Abstract: A water heater includes a lower skirt ring (10, 50) supporting and spacing an inner storage tank (2) above a support surface (10a), and an outer jacket (42, 54) spaced outwardly therefrom to define an annular cavity space (22) therebetween. The outer jacket is slid along the inner storage tank during assembly. A seal (46) on the inner surface of the outer jacket, preferably in the form of a rolled-in dimple, engages the inner storage tank and/or the lower skirt ring, either at a seal (44) or a flange (52), and forms a dam (48) during sliding of the outer jacket along the inner storage tank. The dam prevents leakage of liquid therepast during foaming insulation. The rolled-in dimple (56) may extend all the way through the annular space to engage the tank wall or skirt ring.