The present disclosure provides a method of making zeolite intergrowths. In one embodiment, the present disclosure provides a method of making an AEI-based material, including the steps of: preparing a mixture of water, an alumina source, a silica source, a CHA structure directing agent, and an AEI structure directing agent, wherein the molar ratio of the CHA structure directing agent to the AEI structure directing agent is from about 1:1 to about 1:15; heating the mixture at a temperature sufficient to promote formation of crystals; and calcining the crystals at a temperature of from about 450° C. to about 750° C. to obtain a product, wherein no halide-containing reagent is employed. The AEI-based materials of the present disclosure may find particular use in selective catalytic reduction of NOx in exhaust gas streams.