... received our initial colour selections for the external bits from our designer. Still getting my head around all of her selections.
At the moment it's....
-surfmist for all the downpipes etc
My 2c. You don't want to make a feature out of the downpipe, so I'd recommend you use monument or something closer to the coach-house clay to use against the brick work, and pebble grey against the cladding.
Basically, blend them into the exterior color.
Our color consultant actually suggested it and I was relieved to see that it worked really well.
Knowing full well the exterior design is a mix of exterior materials could be a challenge though. I'd still recommend it even if it only worked on half the wall.