Nationwide found that on average, an extra bathroom added about 10% to a home's value. In some areas, such as London, this rose to over 15%. However, many of us don't have the space to simply build on an extra bathroom or can't afford to lose a bedroom. In this case, the best option is to steal a little space from one or two larger bedrooms to create an en-suite. With some careful planning, you can end up with a fabulous bathroom or shower room, yet not really notice the difference to your living space.

Creating an ensuite may not necessarily require architects - but you will need a good builder who knows the latest building regs like the back of his hand. See the Communities and Local Government website for more info. Bear in mind that the key to maximising the value you get from an ensuite is to make sure that the job is done well - particularly if you live in an urban area where the housing market is competitive. Any ensuite would certainly require a toilet, hand basin and shower at the very minimum, though a bath is usually preferable. This is one room, too, where you splurge a little. "For ensuites, the wow factor can make a real difference when it comes to selling, " says Hugo Headlam, associate director of London-based estate agents John D Wood.

What are the issues?
Firstly, is there enough room to add an ensuite? If you lose too much bedroom space - so a double bed no longer fits, for example - it may not be worth doing. And will you bump your head when you climb into the shower? Check the position of your existing water and waste pipes too - how easy will it be to connect these up to your new bathroom? If you are not sure, get a reliable plumber to give you some advice. And will the ensuite have a window? If not, could you have a dormer window installed to bring the light in?