Loud Noise in rainwater pipes

[Cinnamon21]

Hi, I live in a 10 storey block of flats on the ground floor and inside some walls of my flat are rainwater pipes that run down from the roof. Couple of months ago I started hearing a loud bang in the walls where those RW pipes are hidden whenever it rains heavily. The building manager sent a plumber who put a camera down those pipes directly from my flat and then all the way down from the roof but claims there is no problem with the pipes so now I am not sure what could be causing the noise. I have managed to record the noise in the attached file. As I said it only happens when it rains heavily and usually I hear one bang when it starts raining and then nothing but when the rain intensifies or starts again I will hear the bang again. The plumber also said it could be caused by rain coming down heavily to the bottom of the pipe and causing the bang when it hits the bottom but I have lived in this flat for 8 years and have never had this issue before until this year. Also as a leaseholder I am responsible for pipes that specifically serve my flat and the housing association is responsible for
pipes that serve the whole building so now I am not sure if I need to keep pressure on the building management to get this fixed or is it something within my flat that is causing this ( although I am not sure how it could be caused by issues in the pipes inside my flat if it only happens when it rains).Any advise will be appreciated. thanks.

 

[Basher]

Given there has been an internal inspection that appeared satisfactory, I would hazard a guess that it's caused by thermal contraction of the pipe when cold rainwater suddenly washes down it, after the pipe has been kept warm from the flats. It may be happening at a clip where its supported, or there may be an expansion joint that 'sticks'.
I don't think it's a problem other than the annoyance factor for you.

 

[steadyon]

Don't see how a camera inspection of the insides of pipe will reveal any broken / missing clips, which could be a cause of the noises.

 

[WC1]

It has been known for building managers to send a contractor with the specific task of not finding any problems.

 

[Chuck]

My money is on slip-stick noise when the (warmish) pipe is cooled by rain. You need a combination of a period of hot weather followed by heavy rain. It probably happens on hot days. You also someone at home, e.g. during a lock down to hear it.

A diary recording the weather and when the 'bang' is heard will probably be able to confirm the cause.