I have recently moved into a house which has a slight problem with condensation in the loft space. The house is detached and was built in 1976. The original wooden facsia and sofits appear to have been replaced a couple of years ago with white upvc which is sealed and has no ventilation. This was highlighted in our building survey as the likely cause of the condensation. The sofits are tongue and groove effect and I can cut out holes in these to insert 70mm round venting discs. The house is rectangular in shape about 12.5 Meters X 8.2 Meters with a conventional tiled roof. I just have a couple of questions which I'm hoping someone can answer.
1) Should I insert these discs on all four sides or just the two longest sides in order to get a cross flow of air ? - Is it possible to over ventilate the loft ?
2) How far apart should I space the venting discs ?
I would be greatful for any advice