Mould and Condensation

[BB10]

I have recently built a holiday house on the South Coast of NSW.
Towards the end of last summer I had finished the downstairs storage, laundry, bathroom and had noticed after installing the fridge we had a large amount of furry mould start growing in certain areas. After cleaning and relocating the fridge to upstairs the problem seemed to be solved.
I have had the room waterproofed internally and externally but it is on the south side of the house with little air movement from the outside. I now have the problem of condensation on the tiles to about 300mm from the floor. The toilet also has condensation. This condensation is now collecting on the tiled floor and a black spotted mould growing.
My thoughts are that the humidity from the outside is entering the window and condensating on the cold tiles and toilet. I do not think it is moisture tracking through the external walls. Should I install an in line duct fan on timer to get the air moving or be sucking fresh air from the outside. Any ideas greatly appreciated.
Regards,

Brett

[wonderplumb]

Sounds like its drawing moisture from the ground around it, is the bottom floor dug in to the earth at all??

[BB10]

The slab was laid on black plastic. All the external walls were painted with a bitumen paint and internall walls waterproofed. Only half of one wall has gravell against it and this has aggy line to take away the water.

BB

[elkangorito]

The problem is that you have "waterproofed" the area. I suggest you do some research into "vapour barriers" & "vapour blocks". Increased airflow should solve the problem.