 Wood or "frame" buildings, as now constructed, are serviceable only for periods of from twenty to fifty years.After this comparatively short term, they become unsafe for human habitation and can be utilized only for a few years more for storage, after which, if not demolished, they decay, become dangerous, and finally fall to pieces.By frequent painting, prompt repairs, renewals of roofs, sills, etc., the period of serviceability may sometimes be extended twenty to thirty years longer , but this presumes a practical knowledge of building construction, the exercise of intelligent watchfulness and judgment, and a willingness to expend money for repairs before such repairs are actually necessary— a combination seldom found in present day owners.