planning permission? Use the Real Homes planning permission tool to find out →
Your local authority has the power to remove Permitted Development Rights if it feels the character of the area wll be threatened by any new work. If in any doubt, you should check with your local authority planning department.
If you are doing an extension that will need planning permission, it is wise to pop into your local planning office to find out informally what might be permitted — especially if you are planning anything out of the ordinary. It is always wise to research the local planning policies so that you will be aware from the start that an uphill struggle awaits you if you plan anything too exotic in the area where your house is situated.
All alterations to listed buildings, including internal ones, require consent and it is a criminal offence to alter a listed building without this consent. With a listed building the planners will always regard the existing property as more important than what you are proposing to add to