Knocking/Tapping Noise After Running Dishwasher

[AOIS]

Hi All,

I wonder if anyone could advise a possible cause of a consistent knocking/tapping noise from when the dishwasher seems to empty? The noise seems to continue for about 10 minutes after the dishwasher has finished its cycle. From my understanding It's seems to be coming from the soil stack.

We have an ongoing issue with the soil stack pipe being boxed in tightly and consequently when hot water is released it is expanding and knocking on a joist. My understanding though is this is further up the stack on first floor level as the new noise seems to be coming from much lower down as is audioible from the ground floor. The original issue was present from day 1 (new build property) surly the same issue wouldn't suddenly develop from a different outlet?

Any help or advice appreciated.

Thanks

 

[zzzjim]

Try a hotter , cooler wash to test your theory ?
( the greens will have us using less hot on dishes ,but food is more greasy than clothes ! )