How to Convert Your Attic?
Structure
The biggest consideration when planning an attic conversion is the suitability of the roof structure. Most modern houses have prefabricated roof structures whereby the rafters are supported by means of “W” format roof trusses (Imagine the middle part of the
“W” touching the inner apex of your roof with the two outer supports stretching up to either side). These trusses are held together by means of “gang-nailed” brackets at the junctions. Obviously to create maximum attic space it is necessary to remove these and provide alternative supports to the rafters. This is normally done by RSJ (Rolled Steel Joist) beams on either side of the attic spanning from one gable to the other. Vertical props are then inserted between the rafters and the new beams. These beams also carry the new floor joists for the attic, which run perpendicular to the beams. This means that they carry the weight applied on the attic floor and not the original ceiling joists, which would lead to cracks in the plasterboard ceiling in bedrooms below. Altering the existing beam structure is the most difficult part of the attic conversion. To summarise, the new beams have two main functions:
Provide support for the roof rafters in lieu of the original purlins and/or trusses. (A purlin is an original supporting beam for the rafters)
Provide support for the attic floor.
Access to the attic
There are two main options to consider:
A permanent staircase
Pull-down/Ladder type stairs (see below)
The latter option may be suitable if the attic is to be used for storage or occasional hobby use. However, where access to the attic is required on a permanent basis, i.e. for a bedroom or home office, a permanent ladder must be considered. This will require sacrificing your hot press and possibly some of the attic space to achieve a stairway with an acceptable pitch from a safety point of view. Once you have decided on the means of access the remainder of the attic conversion is relatively straightforward.
Plumbing
This is another significant stage in attic conversion. Invariably, the cold water storage tank and the central heating system feed & expansion tank need to be relocated. This is generally because most tanks are placed in the middle of or highest point of an attic taking up valuable conversion space. Also, depending on the location of the stairs, the water cylinder may need to be relocated from the hot press. If a radiator is required in the new attic, the heating system will need to be fitted with a pressure vessel. This is largely due to the fact that an attic radiator will be situated up higher than the water tank so it is necessary to regularise this.
Electrical Installation
Lighting and socket points can be fed from their respective circuits in the bedrooms below, which eliminates the nightmare of rewiring. Consideration should also be given to the installation of TV and telephone points and it is vital that a smoke detector is installed.
Walls
The walls are constructed from timber studding and are insulated with mineral wood and dry lined with plasterboard. The ceiling must also be insulated with rock wood and a suitable vapour barrier provided. The finish for the ceiling can be either plasterboard (drylining) or tongue & groove pine sheeting.
Flooring
The floor can be finished using flooring grade chipboard, conventional tongue & groove floorboards or with any pre-finished solid oak pine floors now available.
Additional Space
For a typical three-bedroom semi-detached home with a hip roof (standard roof, triangular front slope to gutter, back slope to gutter), the converted attic will give an additional floor space in the order of 8sqm. When the house has a gable wall, i.e. no hip on the roof, the available space can be as much as 15sqm. However, bear in mind that the vast majority of this space will be well below the standard 2.4m room height we are generally accustomed to. A well-fitted attic conversion can add as much as 7,000-12,000 euro on to the value of a home.
Legal Note
If you are thinking of converting your attic into a home office or additional bedroom, make sure that the alterations comply with Building Regulations, so it is wise to consult an architect in advance.