“High Quality Sealing Renovation Method That Completely Removes Existing Sealant”
—Ensuring durability equal to that of the original work, passing a total of 40 kilometers of implementation—

February 14, 2013
Takenaka Corporation

Takenaka Corporation (President: Toichi Takenaka) has applied the “High Quality Sealing Renovation Method That Completely Removes Existing Sealant,” which it developed in cooperation with Sunstar Engineering Inc. and Japan Building Technology Co., Ltd., to renovation works, and has now executed the method for a total of more than 40 kilometers. In 2012, it applied this method to renovate Toyo Seikan Kaisha Ltd.’s approximately 30,000m² Saiwai Building in Tokyo, increasing the number of implementation of the method to 26 buildings.

This newly developed method permits the removal of all deteriorated sealant※1, which is difficult to do applying conventional methods, so the renovation can ensure durability equal to that of the building when it was initially constructed, reducing the life cycle cost of a building.
These achievements have been highly evaluated, earning the 2012 Super Manufacturing Component Grand Prize and Incentive Prize awarded by the Conference for the Promotion of Monodzukuri.
Takenaka plans to continue to apply it at many projects in the future.

※1 Sealant: Important material which fills connections on exterior finishing material joints to ensure the water tightness of buildings.

■ Outline of the “High Quality Sealing Renovation Method That Completely Removes Existing Sealant”

This is a method of implementing renovation use sealant by using a sealant removal agent to soften and remove the thin layer of sealant left after the old sealant has been cut out and removed with a cutter. The sealant removal agent is a material that can be used safely without worry because limonene extracted from oranges etc. is its principal constituent. It can be applied to general purpose sealants including silicon type, modified silicon type, polysulfide type, and polyurethane type.

The work procedure is: [1] removing the deteriorated existing sealant with a cutter, [2] spreading the removal agent on the remaining thin layer of sealant with a paint brush, then between 10 minutes and two hours after applying the removal agent, removing the swollen and softened thin layer with a metal brush [3] completely removing the thin layer of sealant by washing the surface it had adhered to, and [4] placing the new sealant (see photos [1] to [4]). This method and the material have been granted two patents.

[1] Removing the deteriorated existing sealant.

[2] Applying sealant removal agent and removing the remaining thin layer.

[3] Cleaning the surface it adhered to.

[4] Placing the new sealant.

■ Trial calculation of life cycle cost

The following shows a comparative sample calculation performed assuming the service lifetime of a building is 50 years and setting the cost after 10 years as 1, to obtain the total sealing renovation cost incurred during this period when the conventional work method is used and when the newly developed method is used. The conventional method is generally removing the deteriorated sealant by cutting it out with a cutter, then immediately executing renovation use sealant.

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