Cupboards by external walls are prone to mould as vapour moves through diffusion, but heat moves mainly through air currents. Humid air become trapped for hours. Mould needs long term high relative humidity to grow, 6 or more hours at 85%RH.
Insulate between cupboard
Insulate cold water pipes. Install insulation around cold water pipes such as in the kitchen.
Insulate old buildings.
Insulation. Consider installing such as thermal insulating plasterboard, thermal lining paper, such as wallrock thermal liner or Sempatap thermal solid wall insulation to cold surfaces – check fire regulations and manufacturer compliance.
Loft insulation. Consider adding to the loft insulation, making sure to distribute it evenly, making sure to insulate the eaves, without stopping air flow and loft ventilation.
RSJs are prone to condensation as the metal is normally in contact with the cold external temperatures, either supporting an external wall, adjoing wall or in contact with the sub-floor void or cold ground. Metal loses heat rapidly when there is a relatively large heat difference between the inside and out.