Abstract: The invention relates to a method for treatment of blowable thermal insulation, whereby thermal insulation, such as woodfiber wool, cellulose wool, mineral wool, glass wool and/or like is being led by means of one or several filling means (3a) to a transport space (1), such as a container or like, the internal volume of which may be changed, in order to transport thermal insulation in the transport space (1) to its destination of use and to unload same from the transport space (1) to a reception point essentially by blowing carried out by a blow arrangement. Thermal insulation is being led to a filling space (1x), that is limited from the transport space (1) by means of a filling device (3b), which filling space is being expanded along filling of same by moving the filling device (3b) in the transport space (1) in the longitudinal direction of same (s1) towards unloading end (Pp) of same. The invention relates also to an apparatus operating according to the method.