It is not uncommon to find a termite nest under a patio eating on the old timber form-work. A lot of termite inspectors forget that this is a high risk area and make the mistake of not investigating if there is a cavity under concrete patios attached to a house. The house might have an infestation of live termites and they will recommend a treatment to the external perimeter thinking it will stop the termites. Unbeknown to them, the nest is inside and not treated at all.
This was the situation found at a house we recently inspected in Brisbane. One of our Senior technician, David Bell, was concerned about this possibility and drilled a small 12mm hole through the side of a concrete block patio. This allow David to insert a bore-scope to check inside the cavity where he quickly identified a large amount of termite workings. With the permission of the homeowner, David cut an opening through the blocks to allow access to treat. If David wasn’t thorough with his inspection, this nest would have gone undetected and untreated.