it needs to be heated and spread at about 350 u00b0 f to 400 u00b0 f for a satsifactory binding operation in order to prevent adhesion of the panels together when stored or piled up on account of the tacky top surface of the elastomer membrane a thin plastic film 16 covers the later the film 16 is thermofusible so as to melt when the membrane is heated by a blowtorch intended to soften the membrane 12 the permanent adherence of the membrane 12 on the fiberboard 10 is obtained by depositing a layer of the adhesive 14 on the fiberboard 10 by laying the membrane 12 over it and by letting it dry the layer of adhesive 14 must be thick enough to allow a small amount to penetrate in the fiberboard while a sufficient thickness remains on the surface to allow the adherence of the membrane 12 a method for providing the right amount of adhesive over the surface of the fiberboard consists in dispersing the adhesive in longitudinal threads 18 along the fiberboard 20 as shown in fig5 the threads 18 are formed by pumps supplying the adhesive over the fiberboard 20 while the latter moves longitudinally underneath with this arrangement it is possible to supply the desired quantity of adhesive which will adequately penetrate into and spread over the fiberboard to cover the whole surface of the latter it has been found that known industrial peristaltic pumps can provide the necessary flow control.