Guest Bedroom: The average, middle-income family home does not have a guest bedroom, so it’s not surprising that this is fast becoming the most popular choices for loft conversions.A loft bedroom is ideal – it will absorb some of the heat loss from rooms lower down in the house. The size of most lofts is also in keeping with a basic guest room, and most houses will have enough space to include a small basin.With comparatively little extra cost, a walk-in shower is an ideal accompaniment to the guest bedroom.Do not forget the wardrobe! Loft roofs slope, so make sure you include space for clothes storage in the plans before you go ahead with the conversion.Shower/Bathroom: A surprising number of lofts are being turned into extra bathrooms. These can be a godsend, especially where teenagers and guests are concerned.Lofts are easily plumbed into the main system, and most lofts will have enough space for both a bath and shower. You will need to ensure that there is sufficient water pressure for the bath/shower to operate effectively. Make sure you leave enough headroom in the shower!One note of caution though – in many houses the water tank is located in the loft, and this may need moving altogether. While this will present no problem to a qualified plumber, you will want to think about this before designing the room.If you decide to go with a bathroom, the plumbing is not complex and will simply depend on the labour charges. A plumber in London will cost more than one in Cambridgeshire. This obviously affects the cost of the job. A three-piece bathroom suite will cost anything from £500 to £3,000 more than any other habitable loft conversion.Office: Hundreds of entrepreneurs have started a firm from an office in the loft, and thanks to the Internet increasing numbers of employees are opting to work from home part-time. Whether you are setting up your own business or just want a quiet area to work, the loft can be the ideal office.As most home offices are only laid out with one user in mind, this can be a very cost effective option. You will not need the whole space, so go for a part-conversion here. This saves money, and only utilises the room that you really need.Getting a phone extension to the top of the house is easily managed, and broadband and computer installation should not present a problem.