condensation or leak

[need2learn]

I moved into my house 2 years ago. everything fine. Then after a time probably 6 months a damp stains appeared at the apex of the vaulted ceiling. (exterior Chimney) I assumed no problem Flashing. I have spent £000,s on having Chimey pointd, tiles lifted and checked, ridge tiles lifted and re set. finally sprayed with Johnson seal liquid. Builders say pull down and rebuild the chimney or was it pull down and rebuild house. Recently I thought to check with damp people instead. They are all flummoxed except one chap says it is condensation hitting the cold wall where chimney is.
Any ideas please.
newish house built 1985. good condition. double glazed There is an oldish gas fire in fireplace.

 

[JohnD]

photos please

what colour is the stain?

How is the roof insulated?

How is the chimney ventilated?

What is the room used for? How is it ventilated?

Does anyone drape wet washing around the house or over radiators (need not be in this room)?

Tape a piece of clear plastic tightly to this wet patch. Tomorrow, tell us which side of the plastic is wet.

 

[theprinceofdarkness]

Long term condensation results in a black spotty mould. If its a stain I would think its some form of penetrating damp. Also the ceiling is the hottest part of the room though corners (where there is no air movement can suffer from condensation).
Tell us more about this chimney breast. Is the fire in use?, is the pot capped and the flue ventilated?
One thing that people neglect is the fact that the flue is a good loss of heat, so I have on unused but open flues is to push a big wadge of glass fibre (in a plastic bag) up the flue to be level with the loft insulation. this reduces the air flow and hence the heat loss. In your case it would allow the chimney breast to be warmer, and hence less prone to condensation.
Frank

 

[need2learn]

Many thanks for your help and advice. I shall be dealing with them later tonight and photos etc