Noise from Dormer window

[seema15]

I have had loft conversion done a few months ago with a large dormer window. When it rains there is very loud noise of rain falling on the roof. I suspect that water from the flat roof of the dormer is not coming out at the front where the gutter is but spilling from the side onto the main roof where it is hollow.
The wall for the dormer window on that side is not been built to continue with the party wall but built about a foot from it.
Is a guttering on that side going to help as now there is a plastic gutter in the front only with a drain pipe from it coming down to the main roofs gutter.
The noise is loud enough for somebody not to be able to sleep there and is even heard in the room below although it is fainter.

The property is built on a hill and that side where the noise comes from is towards the lower side. But i presume the builder would have made a level roof?

 

[freddiemercurystwin]

All loft conversion roofs are loud when it rains. It would be even louder of you had normal roof windows that would take the full force of any rain. Have you been outside with some binoculars when a good rain is occurring to try and see? Or a small mirror on a stick can be poked out the window to try and see.

Is the noise the general noise of rainfall falling on the roof or is it more random in keeping with rain falling over the edge of the dormer roof? If it has not gutters the roof should be designed to direct rainfall back to towards the main roof although this is difficult when a wind gets up.