The special advantage of attic frames is that they enable the upper floor of a building to be totally contained within the roof, increasing the habitable area by 40-50% at little extra cost. Due to there being no triangulation in attic trusses the top and bottom chords are increased in size to be able to cater for the increased loads, such as office loads or a habitable room.
A.C. Roof Trusses Ltd are specialists in the design and manufacture of ‘Room in the Roof’, or Attic trusses. For larger ‘Room in the Roof’ trusses a ‘cap and base’ method of production can be used to create an even larger space without being limited by transport regulations. It is also possible for attic trusses to incorporate the Posi Joist floor system to give very large clear spans with the added benefits of open-web construction within the floor zone.
Attic Trusses can be designed to allow "clear span" supported at eaves only, however for longer spans it is recommended to incorporate the intermediate support near to mid-span. This will allow either larger internal room dimensions or reduce the number of timber sections required.
Where a more complex attic roof layout is being planned, for example where hipped ends, corner or intersection may occur, it is recommended that a truss designer is contacted to prepare a feasibility study at an early stage of the project.