Is 19 - 23% a high moisture reading for a ceiling?

[MurkyMo]

I live in a semi detached bungalow that feels very damp following rain. It's housing association so have been on to them several times about it over the last 2 years and they've come out and stuck a meter on the walls and said the readings are normal. But the humidity in the house after rain goes up and up and at it's worst it was 80% at 18 C.

So I bought a moisture meter myself and investigated and found in all rooms that there are spots on the ceilings beside the external walls that show high readings following a lot of rain. The worst was 23.8% in one room.

So is this considered high and can I now push hard for it to be investigated further?

Yes, it’s wet. Do u have mold? Can u get into the loft to check for leaks.

Yes there was mould in the dampest spot where it read over 23% but I bleached it away and the painter put some sealant over it so it hasn't come back. But having stuck in the prongs of the damp meter many times I can see there is black under the paint. There is another patch of mould that seems to be growing from the other side of the ceiling rather than on the inside. It's a cold spot as there used to be an outside light there that was removed and just a piece of wood screwed on to cover the hole.

I can't get into the loft unfortunately so will have to wait for the housing people to do something. But important that I can tell them there is definitely a problem as they keep telling me there is no damp problem here. They actually told me to turn up the heating thermostat. One even suggested I leave the heating on around the clock. 😱

What should the acceptable level of moisture be in a bungalow ceiling ?

Those moisture meters arent very accurate which is probably why noone wants to stick their head above the parapet and say how dry a ceiling should be. I would judge it by the presence of damp patches and mould.
I think you are saying that there are visible damp patches? It is near the outside of the room or the whole ceiling? Is it worse after rain? Is it worse when the weather is colder?

No visible damp patches but there is the 2 mould patches in the bathroom. I ventilate the house like a German (!) so no mould growth elsewhere apart from at the window seals but I clean that regularly. However is it definitely worse after rain, the whole house feels damp with some rooms worse than others. The damp areas are all at the edge of the ceiling where it meets the exterior walls. After prolonged rain the damp spreads inwards across the ceiling and after a long dry spell this retreats.

Had a long cold dry spell here for the last few weeks and the house was great, no dampness at all, RH below 50% at around 19 - 20 C

Even with the unreliable nature of these damp meters, isn't 38% bad anyway. And with it getting worse after rain and better after dry periods doesn't that strongly indicate water ingress from somewhere?

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Yes that 23% is getting into high
80% humidity is very high

Putting sealant over the problem makes it look like it’s sorted but is solving nothing
The root cause needs to be found and solved. Once done ideally any finishes need to be removed, walls dried out ( dehumidifier will quicken this up ) and then decorate with new breathable finishes.

Well the 80% was probably due to it being Autumn and still quite warm outside with 95% so opening windows did not help bring down the RH inside. Autumn has been the worst for a damp bed and clothes in the wardrobe due to this.

Will put in a repair request and see how that goes but unfortunately the contractors they use are not the best. Everything is the cheapest of the cheap with them.

Could it be some issue with where the roof meets the walls ?

Normally there is a gap between the roof and the walls to allow air to circulate in the loft, ironically to prevent build up of humidity. In a new house they normally have planks with ventilation holes in (don't know the correct term).

Maybe some water is getting in through those gaps. I don't know what could cause it, maybe they haven't felted right the way down to the edge of the roof, maybe the gutters are overflowing and the water is somehow getting in.

Have you gone up into the loft to inspect it ?

Someone probably will be a long

Even with the windows open a humidity of 80% is very high

Anything above 60% and you’re getting into mould build up etc and potential health issues for occupants

Yes I think some problem with the roof above. It had actually been a grow house before I moved in! Maybe the "gardeners" or the police did something up there to cause damage and let in the rain. I wish I could get up there to look but my step ladder isn't big enough.

I know. That's why I'm forever airing the place when it's bad. At least once a day opening everything for 5 or 10 minutes. I'm convinced that's keeping the mould at bay. And the fact that it all dries out if it doesn't rain for a few weeks.

Maybe they rigged some sort of rainwater collection system to catch the roof rainwater to feed the grow. After all, getting water, heat and light to the grow are the major issues in cultivation.

And maybe that system is now broken or overflowing.

With those readings, it does sound like you may have an active leak @MurkyMo

It's essential that you are persistent with the housing association, as you know, damp and mould spores are not conducive to good health/sound structures.

I would try getting the gutter cleared and checking the loft space for leaks and insulation as a first plan. Gutter maintainence is your job as a Tennant. Insulation and checking for roof leaks isn't but it might well be a lot quicker to get a handy person to pop up and see what the situation is and take some pics so that you have something to send to the council.

I'd second the gutter possibility. If they overflow, they often leak straight onto ceilings. When did you last clear out your gutters?

Around 4 months ago