Got a small roof on the bck of my flat which seems to be leaking,had a quick look at roof at cant see any damage but over time it started to come though ceiling but mark is not really wet to touch.
Have put some pics to shown damage so need some advise what course of action to take as new to this.
Water is coming through the roof and it is making its way through the joins in the plasterboard ceiling.
Get up in the loft with a bright light and take a look and some more photos of the wet rafters and the top of the plasterboard.
Note: Water can travel quite a long way before it shows itself, so look carefully, water usually makes its way downwards but, wind blown rain does travel up hill as well.
I hope you have sorted but if not.
the loft option reply is no good as the question is related to the extension roof.
I notice your facia has a around a 6 inch stand off so. check for ventilation holes or in some long vent slots ensure they are clear. If not vented see below.
1. Bad ventilation of the roof cause damp build up due to no air flow.
2. Cracked tile but if the roof is felted the felt should channel water down and into the gutter look for roof flet tail ending the gutter. Felt is fine until this type of situation where you can only access roof void from outside
As for venting the roof check at your local builders merchant for suitable products to install in the facia [means removing gutter.] and the side wall which would be an air brick but one with insect mesh or you'll have wasps making a nest in the roof.
it looks quite an old extension sounds like the felt could be perished which means water does not get to the gutter (a simple eve guard will solve this) which also means water is getting under the tile this could be your lead flashing that is damaged or simply a cracked tile
I have faced the same problem few yrs. back ,I have used the ultimate linings UL 61A
Self-Leveling Polyurea Polyurethane
Caulking Compound product for water roofing and leakage purpose.It is used on interior concrete surfaces, to repair random cracks, control joints, and other areas where down time is limited.