Site clearance & substandard construction pitfalls!

The plot on which our latest modern two storey home is to be built, in Thip Thani, had an existing concrete framework which needed to be removed. The structure was basically a complete concrete column and beam framework for a 2 storey home, up to roof level. This had stood unfinished for at least 5 years. In theory, this framework could have been filled in with brick walls, a roof added and then all of the finishing work carried out to give a complete home. The problem would first have been that one would be limited on the layout of the house to that already defined by the column and beam positioned. The second more serious problem, is that the internal structure of the columns and beams is a complete un-known. What size re-bar has been used? How deep are the footings? What strength concrete mix has been used? It is for this reason, that I personally would never undertake such a project and why all of this existing structure had to be removed. In actual fact, I would say that it quickly became clear that this was the right decision. The footings were clearly too shallow and too small and the re-bar used was totally unacceptable. Re-bar is the steel that puts the 're-enforced' into 're-enforced concrete'. The steel re-bar used to make the cages that provide reinforcement to the columns and beams should look like that in the second picture below - a round steel bar with an almost screw like, or gnarled appearance. These gnarls provide grip to the steel bars within the concrete, binding the steel and concrete together firmly. The contractors we used to demolish the old structure were also extracting all of the metal re-bar from the concrete for recycling. This gave us a good opportunity to inspect the re-bar used. We found that ALL of the rebar used was not what we expected, but rather a completely smooth round section, as shown in the third photo. Using this type of steel significantly reduces the integrity of the structure and has only been used here in an attempt to cut corners and save money by the original builder. In addition to this, the diameter of the steel bar was also smaller than one would expect. With the evidence from the re-bar and footings, I would also not be surprised to find that the concrete used was also of a cheaper, lower strength.

Construction of the new home is to begin in around a months time, though a firm date has not yet been set.