Do I need a damp expert or builder I have damp from ceiling to wall coming down it seems worse when raining outside. I need some one who can determine cause

first thing i would check is the brickwork to see if the pointing is ok, then the roof to see that there is nothing wrong there, and i would get a general builder in to diagnoise the problem. hope this helps alex

Have you checked your gutters are not blocked this would be the first and cheapest place to look, next time it rains get outside and see if any gutters are not coping with the rain fall properly its easy to see if not get someone to have a look. then you may need to check the walls and the pointing etc pick the easy solution first and then the expensive ones after hope this helps if so hit the like button Kelvin In addition if it is condensation some problems are not helped by using vinyl silk or gloss type paints on walls the result can be moisture building up and the walls not being able to breath properly and black mould appearing on the surface, lack of good ventilation in bathrooms and kitchens such as extract fans to outside, Recirculating kitchen extracts do not remove moisture, drying clothing inside is another problem, most tumble dryers need to vent outside any steam/water in the air within the house will condensate on cold walls and often on windows. Although you have a new roof and gutters still check when it is raining that no water is coming over the gutters and that the joints are not leaking and the fall is working correctly new does not always mean it actually works correctly. hope this helps Kelvin

Probably best to get a damp specialist out.

My answer would be long so , google hygroscopic dampness and ammonia sulphate contamination to chimneys. The most misdiagnosed damp condition in chimneys . It might look like rain is wetting it but more often than not it’s hygroscopic dampness .