Any idea what causing these (damp?) spots

[londonmackam]

I've noticed some faint spots on my ceilings in my two rooms upstairs and wondered if anyone could shed any light.

The spots are in equal spacing on the walls, I've circled them in red on the photographs. The roof seems ok, apart from where one tile has come away as you can see in the photos and I've been in the loft and its dry in there and doesn't smell damp or musty at all.

Through my own fault I hadn't been properly ventilating the rooms which led to the back of the furniture having a little mould growing, could that possibly be the cause or more likely the roof?

Also if anyone is in the TW13 area and wants a job to come and fix the problem

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• londonmackam
• 12 Nov 2014
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• londonmackam
• 12 Nov 2014
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• londonmackam
• 12 Nov 2014
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• londonmackam
• 12 Nov 2014
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• londonmackam
• 12 Nov 2014
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• londonmackam
• 12 Nov 2014
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• londonmackam
• 12 Nov 2014
• 1

 

[footprints]

My guess is they might be nail heads that are rusting, not galvanized type.

 

[JohnD]

there appears to be no insulation, so the ceiling and nails will get very cold, which will encourage condensation and possibly rust. If it is just a dark mark, it will be from the condensation and dirt. If it is rust, you can paint over with oil-based primer to seal it, then emulsion over that.