Although many tenement buildings still standing have had their pots removed due to the replacement of fireplaces with central heating, there are plenty more that still have these impressive stacks of pots which help to give the buildings such character. They nearly always look uneven, with replaced pots of different heights and colours, so I've hinted at this rather than produce an absolutely regular version. Unsurprisingly, it's a model that's rather high on polys - 1122 altogther - but worth it for the authentic effect. In any case, it's likely to be used with a fair few buidings, so this should lighten the load.
The chimney is pre-set at a height suitable for the four-storey units, although there's plenty of room for variation, and enough stack for use with lower adjacent buildings. If you use it with the Roof Ridge, you'll find it easier to align rows of stacks.