Inspection Techniques Flashcards
What is a moisture meter used for and how does it work?
It is used to detect damp by measuring electrical resistance.
What are some of the limitations of a damp meter?
It only measures surface moisture
It is designed for timber and may give inaccurate reading in the presence of salts or foil backed plasterboard.
it needs to be calibrated by taking a control reading prior to use on an area of suspected damp.
What is thermography and how does it work?
Infra-red thermal imaging camera used to record minute variations in the infrared radiation emitted by structures. The technique is used for locating heating loss but can also be used to detect moisture.
What are the benefits and limitation of thermography?
Benefits include:
- non destructive
- quick
Limitation
- cold surface can be caused by a number of factors so may not be conclusive and should be confirmed using damp meter
- requires specialist training to interoperate the results accurtately
- there needs to be sufficient temperature differential to operate effectively.
What is a borescope and how does it work?
Consists of a light source, small-diameter (or flexible) tube with built-in fibre optics and a screen.
It can be used to inspect cavities by inserting it into a small hole drilled externally in the mortar course, or it can be inserted into other voids.
What are the benefits and limitation of borescopes?
Benefits include
- Minimal disruption
- inexpensive
- provides photographic or video record
Limitations include:
- presence of insulation in cavities could hamper effectiveness
- images can be inconclusive
What is a borescope and how does it work?
A calcium carbide meter is a sealed vessel which is used to mix measured samples of masonry with calcium carbide. Calcium carbide will react with moisture present within the material and produce a gas. The proportion of gas released is directly proportionate to the amount of moisture present in the material therefore by measuring amount of gas we can derive the total Moisture Content (MC) of the material tested.
What are the benefits and limitation of carbide meters?
Benefits include:
- quick on site measurement
- able to determine moisture content within wall rather than simply surface moisture
Limitations
- somewhat destructive due to the need to drill sample holes.
What is gravimetric sampling and how does it work?
A wet sample is extract and dried in a controlled environment. The change in weight is used to determine the percentage of moisture present.
How would you investigate a leaking drain?
most water companies offer a free service in leak detection.
check in inspection chamber to see if blocked
CCTV drainainge survey
How would you inspect concrete?
visual: delamination, spalling, rust
hammer tapping: listen for hollowness indicating delamination
Phenaphaylene - detects alkalinity - sprayed on freshly exposed surface, turns pink if no carbonation.
