condensation or damp

1888

was in my sons front upstairs bedroom yesterday when i noticed on his ceiling what looked like either damp or leak damage from roof, upon closer look it was a black candy floss like material which brushed off, it was in both front corners of his room about 10inch long.
recently bought the house.[6weeks] that had been left empty for almost a year and was told it could be just condensation as house was empty for so long.
realise not easy without seeing but any advice on whats best thing to do either way?
thanx

keystone

I would suggest condensation the cure for which is ventilation.

Cheers

David_Aldred

Hi 1888,
I suggest going up into the roof void and checking the roof void generally especially in the area of concern.

Obvious things to look for are daylight suggesting a defective roof covering, missing or inadequate areas of insulation leading to cold spots on the bedroom ceiling prone to condensation, damp debris upon the ceilings leaching into the plaster below contaminating it and condensation both within the roof void (requiring improved ventilation) and occupancy condensation within the room itself due to an imbalance of heating / ventilation / insulation.

Insulation upon ceilings should have at least 50mm air space on the cold side of the insulation between it and the roof covering above which is important to appreciate where the roof meets the ceilings at the eaves.

If the ceilings where they meet the walls at eaves are pitched (i.e. not horizontal) as they are in ssome houses please be mindful that this area is unlikely to be insulated from above (whereas the horizontal ceiling areas are likely to be) and therefore tends to be a cold spot prone to condensation. Insulating such areas is often difficult given there is only the depth of a rafter at such points (typically 75mm deep) and given the 50mm air space requirement above insulation this would only allow 25mm deep insulation to be fitted here compared with nearly a foot thick for mineral quilt elsewhere.

This being the case such areas are often easier to insulate from below with a rigid insulation fixed to plasterboard incorporating a vapour barrier.

If mould is present then clean it down before it establishes itself as it is the products of the mould growth that may impact upon the health of people within the house if susceptable to it. Hope this helps, kindest regards David Aldred Independent damp and timber surveyor.

ariba10

Read this.

http://www.harfordsonline.com/downloads/condensation%20info.pdf