The existing ceiling joists are highly unlikely to have the capacity to carry the addition loads of the new domestic floor. The ceiling joists are in most cases unable to carry their own load therefore requiring suspension timbers via the purlins or rafters. The new floor must be supported at the ends on load bearing walls or beams calculated to accept the floor loads. Joists sizes are dependent on the spans involved.

The practice of laying boards on the existing ceiling joist is not recommended. Future owners may unwittingly consider the floor to be substantial. This will lead to serious damage to the ceilings or possible collapse. The lath and plaster system will not tolerate the continuous vibrations of a domestic load therefore large sections of heavy plaster eventually drop off the ceilings. A new calculated floor is independent of the existing ceilings.

The new loft floor in a three storey dwelling or over a garage will have to resist the effects of fire and smoke penetration for half an hour. This will assist you or your family to escape safely or to remain in the room until the arrival of the emergency services. Acoustic insulation blankets are installed in all cases.