An expansion joint system has a cover plate; a spline attached to the cover plate along a first edge of the spline; and two portions of open celled foam, each portion being located on an opposing face of the spline. The open celled foam has a fire-retardant material infused therein and layers of waterproof elastomer disposed thereon. The spline depends from the cover plate and is positioned in a gap between substantially coplanar substrates such that the cover plate overlies the gap. Each portion of the open celled foam is compressed between a respective face of the spline and a face of one of the coplanar substrates. An intumescent material may be incorporated into the spline.