Condensation in loft space despite vent tiles Information, help and tips on many areas of roofing including trusses, tiling, venting, insulation etc....

[elliotdavis10]

In our loft space (1930s end terrace - moved in approx August 2020) I've got black plastic inside the battens under the tiles instead of felt. Its a t-shaped loft space approx 6-7metres in each direction max.
In between each roof joist is a lot of condensation. There are about 4 vent tiles up there and it's pretty cold with what feels like lots of air flowing about. But the stuff I'm storing there is getting very damp and there are drips literally running down inside the plastic sheets. At certain points round the vents where it has been cut, there are drips falling off the sharper points of the cut plastic.
We don't have anything venting into the loft space like bathroom extractor etc.
All the vents are fairly low down but even around them there is condensation. I will attach photos.

My question is, do I add a whole load more vent tiles, and if so where should I put them? Or is there a different problem? I'm worried about getting out roofers who i don't know and might recommend something not necessary.

Thanks in advance. If there's more info I need to post just let me know.

[stoneyboy]

Hi elliotdavis10
Assuming your vents are clear and there are the equivalent of 60sqcm open on each side of your roof, ventilation is unlikely to be the issue.
When you moved in had central heating been freshly installed? If yes this may be your property drying out.
Regards S

[elliotdavis10]

Hi Stoneyboy, thanks for your reply, that's helpful.
The house was empty for quite a while and then we were renovating for a while which involved new central heating, and points in time when the side and back of the house was open and obviously will have got it very wet.
With regards the 60sq cm space round the vents, they are between the roof joists and obviously roughly half way but one or two a little close to one side more than the other, but otherwise aren't obstructed in any way.
I've got a dehumidifier running up there non stop for the last few days and have been up and wiping/drying down the black plastic with towels to dry it off as best I can. But the dehumidifier isn't making much difference yet and the condensation just returns.
I'm wondering if anyone has any further advice. I'm worried the roof joists that the plastic is sitting on is getting mould starting to grow on it in places.
I'm now tempted to buy a second dehumidifier and have two running non stop.
Thanks in advance.