Locating leaks

As well as the calibrated test equipment used in measuring the airflow through the building, there is a range of ancillary equipment that a testing organisation will probably use when testing a building, and particularly when investigating leakage after an unsatisfactory initial test.

Although the back of one’s hand is often completely adequate for tracking down leakage sites in more leaky buildings, leakage rates can be so low in Passivhaus projects that it becomes unreliable. Even the more sensitive human eyeball cannot always be relied upon, hence we use chemical smoke, thermographic cameras and extending vane anemometers when searching for leakage.

Another common tactic is to fix a square metre section of polythene or similar membrane over the surface of a wall that we suspect is leaking. Under de-pressurisation, if the membrane bulges into the property, there is clearly a leak through that wall construction. A common gross leak that we routinely find is through door locks, even in very expensive Passivhaus certified doors.

Where dwellings commonly leak

This diagram illustrates many of the leakage sites that have been found in new and existing housing. One key point to remember is that wherever there are voids, there is the potential for complex connecting air paths to form, allowing leakage to occur in some very surprising locations.

1. Around floor joists

2. Beneath windows sills

3. Around windows

4. Around doors

5. Beneath door threshold

6. At edges of suspended floors

7. Between floorboards

8. Loft hatches

9. At eaves

10. Around roofl ights

11. Behind drylining

12. Through poor masonry

13. Via meter boxes

14. Around and through electrical sockets, etc.

15. Around boiler flue

16. Plumbing to bath

17. Around waste from WC

18. Kitchen waste

19. Around radiator pipes

20. Around spotlights

21. At base of soil vent pipe

22. At top of soil vent pipe

23. Around duct connections through ceiling

24. Around pipe connections to tanks in unheated loft

25. Around tumble drier vent

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