A walled structure for an appliance comprising: (i) an inner wall portion defining a reception compartment, the reception compartment having a width; (ii) an outer wall portion facing the inner wall portion and at least partially surrounding the inner wall portion, the outer wall portion separated from the inner wall portion by a space, the outer wall portion being disposed further away from the reception compartment than the inner wall portion, the outer wall portion having a width parallel to the width of the reception compartment; (iii) an interior volume including the space between the inner wall portion and the outer wall portion; and (iv) an aperture through the outer wall portion providing access to the interior volume, the aperture having a width parallel to the widths of the reception compartment and the outer wall portion that is at least 25 percent of the width of the outer wall portion.