Water Dampness / leakage / seepage Investigation - Building
1. What are the common causes of water leakage?
- * Leakage in the drainage pipes of the upper, adjacent or your own flat.
- * Leakage in the water supply pipes of the upper, adjacent or your own flat.
- * Deteriorated waterproofing of floor slabs or bath-tub seals.
- * Seepage of waste water or rain water through roof / external wall.
- 1. Dye Tracer Test
- 2. Electrical capacitance Investigation
- 3. Electrical Resistance Investigation
- 4. Microwave Leakage Testing
- 5. Infrared Thermography Testing
- 6. Pressure Test
- 7. Humidity Sensors Test
- 8. Electrical Earth Leakage Test
- 9. Flood Testing
- 10. Water Spray Test
- 11. Acoustic Leak Testing
- 1. Two common sources of water seepage in buildings are from the external, e.g. rainfall, and from above or the alleged source sites, e.g. domestic use of water.
- 2. The former is obvious and can readily be identified with certainty. The main difficulty is to identify the source/cause of water seepage coming from above (e.g. from the bathroom immediate above an alleged water seepage site).
- 3. If the parties are cooperative, there is a good chance that the problem of water seepage can be alleviated by investigating/identifying the sources and carrying out proper repair. In majority of the cases, repeated repair will have to be carried out
- Methodology 1: The alleged source site is first subjected to dyed water to simulate the water source(s). Afterwards, measurement of moisture is carried out in the alleged water seepage site. Typical examples include flooding test, water spray test and dye test. It is generally considered as the most direct means to identify/differentiate different water source(s). However, it is not applicable in majority of the cases due to non-corporation of owners/occupiers of the alleged source site thereby disallowing any flooding test, water spray test or dye test to be carried out from the alleged water seepage site.
- Methodology 2: Without simulating the water source(s), measurement of moisture is carried out in the alleged water seepage site. Source(s) and cause(s) of water seepage are interpreted from the measurement and this requires high level of professional knowledge and expertise.
- The commonly used techniques for investigating the causes and/or sources of water seepage.
- 1. Dye test - Through thickness penetration
- 2. Protimeter measurement - Limit to surface
- 3. Infrared thermography - From surface to nominal depth
- 4. Microwave moisture meter - Up to 110 mm or more
- Dye test is the most commonly used technique, inexpensive and requiring minimal technical skills. It is used by the Joint Office as the routine method for systematic investigation and is recommended as a DIY investigation tool (FEHD and BD). Dye test is carried out by ponding the alleged source site (e.g. flooding the bathroom) with dyed water (“the ponding area”). The result is positive if dye is visible from below. Recently, fluorescent dyes are used thereby signs of water seepage are observed from below by an ultraviolet light in dark condition. Quite often dye is not detected from below in the damp area (“negative results”) even though water originates from the ponding area.
- Protimeter is a device commonly used to assess the surface moisture content of a material. Surface moisture content is measured through pushing two needles/electrodes into the material. It enables rapid assessment of surface moisture content. Due to the heterogeneous properties of concrete and unknown properties of finishes on the surface of concrete, readings obtained from a protimeter cannot be taken directly as surface moisture content, unless the readings reflect very high moisture content. As precalibration of surface moisture content of concrete is virtually not possible, readings are taken from both affected areas and non-affected areas (or control points) and the values are compared to estimate the surface moisture content of affected areas
- Infrared thermography is based on the principle that wet and dry building components have different rates of heat gain and retention. This technique is normally applied using a hand-held infrared camera with recording device . Wet zone is identified based on physical characteristics of wet material with slower heat gain and heat loss. It may be able to display water paths, hidden water pipes, etc. that are close to the surface. As temperature differential can be very small (between 0.1C to 0.5C) for identifying a wet area, an uneven surface, e.g. spalling/delamination of finishes, may distort the temperature gradient making the thermographic images unreliable. this is usually the case in an affected area
- Microwave moisture meter has gained popularity in measuring the moisture content of a material. It is based on the propagation of electromagnetic waves in the material. Moisture content is estimated from the energy loss due to absorption of water. The device includes a generator and a receiver . It has the disadvantage of requiring a good contact surface for both generator and receiver which may not be possible to achieve in majority of the cases. It is also sensitive to heterogeneous nature of concrete that may cause error in the readings obtained from the measurement. As each measurement is presented as averaged moisture up to a certain depth, accuracy is also adversely affected by the presence of cavities, pipes or reinforcement embedded inside concrete.
- Apart from dye test with the advantage of identifying water path(s) or source(s) of water seepage directly, the above are all interpretive testing methods. In some cases, microwave moisture measurement may also provide good indication of the water path(s) or source(s) of water seepage but this largely depends on the quality of the test data
- Protimeter and infrared thermography can only identify the presence of moisture near the surface. As moisture measurements are indirectly assessed via electrical resistance and heat, respectively, foreign materials inside concrete may cause similar changes on the measurement to that of water. For instance, presence of salt may affect the reading and thus the accuracy of the measurement. Therefore, the data is used to compare the moisture condition between two different areas of the same material, namely control points not affected by water seepage and the affected areas.
- Data obtained from the field works has suggested that there exists no universal method that can provide reliable results to identify the cause(s) of water seepage. Method of investigation has to be determined case by case based on the condition of concrete at the surface and in the interior
- As indicated in the above, accuracy depends on the condition of the affected areas and how the tests are performed. Correct interpretation of the test results further relies on an understanding of the underlining principle; limitations; and the pros and cons of applying different methods of investigations. We are of the view that there is in lack of an expertise or a unify approach to select the proper tests; to perform the tests and/or to interpret the results. Obviously, it is very difficult if not impossible task for the parties, who are laymen to the tests, to select the tests; to perform the tests and/or to interpret the results, save and except dye test. A performance-based approach is proposed to handle water seepage in buildings.
- Pursuant to reported cases and relevant provisions in the ordinances, the standard of investigation is to be one with high degree of certainty and the investigation so conducted is able to distinguish all possible causes of water seepage. Common difficulties in resolving water seepage disputes are due to (a) inability to identify the source(s)/cause(s) of water seepage and (b) non-corporation of owners/occupiers of premises alleged of causing water seepage. In respect of (a), it depends on the condition of the affected areas; how the tests are performed; and correct interpretation of the test results. It is necessary to improve and/or develop methods of investigating water seepage. As an alternative approach, it is suggested to identify the source(s) of water seepage from moisture readings obtained from alleged water seepage sites and vibration readings obtained from exposed waste pipes without entering the alleged source sites. Further, it is desirable to shift the method of investigation from an informative approach to a consultative approach with interaction by the party/parties. We need to dedicate tools to match the accuracy/reliability of methods of investigation with the goals of the parties and the goals of the investigation and to provide the parties with opportunities to decide how they would like to proceed. By following a performance-based approach, it is possible to reduce the overall cost and time by not carrying out unnecessary and/or unreliable tests. This may ultimately assist the public to resolve the problem of water seepage in buildings.
water seepage Testing methods
WATER LEAKAGE ACCURACY OF INVESTIGATION
WATER LEAKAGE COMMON METHODS OF INVESTIGATION
Common methods of investigating water seepage
1. Dye Test
2. Protimeter Measurement
3. Infrared thermography
4. Microwave moisture meter
Water Seepage Investigation List
civil ndt and mechanical ndt - non destructive testing in chennai list