Mould spots on new plaster boards, condensation or something more serious?

chickendipperbabe

Hi, just a quick question regarding black mould.

We’ve recently had a conservatory re-built, it’s an Orangery type with lots of brickwork (insulated brick and block cavity wall) and pelmet.

We’ve recently come to decorate it and noticed a couple of things.

Firstly the plaster board has mould spots on it in certain places. There are no mould spots on the plaster skim itself, just the bare grey paper boards at the bottom near the floor where they haven’t been skimmed (where the skirting board will be fitted) The mould itself appears dry and simply wipes off like dust – The mould spots seem to be confined to the surface (one side) of the paper covering on the board, it hasn’t penetrated through to the other side of the paper.

Secondly upon noticing the mould I had a feel around the base of the walls and noticed that the floor was damp on both exterior corners, putting my fingers up behind the plaster board I found that the block walls were damp.

At this point the humidity was in the high 70’s low 80’s constantly – we had been heating it with an electric radiator and leaving the windows on night lock though I think this my have been inadequate for the plaster drying out as well as other parts of the base still drying out.

As a side note, we had issues with the plaster work and some of it had to be removed and replaced, the whole interior was also re-skimmed and there was a week or so where the room was sealed up tight with plastic covering all windows meaning no ventilation, its basically been plastered twice in the space of a month.

The mould that’s been wiped off hasn’t come back and humidity is down to the high 50’s low 60’s but I’m still occasionally finding the walls damp when I put my hand up behind the plaster boards but not to the extremes they were when I first noticed it. The conservatory is still not finished and is unused, it’s been kept at between 10* and 15*c – bare floors and no skirting boards fitted.

Is this something to be worried about? I don’t think the damp walls are due to a leak as it’s also apparent during dry cold days and in more than one spot. Would I be right to assume the issues above could be down to condensation? Warmer humid air entering where the skirting boards are to be fitted, travelling up the gap and condensing on the cooler block wall behind the plaster?