Abstract The load capacity of screw fixings supporting building services, such as sprinklers in Cross Laminated Timber (CLT) ceilings was tested before, during and after exposure to fire, to investigate the risk of detachment. The pull-out strength of screw fixing in ambient conditions, during and post-fire were investigated in relation to pull-out strength versus embedment depth. The relationships between pull-out strength have been reported as functions of screw fixing embedment depth, screw dimensions, and char formation. In the experimental study, samples of standard industrial CLT were tested with two distinct types of adhesives with typical construction industry screw fixings used for the suspension of Mechanical and Electrical (M and the weakening of the timber along the length of the screw thread, resulting from the higher thermal conductivity of the screw fixing. Both these effects increased as a function of the shank width of the screw. The outcome of this study is to inform guidance on the ability of screw fixings to support M&E services beneath timber ceilings in the event of fire.
Kinnersley et al. (Thu,) studied this question.