Unlike a complex-centered large residential area redeveloped into an apartment, in some city centered residential areas in Gangnam where Seoul apartment speculations had been further heated before and after 2000 a number of housing were formed which had been reconstructed into small multi-family villas on the ground just by increasing stories only after private houses had been demolished. Thanks to rising housing prices in Gangnam the mushrooming of small villas has risen, is transformed into a revenue type multifamily housing, and sold. Here looking at the construction status of that time, there were many cases that most of the homeowners needed to invest the fund loaned as a bank collateral in new building constructions. Accordingly as they have rushed to raise ROI(return on investment) they have come to completing the building at low-budget as soon as possible rather than the space planning considering forms and designs appropriate to the ground in new building construction planning. Recently as apartment chartered prices have soared and chartered housing problems have aggravated the population is increasing that want to buy and renovate such a small villa. Changes in our housing market that are constantly fluctuating as dwelling is not a space for living, but utilized as a tool of investment techniques require reasonable flat alternatives and design enhancing at any dimension in terms of preventing increasing economic losses due to house repairing work in the future or in order to provide people to have to renovate with small capital more livable space.