<ul><li>2 no. engineers to attend site and carry out a tracer gas survey which involves pressuring a harmless mixture of Hydrogen and Nitrogen gas into the underside of the roof construction.&nbsp; The Nitrogen is used as a carrier for the Hydrogen molecules which will gradually rise and permeate through the roof construction in the&nbsp;area(s) of leakage.</li><li>The engineer will use electronic detection equipment at the roof surface to vacuum and locate the Hydrogen molecules as they escape and the suspected areas of leakage are then recorded within the final report.&nbsp;</li><li>Site to be left clean and tidy.</li></ul><p>Our total cost to carry out the above works out of normal working hours shall be</p>