A solarium structure provides a muntinless exterior appearance by eliminating the outer retaining member of the horizontal muntins. The glazing panels are supported between an inner supporting member and an outer retaining member of the mullions and by the top and leg of an inner supporting horizontal muntin. The space between the glazing panels which overlies the legs of the T's of the substantially horizontal muntins is covered by a caulking material, which is preferably a silicone material.