having moved into a first/second floor flat over the summer, we didn't notice any problems with the building, and were told that the estate agent had done a building survey. now as winter is taking hold there's some problems arising.
it seems half the flat is a recent extension, and the other half part of the original building. the newer half is colder, and damp, despite having the same heating and the same windows. condensation forms on the windows in the newer half, often pooling on the windowsill, causing mould to grow on the bamboo blinds if you don't keep up with wiping it all down (there are also curtains - not sure if that's helpful or not). the room where this is worst also has bubbling beneath the paintwork; various sizes of bubbles that either burst and break the paint and then drip water, or just get bigger. the paintwork around the plaster frames of the windows is flaking, and feels cold and damp to the touch. in areas where the paint has flaked off, some white fluffy mould has started to grow. after worrying about the effect the damp might have on low-ventilation areas in the room i moved everything and looked behind. i found little effect, but one corner had water streaks and black mould growth. this is close to an electric socket - does it create a hazard?
the connecting wall between the old and new parts of the building is also affected. the wallpaper in this part has cracked, started to fall away and in some parts turned orange and bubbly. the whole wall feels cold to the touch, and just yesterday i noticed a small cream/yellow mushroom-like fungus growing out of a wallpaper crack. the opposite side of this wall coincides with the corner of a smaller room, where there is black spot mould growth. this is where i first saw signs of mould growth and used an anti-fungicidal spray to get rid of it, but after a while it came back.
i have spoken to my estate agent about it, from the start when signs first arose. they were happy for me to use a spray, and sent out their builder to inspect the building. he spent some time on the roof, and apparently did some work on it but to little effect.
my question would be whether getting a dehumidifier will help? after doing some research it does seem like the flat has high humidity in some parts.
there does also seem a need for some more building repair, but i'm unsure of the costs that my landlady would be facing and reluctant to go out and get quotes for us/her with having little experience in the area. obviously it would help to upgrade the windows to double glazed, but i know this can be pricey.
is there anything i can do in the meantime to lessen the effect of the damp and cold?
is a dehumidifier with a warm air outlet a good way to lower humidity while improving the heat of the room?
is the cream/yellow fungi harmful?