Small patches of damp on kitchen wall

[TheSalad]

Hi all, we have small patches of damp on the external wall in the kitchen. It’s in the place where previously the home’s boiler used to be. There is a chimney on the outside which now finishes in the loft space (bungalow). Roof and external brickwork are in good order and the chimney has an air brick for ventilation.

These patches appear stronger in the summer months when the heating is off and the air is humid.

Is it sufficient to take it back to brick, membrane and re plaster? Many thanks.

 

[foxhole]

The air brick is in a poor position , is the old chimney open in the loft space ? Or there will be no effective ventilation .

 

[TheSalad]

Hi, yes the old chimney is open in the loft space so there should be sufficient ventilation.

I now suspect cold/moisture bridging through dotdab. But I'm not sure how to fix it.