JW Surveys

Have you been told you have “damp” but not why?

Those who stop at the symptoms do not care about you or your house – they want to sell you their products and move on. They have absolutely no interest in fixing any defect for you, they mask the issues and hope you never have to claim their warranty or guarantee to repair it again.

JWSurveys Ltd carry out damp surveys on all types of properties from modern buildings to a wide range of historic listed and un-listed buildings of varying age and construction. We understand how buildings function and the importance of using traditional materials that are compatible with the building fabric.

Important Note on Electronic Moisture Meters

Hand-held electronic moisture meters, often referred to as damp meters, are not capable of accurately determining the moisture content of the masonry and are calibrated to be used only on clean, untreated timber as stated in British Standards BS 6576 and BS 5250. They are calibrated within the range of 8-28% moisture content. Readings below or above this are meaningless.

Our surveys are all conducted in accordance with the guidelines contained within

• BS 7913: – Guide to the Conservation of Historic Buildings (British Standard)
• BS 6576: – Code of practice for diagnosing rising damp in walls of buildings
• BS 5205: – Code of Practice for control of condensation in buildings

Out of the hundreds and hundreds of buildings we have surveyed, we have never once found a true case of ‘rising damp’ or the need to inject a chemical damp proof course. Similarly, we have never found a case where timber preservative treatment is required.

Where appropriate we use the following methodology

• Calcium carbide meters to chemically test drilled samples of masonry to establish the total moisture content of a material. Carbide testing is the definitive on-site method of testing for dampness. (These tests are not undertaken prior to purchase surveys without written authorisation from the property owner.)
• Thermo-hygrometers to measure ambient humidity to assess any impact this is having on the fabric of the building
• FLIR thermal imaging cameras to analyse areas where there is cold bridging which may indicate water leaks, and thermal changes in masonry indicating trapped moisture.
• On-site salt analysis to detect the presence of hygroscopic salts.

What is a calcium carbide test?

A speedy carbide test is an item of apparatus used by damp specialists to determine the moisture content within a damp wall. It involves drilling a small hole into the wall and taking a sample of masonry to evaluate its total moisture content. The test aids surveyors when investigating a property for damp and helps to determine an accurate diagnosis of the dampness within the property. We do not “make good” to the drilled hole after.