The term "attic bed" may refer to a bed that is used in an attic space, or it may refer to a loft bed. Any bed can be used in an attic space as long as it fits and allows for adequate movement around the space, thereby making the bed an attic bed. Loft beds, however, feature a special design that raises the mattress high off the ground so a desk space can be created underneath it, or a storage space in general. Loft beds are not generally used in attic spaces, since they take up a fair amount of vertical space.
Refinished attic spaces are commonly used as bedrooms, in which case an attic bed will be necessary. The size of the bed will vary according to the amount of available space in the attic, as well as the size of the doorways that grant access to the attic. Mattresses must be transported through these doorways and, in many cases, stairways, so if the bed is too big to fit in these spaces, it cannot be used as an attic bed. Otherwise, any size of mattress can generally be used as long as it will fit.
Many people who refinish an attic for a bedroom space choose to use platform beds instead of more traditional beds that feature a box spring, mattress, and frame. This is done to reduce the amount of vertical space taken up by the attic bed, since the walls of the attic space are often slanted. A platform bed does not require the use of a box spring, and the platform itself may be fairly low to the ground. Some platform beds do feature headboards, though it is wise to choose a model without a headboard or with a very low headboard, again to conserve on vertical space.
If the attic is not used exclusively as a bedroom, other options exist for an attic bed. A futon, for example, can fold up into a couch when not in use; a Murphy bed can be installed in a wall so it will fold up vertically when not in use; and a rollaway bed can be folded in on itself and stowed in a closet to conserve on space when the attic is not being used as a bedroom. The most appropriate option for an attic bed will depend on storage capabilities, the intended use of the space, and the overall size of the space.