Here we provide expert advice on how to go about designing roof for your self-build, which includes advice on pitch trusses, roof types and insulation.
Pitch effect on self-build
One of the main factors when it comes to roof truss design is working out how you can make the roof space habitable, may it be for regular living space or simple for efficient storage space. This is highly dependent on the angle of your roof – many conventional house roofs have a pitch of around 35°. While this is a standard type, this is too low to make use of loft space, unless your house has incredibly wide footprints. An angle of 45° is much preferable for loft living and brings its own problems as it can make the house look top heavy and roof dominated. You must consider the balance of look and practicality to ensure you end up with a pleasing outcome.
Rafters and Purlins vs Trusses
Now it’s time to consider what the best way is to build your roof. The traditional way is to build in on site, with carpenters fixing wall plates and ridge plates and then cutting rafters to length, of which is skillful and incredibly accurate work. Extra care is to be taken to ensure that the wind doesn’t take your roof or lead to any small damages, thus meaning that there is no sagging, moving or lift off.
Pre-fabricated roof trusses have come into the main stream thanks to the ease of use, as a crane can lift and place the truss relatively quickly and easily. This standard fink roof truss is not readily adaptable for loft living, and in recent years builders have used to use bigger attic trusses that make for an open style loft.
Insulation Set Up
Requirements for more insulation have had a dramatic effect on the way in which rooms are built. If you go for leaving the loft space empty, you can simply roll out insulation above the ceiling. If you would like to use the loft as living space, you should insulate directly under the sloping roof, but there may be the problem whereby the amount of insulation is deeper than the rafters or trusses.
There are a number of ways in which we can deal with this problem, including extra installation added to the underside, but will reduce the amount of headroom you have. Alternatively, the insulation can be palced above the rafters, and another approach is to get rid of rafters and use insulated panels laid across a series of beams.
Unusual Roof Shapes
Not everyone wants to have a conventional pitched roof and as such as mean that a roof has been designed, or the owner wants to do the roof in a different way, this sometimes allows for features such as decking, garden areas. In reality these types of roofs are not completely flat, as they have a slight slop that will ensure that there is no water pooling. It is important to understand that the success is the waterproofing through development of single ply membranes. Curved rooms are sometimes constructed from specially made composite timber beams, known as glulams.
Rooms in the Roof
Having a room in the roof is often a desirable feature of owning a building. There are a number of implications that you should consider:
- Fire escape – If the roof space is going to be habitable, you need to endure that there is an easy fire exit. If the roof storey is above 4.5m – which is highly likely then you should design a route down the front door, and all doors that open onto this route. You are not able to have an open plan staircase rising out of the kitchen or living room.
- Windows – you have some options when it comes to windows in your roof room. Roof lights are simple and cheap and allow you to open the light in the room, so are usually the solution to this stumbling block.
- Future-proofing – if you do not actually need the space imminently, you can build the space and leave it unfinished, then deicide at a later date what is required from this space. You should still consider these essential features such as fire escapes and stairs when constructing the area.