Recently government has permitted 30% of floor area for general building’s vertical addition and announced the measure that it permitted vertical addition of 2～3 stories for apartment housing remodeling. In general buildings, cases of floor extension to an existing building and vertical addition have recently appeared. Remodeling is now getting popular in some sectors.
Recently large scale projects have been used for different purposes after finishing event or is under development. World cup stadium, olympic stadium, exposition complex are the buildings to proceed the large scale performance and they completed the function before the other using. These large scale buildings should be designed with the possibility to use for other purposes as well as their own complete function of special goal from the beginning of design process. In order to use for other purposes, from the beginning of the planning phase, the flexibility of space should be enlarged. Flexibility should be obtained only through simple modification of space without major repair or remodeling work.
There are some common problems in the process of remodeling projects. Firstly, the drawings of the building were disappeared in many cases. And though in the case of having drawings, only equipment drawings or the partial architectural drawings for management exist. In case of drawing absence, it is very important that slabs, girders and beams, columns and walls, etc. should be checked for the arrangement of structural parts, size, reinforced steel bar arrangement, concrete and design strength. Secondly, many buildings have undergone neutralization of concrete, and it causes critical cracks to structure. Large scale repair for the expected remodeling buildings will have to happen no more after completion of building construction. In the building of 20～30 years old, as the time passed, a certain amount of concrete should be in the state of neutralization. Based on experience, the depth of neutralization is 20～30 mm generally. To hinder in concrete neutralization and bar corrosion, recovery of concrete alkalinity should be made up during remodeling process. Thirdly, span of columns or walls were found with the differences horizontally or vertically from the drawings. This means the difference of sizes in the same type of house units. These differences should be considered when structural parts are putting into the remodeling units.
Durability of structural body can be also acquired by improving watertightness, which can come from the increased concrete sheath depth or the strength of concrete. In the case of the large buildings, it is recommended to increase the concrete sheath depth and concrete strength in order to cope with possible future remodeling.
If the above things could be acquired, construction works would be easily performed for remodeling or the partial improvement without any big action. And with this action, sustainable using of the buildings could be possible.