Sloping cold / mouldy ceilings - should we try not venting the soffits ?

28 Nov 2018
Reaction score
United Kingdom
Hi Everyone, we have a 50's ex council house - the bedrooms have slightly sloping ceilings due to the roofline.

we have had lots of issues with cold rooms and mould on the inside of the bedrooms, along and on the sloping part of the ceiling - we are trying to insulate down the gap at the moment hoping that will help. The main problem seems to be the warm air in the house hitting a freezing cold slope.

We are having new soffits and we have a choice as to whether to vent or not, it is currently vented however the guys on the roof says the air just goes onto a cemented ridge so they aren't venting well just making the air cold in that area.

I have also heard research to say that if we don't vent it may solve the cold slope problem, of course others will say if we don't vent we will rot the roof.

be grateful to know your experience and suggestions

Thanks so much
Sponsored Links
Hi yes, tend to have windows open when possible and rooms have airbricks
this thread is a bit like the post thread next to it in the roofin forum called "roofin tiles".
if you dont already have insulation fixed between the rafters then no more ventilation at the soffits needed.
what they call natural ventilation will come from the roof itself.
so insulate the sloping roof area.
Sponsored Links
Hi, yes we are going to try and insulate the sloping area but it seems like the only option is to drop downs some kingspan - trying to cover all bases to try and solve the issue.
Hi everyone, would be good to get your thoughts on this - we decided not to add the extra vents and the loft is very airy and breezy, not ofthe other neighbours have had a problem.

However one week after soffits replaced some sticky residue drops / water marks have started trickling down the wall - is this a leaky roof, soffits issue or condensation ?

No recent painting done to room, no-one smokes etc

It's no good venting the roof/back of the ceiling as all this does is make the ceiling cold and increase the conversation risk.

What you should have done whilst the work was going on and the scaffold up, is take the tiles off roll the felt back and fill the gap between the rafters with celotex.

Now you'll need to line the underside with insulation instead.

And you could try dealing with the moisture you are producing at source, or changing the home heating and ventilation patterns.
Hi thanks for reply, Husband has got some kingspan he is going to try and slide down the slope as soon as he has some time. In the meantime we are trying everything, inc, new window.

The door is left open all day and i crack open the window as often as possible.

These drips, see photos have occurred a few days after new soffits fitted - is that condensation
or leak do you think ?

Not sure if i can change my lifestyle?
I'd look at packing some rockwool into the void rather than dropping some celotex type foam in. You really want the insulation in contact with the topside of the ceiling where you're getting the cold spots.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links