Moisture on ceiling spotlights

FreshlyCutFlowers

Apologies for the long detailed post. I've been dreading winter coming and really need some advice as its taking my sleep away. Local tradesmen havent been too helpful as I think its hard to see an immediate fix.

I have a victorian 1890s house with a rear ground floor extension. This extension stands directly on concrete and has a slanted tiled roof. In winter it is difficult to keep it heated and I let it go down to 11-12 degrees last winter at night and 15 in the day, that's when I spotted water droplets on my spotlights. The roof was inspected and deemed in great shape.

The ceiling is insulated with celotex boards, however around the spotlights they have cut holes in the celotex to fit the spotlights in. On my side by side the spotlights are marked as red circles, you can see how that causes the frost to melt there first.



In January 2022 I had a leak at the bottom of the ceiling, right in line with the cooker flue. The roofer said everything looked find but wind most likely blew some water in under the lead sheet around the cooker flue and traveled down the wooden beam to the bottom. He sealed down the lead sheet.

Fast forward to now
This year I wanted to see if I could reduce my general issues with the room it by keep the heating on all night, so I had the thermostat at 15.5 continuously. I also kept a dehumidifer on to keep it no higher than 55% humidity.

Still, on the spotlights that are lowest in the roof (highlighted in green on the image above) there was droplets on the lowest spotlights in the kitchen and just some light 'fog' on the lowest spotlights in the other rooms. The spotlights on the highest point in any room were all fine.



In my bathroom the spotlights are one whole piece so no air come through them betweenthe lamp itself and the outer ring. These lights do not have condensation on them.

I could buy new spotlights maybe and have them installed, but I worry that it'd just mask the problem of humidity forming in my void? It seems very relevant to me that its the bottom ceiling spotlights that tend to get the issue since its a tilted roof.

My previous owner had a gap around the boiler flue, as if to ventilate the void from inside, maybe?
I have tightly packed some insulation material to stop moisture / warm air from the cooker to go in. Maybe it's the issue?


What do anyone recommend I do as next steps?

grumbler

Well, it's obviously condensation caused by poorly insulated roof and cold spots made by downlights with metal bodies. Possibly, the condensation is facilitated by the moist air flowing up through the lights.

You can try replacing one downlinght  with a modern very slim one, adding insulation to the void and see if this stops the condensation.  Ultimately you can fill and seal the recess completely if you use a slim surface-mounted downlight.

FreshlyCutFlowers

grumbler said:

Well, it's obviously condensation caused by poorly insulated roof and cold spots made by downlights with metal bodies. Possibly, the condensation is facilitated by the moist air flowing up through the lights.

You can try replacing one downlinght  with a modern very slim one, adding insulation to the void and see if this stops the condensation.  Ultimately you can fill and seal the recess completely if you use a slim surface-mounted downlight.

I am so thankful for the reply. I feel very helpless with this issue as nobody has been able to tell me what the issue is.
Yes, the downlights have long metal bodies behind them. I am very interested in getting this done ASAP, do you think that is feasible or should I wait until next summer now?

It sounds like I need multiple people for this? I don't think I can open the roof and trust myself to put it back down correctly, so I'd need a roofer to come in and at least take the tiles off and add insulation. There is no access to the void from inside. I know some of the plasterboard is damaged around where the lights are inserted due to how strong the prongs are so they have 'dug into' the plasterboard. Is it maybe better to do the whole job from the inside and replace the plasterboard as well? I imagine when the lights get taken out next time the plasterboard around it will crumble, it's that damaged.

If I get a roofer, will my whole roof essentially need to be taken off and replace the celotex entirely or do they fill the open spots only instead of adding brand new celotex boards?

Can you please link me to an example modern very slim down light? Can I install them myself do you think? I have no electric competance.

edit: The previous owner was a roofer and they built this themselves. Why on earth would he have gone for the current solution? Is there a downside to using the slim lights?

Sorry for all the questions, but thank you again for taking time to leave a comment.

FreshlyCutFlowers

Is it possible that this isnt a big issue? Did the previous owner just live with it because the moisture appears on the lamps and doesnt collect in the void?

grumbler

What I suggested can be done at any season and doesn't require opening the roof. A job for a DIYer or an electrician. Try this with one light and if this works, proceed with the remaining.

  - a downlight similar to yours. It can be either GU10 mains voltage or MR16 12V with a transformer.

 

- an example  of slim downlight (mains voltage). It doesn't have a bulb. If it fails, the whole fitting needs replacing.

- an example of surface- mounted light. It doesn't need a round hole in the ceiling, and can be any diameter.

Generally, you can get rid of all recessed downlights and replace all or some  with big LED slim ceiling lights.

ThisIsWeird

Hi FCF.
I think Grumb has it covered, and has also provided a good solution.
In essence, tho', I don't think this is actually a 'problem' that will, in itself, cause harm. 
That formation of droplets is clearly condensation - ie it's from the moisture suspended in the air, and is finding the coldest surface to condense out on. It is not from a 'leak'.
I presume that if you turn on these lights, the cond soon disappears as they heat up? 
Of concern, tho', is why they are the coldest surfaces, and that seems to come down to design - the ceiling may be Celotexed, but the areas above these lights seem to certainly be not. Do the windows in that room also have cond on them?
I'm astonished at the defrosting on the roof, tho' - that seems extreme! Is the trickle of warmth presumably passing through the light really passing straight up to the tiles to cause this? I'm surprised it isn't just dispersing as soon as it gets in to the ceiling void - whatever type it is!
We can only assume that the roof has been built correctly - but surely, as it's the guy's profession. But certainly, the gap around the pipe is not intentional ventilation...
I'm with Grumb with a potential solution, but please don't expect it to transform the heating ability of that room - it won't. So I would choose sealed, LED surface-mounted light fittings with which to replace the current spots. Do you like these spotlights anyway - are they not too focussed?!
Anyhoo, assuming you do find a light you like, then the existing would need pulling down, and the wires to it disconnected. Then you look on FB Marketplace for offcuts of Celotex type insulation. You mark out the size of ceiling hole, and cut (presumably) cylinders to match. These get squished up into the ceiling to fill the hole and provide insulation - clearly the cable still needs to come through, so make a central hole for this. Then fit the surface mounted lights over it.

If you decide that these rooms are not worth heating over winter, that's fine, but DO make sure it's well ventilated instead - keep that damp at bay.

FFHillbilly

the lights you have currently are designed for halogen bulbs so they will have holes in the top, air can pass through the gap round the face of the bulb and go up through the fitting and escape, so this will make the room colder.
replacing them with any LED downlight will stop the air moving though and will help a little bit, but if theres little or no insulation in the ceiling then you are always going to be fighting a loosing battle trying to keep it warm.
edit: just re read the bit about the celotex and the holes above the downlights, filling these holes up with fibregalss insulation should help
replacing the downlights for ones with a plastic bezel will also move the condensation problem to somewhere else in the room

Eldi_Dos

As a interim measure until you can get the work done leave the shower room door open and leave fan on constant, hopefully this will reduce moisture levels in your extension.

FreshlyCutFlowers

grumbler said:

What I suggested can be done at any season and doesn't require opening the roof.

I appreciate your messages a lot, thank you.
I am crossing my fingers that I am missing something: How would I go about filling up the void with insulation like celotex? The only access I have is the tiny down light. The void between my ceiling and the tiles is very small, it is not a 'loft space' with room for a person and there is no access into it from inside.
I think I could manage to fit the LED downlight myself, something like this https://www.downlightsdirect.co.uk/aurora-slim-fit-shallow-led.html

But the missing insulation is square and bigger than the hole.

ThisIsWeird said:

Hi FCF.
I presume that if you turn on these lights, the cond soon disappears as they heat up? 
Of concern, tho', is why they are the coldest surfaces, and that seems to come down to design - the ceiling may be Celotexed, but the areas above these lights seem to certainly be not. Do the windows in that room also have cond on them?
I'm astonished at the defrosting on the roof, tho' - that seems extreme! Is the trickle of warmth presumably passing through the light really passing straight up to the tiles to cause this? I'm surprised it isn't just dispersing as soon as it gets in to the ceiling void - whatever type it is!
We can only assume that the roof has been built correctly - but surely, as it's the guy's profession. But certainly, the gap around the pipe is not intentional ventilation...
I'm with Grumb with a potential solution, but please don't expect it to transform the heating ability of that room - it won't. So I would choose sealed, LED surface-mounted light fittings with which to replace the current spots. Do you like these spotlights anyway - are they not too focussed?!
Anyhoo, assuming you do find a light you like, then the existing would need pulling down, and the wires to it disconnected. Then you look on FB Marketplace for offcuts of Celotex type insulation. You mark out the size of ceiling hole, and cut (presumably) cylinders to match. These get squished up into the ceiling to fill the hole and provide insulation - clearly the cable still needs to come through, so make a central hole for this. Then fit the surface mounted lights over it.

If you decide that these rooms are not worth heating over winter, that's fine, but DO make sure it's well ventilated instead - keep that damp at bay.

Thank you for a detailed response. Knowing that it (probably) doesnt in itself cause harm makes me feel a lot better.
Yes the droplets pass over time if I turn the light on. I guess we won't know for sure but my fear was that warm air must also be escaping up through these vents and maybe that water gets stuck in the void? No clue if that is a real concern but I have had some other issues in this area previously, see pics below.

The windows were free from condensation

It's a very shallow void. The celotex holes are square and bigger than the holes so getting new celotex in wouldnt be doable from within the house I think. I think I'd have to open it up somehow.
The lights: I dont have a lot of money spare so I hadnt intended to change anything unless its for a practical reason. This is a reason I am willing to change for.

I think I may have caused some damp the first year I lived here as I didnt realize how to do things so I kept windows shut a lot during the cold and I also hadnt covered the hole by the flue. I did however have an airbrick that was open so I thought that would be allowing air to trickle out.

Ventilation: What do you suggest? Most of these walls external so it gets proper cold if I don't heat, so I have to spend some on heating. Currently what I do is I ventilate well in the morning and afternoon but then close it up and put on the dehumidifier.


Here are some issues I have with the walls along this room. A lot of the corner between wall and ceiling has a crack in it from the first winter I was here.

I also had a person in to look at this wall but he said it was not to do with any of this and was likely just plaster contracting due me letting the room get too cold (10 degrees)


Hadnt included any of this as I was assured it wasnt a big issue, but maybe this is all damp? 

FreshlyCutFlowers

ThisIsWeird said:

 But certainly, the gap around the pipe is not intentional ventilation...

Could this be a part of the problem? Should I try to seal it 'properly' ? 
I saw something like this can be used but thought it was very expensive. I also don't know if it will really fit properly as the ceiling is 'angled' and this assumes it is flat.

I love my house except for this room and unfortunately I spend lots of time here in the cold.
I wish I could pay someone trusted to come help fix it up a bit but I don't really even know who would take a job like this. It being 'damp' seems to just be treated as magic and its hard to find someone who knows what to do.

FreeBear

Swapping out recessed light fittings for integrated units is not always straightforward - A small fixed LED downlight might need a 65mm hole whilst a fully adjustable GU10 fitting could be a 90mm hole. Making a hole bigger is a faff if you are doing it neatly. Making the hole smaller takes a lot more effort. So before you go out buying new fittings, pop one of the old ones out and measure the diameter of the hole.