Condensation in new build loft

[Welsh_Imp]

Hi everyone, hopefully someone can give me some advice.

My wife and I recently purchased a new build home from David Wilson, we got it at the end of last year just as the snow came.
We've had a few small snags and so on but nothing major...apart from one thing.
Our house is a 2 and 1/2 story house. Basically we have a very small loft space due to the master bedroom and ensuite being on the top floor.
About two weeks after we moved in we noticed brown staining on the ceiling of the master bedroom and a sound coming from the loft hatch. Upon opening the loft hatch I was greeted with a wall of water. The condensation up there was so bad it was like a rain forest. All the felt on the roof was just covered in drips.
Wilsons came round a few days later and put some de-humidifiers in. That seemed to solve the problem and Wilsons blamed the condensation on the 'adverse weather'. This appeared a bit odd to me as to be fair it gets cold in Britain every year, but I bought it as the roof was covered in ice and snow for about 4 weeks and I thought warm air just might not be able to escape.
Over the past 3-4 days, and due to the warming weather, I've turned the dehumidifier off and closed the loft hatch. I looked up there yesterday and patches of condensation were forming again, not all over the roof, but in several places. Wilsons had a look and said "that's quite normal, and it's still cold" - although the snow has been off the roof for about 2 1/2 weeks. Wilsons have said it's sorted and are going to take the de-humidifier out but I'm really dubious about it all. They've said they put in an extra air vent up there, but again I'm not unconvinced they're telling porkies.

Does anyone know if this sort and severity of condensation is normal? What could be causing it? And what should we tell Wilson's to do? We're getting quite worried and are thinking about getting a roofer in to do an inspection because we don't want this developing into a more serious problem.

Sorry for the long story - but any advice would be really gratefully received.

[stoneyboy]

Welsh_Imp,
The most likely cause of the condensation problem is your new home drying out. Suggest to DW that you keep the de-humidifier for now - keep it running until the weather gets warmer.
end

[Welsh_Imp]

Thanks Stoney_Boy,

Have spoken to the builders and recommended we keep the de-humidifier for the time being. To be fair to them they have been pretty good.

I think a combination of no knowledge of building and too many 'ITV - homes from hell' probably worried us a bit too much.

Thanks again.

[welsh brickie]

I would check to see if the insulation is blocking the eaves there must be airflow in the loft .
try pulling back the insulation from the edges of the floor.