This is a ‘backstop’ to check for any materials released as the enclosure is taken down. It’s possible they were trapped within the folds of the enclosure material for example.
The analyst will check the more general work for any residual problems, including a revisit of the transit and waste routes.
Minor issues can normally be cleaned easily before the fourth stage is completed, but in extreme (and very rare) cases, the enclosure may need to be reinstated and the work will need to be redone.
Once all four stages are complete, and only after the fourth stage is signed off, a certificate of reoccupation is issued.
Note that further testing works associated with asbestos removal may be required and we can assist you with leak testing, personal sampling and pre-start background tests.