Civil Engineering Reference
In-Depth Information
In this construction system it may be that the ceiling joists also add strength to the
roof structure, so it is important that you follow the installation details on the ceiling
joists accurately. I shall cover this subject in more detail in the next chapter, on roof
construction.
The bottom cord of the roof truss serves as the ceiling joist
If your house has been designed to utilise roof trusses, the bottom cord of the roof truss
serves as the ceiling joist. When roof trusses are used it is normal to fit ceiling battens
below the trusses onto which the ceiling lining is fitted. It is common for the roof trusses
to be fitted at 900 mm centres or 1.2 metre centres. The maximum spacing for ceiling
supports for most ceilings is 600 mm. The installation of ceiling battens overcomes this
issue. The ceiling battens are also useful for levelling the underside of the roof trusses to
provide you with a flat, even surface for the installation of the ceiling. Roof trusses are
generally designed to transfer the entire roof and ceiling load to the outside walls of the
house. This means that the internal walls are non-structural so you should be able to
utilise lower cost non-structural timber for their construction. In order that the weight is
transferred to the outside walls, the finished height of the internal walls will be
approximately 35 mm lower than that of the external walls. The installation of ceiling
battens will take up the difference in the height of the walls for the installation of wall
and ceiling lining.
Details on the installation of the trusses will be covered in the next chapter, on roof
construction.
