I live in an old 19th century shopfront house that shares walls on either side with other properties, thus it is impossible to check the exterior wall. I want to ventilate the walls, and drill a series of holes to allow the old mortar and bricks to breathe. Is this advisable? I have a dehumidifier that helps somewhat, but the damp still tends to appear in specific places. I live in the tropical south of China. Would it work to install a series of small holes in the wall that only penetrate half way through the wall with small extractor fans on each hole? I don't want to drill into next-door.