_Double Posts or Walls._--This is accomplished when building self sustaining walls by constructing a set of columns adjacent to the walls with girders from column to column and supporting floor slabs upon the girders, not permitting either columns, girders or slab to be in contact with the exterior wall. In a skeleton construction design there are twin columns, girders and beams, the inner set carrying the floor loading and the outer the building walls, the insulation lining being unbroken between them. _Varying Temperatures._--Commercial demands require a variety of temperatures, some at zero, some at fifteen degrees and some at thirty-two or over, in the one building. The maintaining of these varying temperatures in one building requires most careful designing, since the concrete everlastingly conveys cold and attempts to cut off a floor from that above can only be done by comprehensive and extravagant insulating. There have been storage houses where with a freezer situated over or under an egg room a stove was maintained in the egg room to offset the cold temperature from above or below. A dangerous, costly expedient as well as the risk of freezing eggs. To encase and isolate a room to maintain zero to fifteen degrees in it and, say, thirty-two above, it is necessary to perform the following insulating: Line the ceiling and beams; cover the floor; cover the columns, so as to really envelop the cold. When insulation is placed on the floor, naturally the question of a wearing surface over the insulation is apparent and to maintain it fire-proof this must be cement or perhaps mastic. This causes an expenditure for wearing surface over the floor insulation, increased column quantity and strength, increased deadload of floors, insulation of floor and ceiling, of columns, and this, conservatively speaking, amounts to a total of eighty-five to ninety cents per square foot of area. This over one foot is but a small amount, but on a building one hundred feet square it becomes eighty-five hundred dollars per story. _How to Sub-divide._--To meet the variety of temperatures required, subdividing the premises into sections, but doing it vertically rather than attempt to divide it horizontally, with a portion set aside for each division of temperature. If the business is of such volume as to permit this, make no attempt to insulate one floor from that above, as there is no practical way to do it and obviate an investment in insulation from which there is no return. A thorough external wall and roof insulation is strongly recommended, and the cold radiating into a room above that may be only partially filled or empty may be considered as no great loss, provided the outer contacts are eliminated or minimized.