I think this was the problem as to why it was blocking too easily.
Plus moss from the roof means there's a risk of big clumps.
Now I'm thinking about it I should have got him to buy some sort of cover for the top of the down pipe.... Although that may just result in water collecting.
Here mine , can get blocked up as there is a pipe at the bottom with tight bend that heads off to main drain running along side of house . Splashes up and wets wall when the rain is heavy so not sure I would recommend
I think this was the problem as to why it was blocking too easily.
Plus moss from the roof means there's a risk of big clumps.
Now I'm thinking about it I should have got him to buy some sort of cover for the top of the down pipe.... Although that may just result in water collecting.