Aventas Therm produces rigid foam board for cavity wall insulation. California, in 1908.""In 1936 he patented his design for a cavity wall insulation product. This has led to the formation of the Cavity Wall Insulation Victims Alliance (CWIVA). The ties strengthen the cavity wall. This is often incorporated into the cavity wall insulation system. In modern cavity wall construction, cavity insulation is typically added. The walls are almost two feet thick in dimension and act as a cavity wall. Failure of ties is an increasing problem with cavity wall ties made from galvanized steel. Breathing Performance; early cavity wall buildings exchange moisture readily with the indoor and outdoor environment. The other end of the rope is extended up into the cavity wall. Cavity wall insulation installed in older buildings can create problems with moisture retention. A varnish can be applied to the cavity wall to provide a good marginal seal. Cavity wall types have an inner leaf of at least 100-125mm thick concrete. A cavity wall is a type of wall that has a hollow center. A cavity wall is composed of two masonry walls separated by an air space.