HELP mystery smell - condensation in loft?

[condensationnightmare]

A few weeks ago a mystery smell developed in our daughter’s nursery (not yet sleeping in there but was meant to be moving in there asap

It’s a damp earthy smell. It’s not foul/horrible so I’m not thinking drains/dead animal or anything like that. I’m thinking more like mould/damp. It’s getting stronger by the day.

Any ideas please?

We have deep cleaned the room and found no visible issues except for a subtle outline of the plasterboard appearing on parts of the ceiling. It’s a new build house (6 years old). The smell is strongest at head height and in middle of the room under the bedroom light.

We have so far concluded that it must be coming from the loft that we had boarded a year ago (by a joiner who was doing other work, not a specialist)

Upon inspection he has left no space for air flow and has put boards straight down onto the joists (we’ve since learnt he should have added additional joints first to create a gap to allow air flow). He did remove a bit of insulation to try create a gap/airflow, but then threw this into the eaves in a pile and just left it there. Apparently this is also terrible for airflow.
A loft specialist has come out to inspect and he believes we have probably found the source of the smell but can't be sure. He partially lifted a board and found the insulation underneath (and the underside of the board) to be moist but not soaking.
We have arranged to have him remove and replace it ASAP. He has been very honest and genuine and was initially saying although it’s not best practice we could probably leave the boards as they were, but then he changed his mind when he felt the moisture. So I do believe the work needs doing and this guy comes highly recommended.

We have also asked him to remove and replace the insulation but not sure if this is OTT? He think this might be overkill, but our thoughts are: it may have mould in it now and may continue to smell, so while the boards are up - best to get rid of it?

So my questions are:

Have anyone experienced anything like this?

Is replacing the insulation overkill?

Do you think replacing the boarding and the insulation will eradicate the smell? Do you think we have found the source?

May we also need to replace the ceiling in the bedroom? Just thinking with the smell being so strong in the bedroom, the plasterboard used for the ceiling must be really damp/smelly also now. Will it dry out?

Any wisdom, tips, ideas or experience appreciated

Thank you

I think you don’t have sufficient ventilation. Warm air from your house is going into the insulated loft area and is turning into condensation as it hits the cold boards. Yes. Increase the joists and create an air gap. External air brick might help too. A ceiling repair might be helpful. It might go mouldy which you won’t want. Replace insulation. I don’t see how it can dry out. Don’t put any more down until whole area is dry. Our loft floor is on legs to create a gap. This will also work. Make sure your roof vents are sufficient too. In the tiles and insulation in the actual roof.

Thank you for your reply

How long do you think we would need to leave the area to dry before re boarding?

And would it just dry over time or would we need to put a dehumidifier up in the loft?

In an ideal world we wouldn't do any of that as massive hassle but of course we will if needed.

We have also bought some of these plastic vents to add to the felt roof which are apparently great for air flow.

We're going to be much more mindful of lifestyle factors in the house

You can get a moisture meter. I would get one and make sure it’s dry. Not sure how long it would take. Obviously quicker if you dehumidify the area and ventilate. Taking the insulation out will be a horrible job. But necessary.

We have ventilated our roof with the inserts you have but you must ventilate between the ceiling and the loft floor.

Thank you
When you say ventilate between the ceiling and the loft floor, do you mean by leaving a gap next time it's boarded, or is there something else we need to be doing?

Bump - anyone else any experience with this? 🙏🏼