Are the damp meters reliable and are PIV worth it?

Damp meters are about as useful as chocolate fire gaurds if that is what your relying on, depending on what type of mould will depend on the solution from better ventilation to discovering if there is a leak somewhere that needs fixed, rising damp is about is rare mostly misdiagnosed as some other form of water ingress, sound like your surveyor wants to sell you a piv unit and a damp proof course I will bet he just happens to know someone who can supply your needs. Good luck Alex

True answer from the other builder comment, it’s like having a block drain , 90 % you can clear a drain with drain rods , calling a drainage engineer out with jetter , the money start printing from £ 75 for half hour , imagine there around for 2 hrs ? Not bad money , with damp it’s rather low rise or high rise , a winter issue, heating , drying , ventilation especially kitchen area and bathrooms , what’s going outside on ground, damp course to low or path to high water running back to wall , air bricks installed, grass against the front wall , installing French drain ( single ) on grass