I have often wondered if one can claim when a tradesman makes a mistake years latter when found?
The problem is to prove who did it, and also show why it was not reported earlier, with electrics we should have an EICR done every 10 years, so finding an electrical fault 8 years after it was done is reasonable, but 12 years after, the question is why it was not found when the EICR was done, and is it the person who did the bad workmanship, or the inspector who missed it?
There have been cases where the wrong floor boarding was used, and bed legs have gone through the floor, the house normally has a 25 year guarantee, but it could be much longer before a bed with 4 legs rather and 8 legs is used and the floor fails.
And as to an EICR it is only the electrical condition which is reported, the BS 7671 says "Unless otherwise recommended by the manufacturer, a small spotlight or projector shall be installed at the following minimum distance from combustible materials:
(i) Rating up to 100 W 0.5 m"
If going by that rule, one has to ask where down lights can be fitted, wooden beams are often less than a meter apart, and ceiling to floor boards of room above often less than ½ a meter. But we seldom retain the manufactures information, so how do you know the manufacturer has not said it can be fitted closer? And with a 3.5 watt LED clearly there is not that much heat. And an EICR has to report danger and potential danger from electricity, the inspector has not got the skill to say if there is a danger of structural failure.
As to house insurance, I know they questioned who had done the plumbing when a pipe disconnected, lucky for me it was the guy the insurance employed to correct a previous fault, he had missed out a serrated washer. As to if the insurance would fight the case when a tradesman makes an error I don't know.
I have many times wondered if I could be taken to court for errors, I remember being told to stick some earth wires onto some meters and through a hole so any inspector would think earthed, likely 30 odd years ago, and I did as told, the idea was we would return to fix, but the guy went to the wall, so no idea if actually ever done.
Since I did not complete the EIC there is no real way anyone would know it was me, it was well before Part P came in, and it may have been corrected as intended. But cutting a lump out of a RSJ is not some thing one would come back to correct, but how do you find out who did it?