We have a house built in 1930, which has a flat roof at the rear above my 18 month old son's bedroom.
When we moved in we were told that there had been issues with leaks but that it had been fixed and had a guarantee.

See attached image of the current spots of damp - we can't be sure if these are from condensation inside (we have used humidifiers) or whether the roof may well be leaking again. As the spots seem to be coming from the joins, I would suggest that they're from a leak.

Can anyone tell by looking? Is there a sure fire way to know?

thanks,

What do you mean by "a flat roof?"

Flat roofs come in many different constructions and if you have a flat roof in good-quality standing seam copper construction or in heavy lead construction you may have a very good roof indeed. On the other hand, if you have a 1930s porous concrete slab with a splash of bituminous paint over it, or an almost flat timber deck with some cheap felt over it, you've got a disaster which is probably not even waiting to happen.


Why were you using humidifiers?
What is the current hygrometer reading of relative humidity? Hygrometers are only a couple of pounds to buy and a vital tool.
is the roof insulated and if so, how?
Are the walls insulated, and if so, how?
How is the external wall to roof joint constructed?
Does that part of the house have gutters?
Are they catching all the water that comes off the roof?
is the condensation more on the North and East sides than on the South and West sides?
Which are the exposed sides?


Looking at your pics the condensation seems to be at the top of the wall and edge of the ceiling. Some answers to all of the questions above would be a start.

John