Help! Strange damp stains appearing all over my ceiling!

[MrOllieB]

Hi. I am new on here and hoped I might be able to get some advice.

Over the past 2 days lots of worrying damp stains have appeared on my ceiling. It has not rained but has been very cold (heavy frosts). I have lived in the house for a year and had some very heavy rain fall during that time (including the never ending rain storms that flooded lots of the UK last winter). There has never been any damp patches caused by rain.

This is the first time I have been here during a time of heavy frost so I am thinking (and hoping) it is that that is causing the problem, I just dont know why

I have attached some pictures and would welcome anyones thoughts.

The room has high ceilings and beams and there are timer struts (painted white) running horizontally across the ceiling. Above many of these struts damp patches have appeared. They have only appeared on the north facing side of the roof/ceiling not the other.
The roof outside is in good condition with no obvious signs of tile damage
Would anyone know why they would appear above these struts? The struts are solid wood (I guess they hold the roof panels/insulation in place but am not exactly sure of their purpose).

etc.
The house was converted a year or two ago (not by me) so the insulation/roofing etc should have passed all current rules/regs (I hope).

Please have a look at the photos and let me know your thoughts.

Cheers Ollie

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• 29 Dec 2014
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• MrOllieB
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[JohnD]

is the room humid? for example from cooking or wet washing?

Are the windows misty?

As it is frosty and you say it has not been raining I think there is a considerable chance that water vapour has been condensing on the cold parts of the roof and the water running down to your ceiling. It would be worse on the colder side of the roof. Water vapour is lighter than air (hence clouds) so it will naturally rise until it either escapes through ventilation, or finds a cold surface to condense on.

You can't trust the developers to have done a proper job. Try to download the plans from your local council website, free (at worst you might have to pay for a paper copy) and look at the roof detailing they were supposed to do.

I think you are going to have to cut out a square of the plasterboard (it is fairly easy to refix, fill and redecorate) in an inconspicuous place to have a look.

 

[MrOllieB]

Hi John

Thanks for your quick reply.

I dont think the room is humid. It is very well heated with modern electric radiators and a very new wood burning stove. All of which we have had on. Its pretty toasty in here at the moment and feels very dry. There is no mist in the windows, they are dry as a bone.

There is no signs of condensation on the ceiling. I was wondering if the tiles might get frost on their underside and then the heat of the house causes them to defrost and leak through?

Another thing that I just thought of is that we were away for 4 days and turned the heating off. When we got back it had been very frosty and the house was freezing. We then turned all the heating/fire on. Could this have been a reason do you think?

Thanks again. Ollie

 

[catlad]

Its condensation I don't see any vents and if they have used rockwool instead of kingspan then it will be even worse, the more heat you pump into the house the worse it will get.

 

[MrOllieB]

Hi Catlad

Thanks for your advice.

So would the condensation be on the other side of the plasterboard? Theres no sign of condensation or wetness on the inside.

Whats the best way of stopping it from happening?

If it only happens when its really cold is there anyway of avoiding it?

Thanks

Ollie

 

[catlad]

You need to build a ceiling thats one of the reasons why they were invented.

 

[JohnD]

it is possible to insulate your vaulted roof, using a vapour barrier and (preferably) a rigid foam such as Kingspan or Celotex. To do that you would have to pull down the exiting plasterboard, or possibly build another layer on the inside. The original plan should have taken that into account, hence my suggestion that you look up the original plans, then cut an inspection hatch in the plasterboard to see if it was built correctly. Ordinary plasterboard and mineral wool allow water vapour to pass through them, and which would lead to condensation on the cold side, which can then soak back through the wool and plasterboard.

If the roof has felt rather than a breathable membrane it will prevent water vapour escaping though the gaps between tiles.

Does anyone drape wet washing around your home, and is there a shower or bathroom nearby?

you might make some improvement by ventilating more, near the apex, but this will lose warm air as well as moisture. With such a high room I expect it is cool at ground level. Also look for any source of moisture such as a damp floor or plumbing leak, which will make things worse.

 

[MrOllieB]

Thanks John.

We do hang washing in the room to dry (but have not for a few days). There is a bathroom also but again it has not been used much as we have been away for a few days.

Thats all really helpful. I will look into it and hopefully resolve the problem.

Cheers

Ollie

 

[JohnD]

Draping wet washing is the biggest cause of condensation, damp and mould in UK homes. You might as well throw buckets of water on the walls.

The bathroom must have a powerful extractor or the steam will diffuse around your home and rise to the ceiling.

 

[Mw Roofline]

Sorry for hijack but what are those tiles called? Thanks

 

[cotswoldbuilders]

Sorry for hijack but what are those tiles called? Thanks

At a guess, Redland Delta ?

 

[catlad]

I have not seen that tile before but its not a redland delta.

 

[Guitar_man]

You often find that heavy sideways rain will penetrate tiles. If there is no felt then it will stain the ceiling. You might find it then drys naturally and never recurs( I have seen this before).
It could be worse you could have monofol membrane instead of felt lol (see my thread).