Gap between roof tiles where next property meets

[armibewo]

Hoping someone can help me with this.

I've recently had some work done on a chimney I share with the next property (replacing missing mortar). However in the video I've been sent showing me the work I've noticed there is a sizable gap between my roof tiles and my neighbours (his roof was redone many years ago).

Is this likely to be a problem in terms of water ingress?

 

[johnny2007]

There's probably a joining tray (don't know if it's correct name) under the tiles.
Basically it's a sheet of fibreglass or plastic with ridges, making water drip down to the gutter.

 

[armibewo]

OK that makes sense Thanks.

 

[armibewo]

Sorry to come back to this, I've struggled to find much online about bonding gutters (other than where to buy them).

My question is, is there usually any maintenance required on bonding gutters over time? For example can they become blocked? I know some types are meant to have mortar under the tiles, would that ever need touching up?

As a bit of background, the reason we've had the chimney looked at is because we are getting a small damp patch on the chimney breast / party wall. The chimney work has not stopped the water ingress so I'm looking at alternative sources of the problem.