In building repair and rehabilitation become necessary, as some part of building naturally tent to deteriorate and become more defective. They may also happen due to lack of maintenance. causes of construction error :

1. accuracy of drawing.
2. Number of design omission and ambiguities.
3. Inadequacy within plans and specification.
4. Quality of facility.

Type of design error :

1. Inadequate structural design
2. Poor design detail
   1. Insufficient reinforcement at opening
   2. Inadequate provision for deflection
   3. Inadequate provision for drainage.
   4. Incompatibility of material.
   5. Neglect of creep effect.
   6. Rigid joint between precast unit.
   7. Inadequate joint spacing in slab

1.Inadequate structural design

2.Poor design detail

Construction error causes

1. May occur due to failure to followed specified procedure and good practice and out right carelessness.
2. May not lead to failure or deterioration of concrete.
3. May have adverse impact on the structure with time.

Type of construction error

1. Adding water to concrete.

1. Improper alignment of form work Effect Discontinuity of the surface of the concrete This discontinuity are unsightly in all circumstance.

2. Improper consolidation or compaction of concrete Effect Improper compaction of concrete may result in a variety of defect, the common being bug hole, honeycombing and cold joint.

3. Improper curing Curing is probably the most abuse aspect of the concrete construction process. Unless concrete is given adequate time to cure at proper humidity and temperature, it will not develop the characteristic that are expected and that are necessary to proved durability

4. Improper location of reinforced steel.

5. Movement of formwork.
6. Premature removal of shores.
7. Vibration and freshly placed concrete.
8. Improper finishing of flat concrete surface.