damp on first floor chimney breast

[cartertim]

hi,

i recently purchased a 1930s detached 2 storey house of cavity wall brick construction. The ground floor seems to be dry as a bone but we have damp staining on the first floor chimney breast at around ceiling level. It is not wet but damp/sticky to the touch.

the pointing to the chimney stack is sound as is the lead flashing. externally it looks as if the area around the stack has been re-rendered at some point historically but i am not sure why or when. Additionally, there is no sign of a leak in the eaves above the ceiling so i am at a bit of a loss.

the fire place at 1st floors level has been sealed up but there is no aur-vent/brick internally on the stack. would this be a potential cause of condensation and damp penetration?

the breast and ceiling have backing paper on them which feels damp and the paper paste is sticky to touch. upon removing the paper at ceiling height there is a lot of salting or efflorescence underneath. could this be hygroscopic chimney salting? any ideas how to eradicate permanantly if it is?

Any advice or help would be greatly appreciated.

Thanks

[welsh brickie]

a condensation build up inside the bresting will cause damp to show through,installing a plastic hit and miss vent should create enough airflow to stop it.

[cartertim]

Thanks for your response. should the vent be installed internally in the bedroom? at floor or ceiling level?
cheers

[cartertim]

Thank you. should the vent be installed and floor or ceiling level?

cheers

[welsh brickie]

it should be installed in the breast wall about 600mm from the floor