Ceiling dampness: detecting source

[Gram]

Hello, We have a pitched area of ceiling that’s damp, especially late night/early morning. The problem has been ongoing for some time and originally we thought it was due to condensation, which is an issue throughout the house, but the bubbling of the paint has worsened recently and we're now thinking this may be a leak. The ceiling is dampest at the lowest point but the bubbling now extends throughout the section. (Pic 1). We are trying to determine the source of the dampness and considering the likelihood of three scenarios:

Roof/rainwater leak: The ceiling moisture appears to be originating at the same location at which there is a pitch change in the roof. (Pic 2). A roofer has advised that this is a very common place for leaks to begin. Though there are no broken tiles, rainwater may be finding its way through the tiles at this location (there is no cavity in this part of the roof). The roofer has given a quote to install sarking and wool insulation in this part of the roof.

Pipe leak: I have since been in the roof and found a copper pipe that runs through through the roof and curves downward at the spot where the pitched ceiling starts (I can’t see further as there is no roof cavity beyond this point). I got up on the roof and lifted some tiles at this spot, found the downward elbow bend in the pipe and noticed a circular hole approx 5mm in diameter. (Pics 3, 4). The damp ceiling is in a mud room, next to the laundry, so the pipe is likely running to the laundry. It may be that water is leaking out of this pipe and running down the pitched ceiling, however, the ceiling is damp on cold nights/mornings even when the laundry has not been used.

Condensation: There is quite a bit of condensation build-up on windows throughout the house, especially on cold nights. We’ve had 3 roof whirly-birds and 2 wall vents installed to address this but the windows still collect a lot of moisture. The sliding doors to the mud room collect a lot of moisture too, and given that the dampness is most apparent on cold nights / early mornings, it seems that condensation may be at least a contributing factor to the paint bubbling on the ceiling. Not sure though, if it would be enough to cause as much damage as we are starting to see.

We're wondering if anyone has any thoughts on which of these (if not all) would be the most likely scenario and what the best approach to solving this before the damage worsens could be. Thanks

 

[Paul Cumbria]

I am no expert in these matters but I will throw in my twopennorth if I may :

I note that there is no roofing membrane under the tiles, which is not unusual for older houses, and should not matter too much if the tiles are in good condition. Expensive and time consuming to fit unless you are re-roofing anyway, which isn't necessary if the roof is still sound with no broken or slipping tiles.
If the roof was leaking you would see damp and/or staining on all the timbers and brickwork beneath, which I don't see in the photos, so probably not a leaky roof then.

Are you sure that the pipe you see there is copper and not galvanised electrical conduit? It is difficult to see from the photo, but it looks more like the latter to me, especially given that there is a hole drilled in it. If it was a leaky pipe then it would be leaking permanently, not just when there is demand downstream, and again there would be evidence in the form of wetness and staining on the surrounding timbers and brickwork. You can most likely discount this option.

The most likely explanation is indeed condensation, as it appears at the same time as seen in other parts of the house. It will run down the sloping ceiling, so is damper there. Can you see water on the surface during colder periods? That would back up this theory.
There does not appear to be any insulation above this part of the ceiling, so maybe a cold patch there?
You have made some commendable efforts to improve ventilation, so maybe leave it for a while to see if this helps dry the house out, if not you will have to turn detective in order to find the source(s) of moisture. The more people and pets there are in the house, the more moisture is exhaled and sweated out, cavity walls may be bridged or have compromised insulation, there may be rainwater ingress from elsewhere (around doors and windows is typical) - just a few things to consider. It might be worth leaving the heating on 24/7, reducing the thermostat to say 15C overnight; I know energy is expensive, but if the fabric of the house suffers through damp any repairs required will be even more costly as well as disruptive.

Just a few ideas, I would be interested to know the outcome, so best of luck!

 

[Paul Cumbria]

I forgot to add - I have made the basic assumption that you have adequate ventilation (i.e. fans) in all bathrooms, kitchen, laundry room etc.
It might be worth fitting extra ventilation in the worst affected rooms controlled by humidistats which will start the fans automatically when the humidity reaches a preset level with out you having to remember to switch them on manually.

 

[Gram]

Thanks for this advice, Paul. This is the side of the house where there are generally more people and pets. Also, the whirlybirds installed in other areas where there is a roof cavity do not benefit this part of the house, where this roof (above which there is no roof space) is next to an extension (with a completely separate, tin roof). So, it does seem likely that condensation (which is obvious on the sliding doors and windows), is also collecting on this high, sloping ceiling. There is very little space between this ceiling and the roof tiles and no insulation between, so any humid air rising here would come into contact with a cold ceiling (and it is currently winter here). Do you think increased ventilation (leaving a door or window ajar overnight for example) might help, as opposed to leaving heating on, or will the heating reduce humidity? I don't know enough about this issue but I have read of 3 ways to tackle condensation: reducing humidity, adding insulation, and improving ventilation. Perhaps installing a vent in this room would make a difference (and be a cheaper option than installing insulation in the roof). I'm afraid I also don't know enough about plumbing or electrical circuits to identify the pipe in this part of the roof but the fact that it is directly above the spot where moisture is appearing made me think there could be a leak.

 

[Gram]

I will look into humidistats, which I'm not familiar with. We've had new extractor fans installed in the bathroom and laundry, and a new range hood in the kitchen to combat condensation. This room is a 'mud room' between the laundry, kitchen and hallway. It doesn't benefit from the ventilation in those rooms so this may be why humidity is collecting here. Is it possible icicles are forming on the inside of the roof tiles and dripping back down onto the ceiling from inside? I know this can happen in attic spaces. In any case, it would be good to rule out the possibility of a leak, which might be a more urgent problem. We can then experiment with different strategies to tackle the condensation.

 

[Paul Cumbria]

It does sound like you are doing the right thing with adding fans etc, maybe one in the mud room would make a difference, as this will most likely be exposed to moisture long term from damp clothing/boots and such like.
From the photos, although it is difficult to see closely, there does not appear to be any staining or mould evident which would indicate leaks or water ingress by other means.
As a general rule, the warmer and better ventilated the room, the less the likelihood of condensation, so yes, extra insulation is worth the cost and hassle. You will probably find that with more ventilation, the house will feel cooler so more insulation and heating would help here.
I mentioned the possibility of the electrical conduit because it does not look like copper pipe in the photos. It is difficult to offer specific advice as I don't know the regulations or building methodology where you are located. It would help you determine its use if you could see where it runs from and to - is there an electrical outlet or a tap/appliance below where the pipe bends downwards? A magnet will tell you if it is ferrous or other material, if ferrous it is unlikely (though not unknown) to be a water pipe; it is unusual though that the elbow with the hole in it looks like brass? There is some kind of electrical fitting on the affected ceiling - any idea what this is?