Hoffmann, Inc. commonly uses a slipform technique for the construction of cast-in-place concrete chimneys and other structures. Slipform refers to a method of constructing vertical concrete structures using a mechanical moving platform system enabling continuous placement of concrete. This technique is identified as slipforming, because the deck and wall forms “slip” as the concrete is placed in the moving form. The hydraulic jacking system operates simultaneous to provide vertical movement. Most slips average 12 inches per hour. Once the slipform process begins it continues 24 hours per day unless a controlled stop is planned.