Defects exist in buildings because of a number of reasons, they are generally tolerated until a point is reached where they are causing perceivable damage, or are unsightly i.e. decorative surface are peeling and discoloring.

The reasons for the damage may be difficult to determine, but generally one or more of the following is involved.

1. Poor workmanship either historic or recent.
2. Lack of regular maintenance
3. Use of inappropriate materials during repairs or renovation works.
4. Designer's lack of understanding of the effects of his proposed changes, particularly to ancient building fabric.
5. Problems created by our high expectations of building performance compared with earlier times.
6. Architects, Designers, or Tradesmen are reluctant to accept liability for their mistakes or lack of understanding of materials.

Many people proceed with major renovation projects without checking the qualifications of the people entrusted to undertake the work. It seems that price is the determining factor, only later is the error of this approach seen.