3 weeks ago a damp course was done into a property that i recently renovated and new plaster and skirting was replaced, Today upon inspection of the property the skirting boards all the way around the ground level floors was covered in mould spores.
There is a very very good chance that you did not need a retrofit DPC.
Dampness affecting the internal parts of a house can be due to lots and lots of reasons such as high ground levels, overflowing / poor gutters / rainwater pipes, leaking services, old main supply, condensation etc.
In my many years as a Chartered Building Surveyor I have never had the need to recommend a chemical DPC (which I assume you have had installed).
If, for arguements sake the damp was due to say a defective lead watermain that has been saturating the wall, a DPC is installed and the internal parts re-plastered. The leaking water main will still be there and will still be saturating the floor joists and wall and the 'special' plaster will only be taken down to floor level. The guarantee will be only for the DPC injection and will not cover other forms of contributing damp,so you may findthe company will conveniently wiggle out of blame.
I hope this is of some use, even if I have assumed a lot.
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