Diagnosing damp: Accurate diagnosis, using a speedy calcium carbide meter, to undertake an in-depth damp test to determine rising dampness & moisture content in walls.
DampAid specialist damp surveyors have an array of diagnosing damp testing & home inspection equipment at their disposal to identify dampness in properties. Such as a Speedy Carbide Test. In this article we look at how surveyors test for dampness in walls using a Speedy Calcium Carbide Test method and how it helps damp testing companies in the identification and diagnosis when diagnosing damp in homes and other buildings.
A speedy calcium carbide damp test is a method used by damp specialists to determine the moisture content within damp walls in houses. This damp test procedure aids our surveyors when investigating a property for damp and helps to determine an accurate diagnosis of the dampness within a property. A speedy carbide test has a greater degree of accuracy when compared to a Protimeter that also determines the moisture levels within a damp wall. Unlike the Protimeter moisture meter the speedy carbide test is a destructive method used to test walls and requires a sample of masonry from the wall or floor. As a result a Speedy Carbide Test tends to be only carried out if it is specifically requested by the owner of the property requiring an in-depth moisture analysis of masonry & plaster. This is normally following a flood / leaking appliances. It is particularly useful when some unscrupulous insurance companies insist that the problem has been caused by rising damp (for which your insurance policy does not cover) and are refusing to pay out a claim for water damage to your property, unless you can prove otherwise. This is when the speedy moisture test apparatus comes in….the point at when we need to use the calcium carbide method to accurately determine moisture content & provide you with an impartial independent damp report and recommendations for any repairs to your house.
Speedy carbide testing is carried out in order to diagnose the presence of damp following inconclusive results or when previous findings by chartered building surveyors & damp proofing companies have conflicting results. There are several reasons why moisture meters can show high readings on the surface of a wall when diagnosing damp, which may include rising damp, penetrating damp, salt contamination, condensation and plumbing leaks etc. This is why a survey including this type of damp testing procedure must be carried out in conjunction with an external survey of the affected area to inspect for raised ground levels and any other sources of water ingress. The cause can also be determined from visual signs of damp internally and moisture patterns. Different causes of damp require varying treatments ranging widely in the amount of disruption and costs so the cause must be diagnosed correctly. Whilst in most cases the meter testing of walls and skirting boards and the recording of moisture profiles, together with internal and external surveys would bring you to the correct conclusion, the use of a speedy calcium carbide test would help in the diagnosis for any rising damp investigations.
This damp testing apparatus itself contains a sealed vessel that is thoroughly cleaned before each calcium carbide test is carried out; this prevents any discrepancies with the results and provides an accurate reading. A specialist damp surveyor will then drill a hole in the affected wall to obtain a measured sample of brick dust or plaster to test the moisture content.
Materials used in building construction do however differ in porosity and their ability to hold moisture, therefore it is not possible to take comparative readings using a calcium carbide meter from different materials. The BRE states in digest 245 “if moisture content (MC) is less than 5% at the base, it is unlikely that the wall structure is severely affected by rising damp” This 5% figure is merely a guide and refers to the base of the wall above damp proof course level. It does not suggest readings recorded above 5% are indicative of rising damp, it states the importance of testing HMC and MC, as some materials when contaminated with salt can be above 5% MC even when in a dry state. Moisture content readings from within the structure of the wall can be obtained in a few minutes.
Actual moisture content is determined rather than the Wood Moisture Equivalent (WME) readings displayed on a moisture meter. After testing samples, the cost of accurate diagnosis usually results in avoiding unnecessary cost on very disruptive chemically injected damp-proof course work, which usually results after obtaining unqualified advice from surveyors recording or reporting “evidence” of rising / penetrating dampness using inappropriate and misleading diagnostic damp testing methods.
“Diagnosing rising dampness in buildings needs careful and systematic thought because it can easily be confused with penetrating damp and condensation. The Building Research Establishment (BRE) have suggested that only 10% of the dampness problems it investigates are attributable to rising damp. Unfortunately, there are a number of damp-proofing companies specialising in d.p.c. replacement who obviously have a commercial interest in finding problems with rising damp.
The diagnosis needs to be treated with caution. Although there are several reputable companies working in this field, it may be wise to seek independent advice. Further “encouragement” to find problems of rising damp is provided by banks and building societies who often request a damp report as a condition of a mortgage advance, after high damp meter readings have been identified following a homebuyers survey.
“Investigations have revealed many instances in which systems intended to combat rising dampness have been installed in buildings where rising damp is not occurring, and where moisture meter readings found during a home inspection are at acceptable levels. A frequent reason for this has been a wrong interpretation of high readings obtained by using an electrical moisture meter”. Another reason is the failure to recognize other causes of damp conditions or the incorrect interpretation of results and analysis.
Property surveyors, who carry out inspections for building societies and homeowners, will check walls for dampness using an electrical conductance moisture meter most commonly manufactured by “Protimeter”. The electrical resistance meter assesses the level of moisture content in timber, this was the task it was designed for! In skilled hands, it can be used to determine the presence of moisture in other materials. However, it can only record the presence of surface moisture and is unable to determine the true moisture content existing in the underlying structural brickwork.