Sandberg Remains Open During This Challenging Time

Whilst many of our staff are working from home during these unprecedented times, all our activities remain open for business in line with government guidelines.  We have adjusted our operations so that staff remain safe.  Currently, although we are working at a reduced capacity, we are meeting client demands and are welcoming new enquiries.

Waterproof membranes

Typically, faults with waterproof membranes may be initially explored with water sample analysis in order to provide initial indication of the source of leaks.  Methods of testing waterproof membranes undertaken by Sandberg often comprise the following methods:

Electronic Leak Detection

A more comprehensive survey of the roof membrane can be undertaken using electronic leak detection equipment. This is undertaken on roof membranes clear of overlying materials to be tested for leaks. The integrity of the waterproof membrane will be checked/inspected using purpose built leak detection equipment.  The test process involves locating earthing points within an electrical field created on the membrane surface. 

In one method, the electrical field is created by passing current pulses through a loop of wire laid around the perimeter of the area under investigation which is wetted during the test.  Electrical current flows towards any earthing point.  The direction of current flow is identified using a pair of probes and a purpose built detector unit.  Each earthing point represents an electrically conductive penetration through the waterproofing layer and is a location where water ingress may occur.

A second method, carried out dry, uses a high voltage to check for earthing points in the membrane being examined.

Moisture Meter(s)

Site surveys can include the use of a moisture meter to identify areas of moisture under waterproof roof membranes and, by adjustment of the instruments sensitivity with respect to the conditions being surveyed, may also detect relative concentrations of moisture.

Chemical Tracers and Dyes

Certain instances of water penetration creating leaks may be possibly investigated by applying  chemical tracers and/or dyes.  The purpose of such applications is to typically verify or bring focus to the likely source of the leak.


These are applied in situations where they may assist the identification of leaks; they are often limited by damage caused to decorative finishes, dilution effects and discernability (dirty water from the leak).  The merits and disadvantages are always assessed during the course of any investigation works.

In situations where water penetration only results in staining, a florescent dye is sometimes deployed.  The principal benefit is that with this type of dye only a small amount penetrating can be detected using an ultra violet light source.

Optical Inspections

The use of a borescope or videoscope enables inspection of inaccessible areas and where access is  limited.  Disruption is kept to a minimum as only a small access hole is required to permit access for the viewing probe. These prove useful to expand observations when sourcing leaks in certain situations.

Bob Easthope

For further information contact: Bob Easthope, Senior Associate
Direct Tel: 020 7565 7064
Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

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