Apartment Ceiling Insulation and Ventilation

Hi In nite mare situation. My apartment ceiling in the living area developed a wet patch. Circa 50% of the area above is exposed to a terrace above. The ceiling above me, is Plaster board (backed with Foil), marginal amount of insulation and a Pre-cast slab. The slab is not externally insulated. The OMC looked into it and re surfaced the terrace with a sealer, but the damp patch kept reappearing. The agent for the OMC opening where the patch it was saturated. There was a lot of droplets hanging from the slab and would appear to be condensation. The OMC have asked me to monitor ….during rain and cold temperatures to see whether its condensation i.e Cold Bridging.

Basically on the run up to Christmas left it up to me to investigate. In the past when Cold briging issues surfaced in my apartment and other apartments (Minor stains) on the ceilings, they advised people to intall something like a demand fan or one of these Positive Input Ventilation Fan. I have a feeling the agent of the OMC is going to advise this.

Im considering funding the remedial works within my apartment if that is what it will take to get sorted. I have contacted companies that could do the insulation internally but they have advised getting in a ventilation company first to come up with a plan... Is anyone aware of a companies that specialise in this type of work ?

(The assumption here is that the wet patch in the ceiling is caused by heavy building sweating i.e. cold bridging)

I would advise against you undertaking any remedial works until you are reasonably sure of the cause of the dampness. You also need to bear in mind that you could be interfering with the common areas/space owned by the OMC and thereafter any problems could be blamed on you and become your personal responsibility.

Has a competent engineer assessed the situation on behalf of the OMC? Given that they have already tried to fix the problem and have been unsuccessful, I think this would be the minimum expected of them.

When was the apartment built? The government are due to introduce a redress scheme to fix serious issues in apartments built from 1991 - 2013. If your development falls within these dates it would be wise for the OMC to bear this in mind in how they deal with the issue?

No , no competent engineer has been called yet. It is the next move I have suggested to them before Christmas. The apartment was built in 2007, apparently building regs at the time didnt dictate that the pre cast slab be insulated on the outside (Which now they have to so that the Dew point is outside the building ). Im also open to making a conribution to do this as clearly this is directly impacting my home.....and impacting my mental health.
I do agree with you , that before any remedial works are done we would have to be more than reasonably confident that cold bridging is the root cause.
Clearly any remedial works that would need to be done, would (1) Be approved by the OMC (2) the work would have be done and certfied to current building regs

You likely already know this but the main cause of your wet patch would appear to be the exposed cold precast slab onto which your plasterboard ceiling is attached. When it gets cold the internal surface temperature of the slab is well below the dew point temperature of the internal air and therefore condensation is occurring (droplets) and causing the damp patch.
There is nothing you can do about the precast slab surface temperature I would think.
I would tackle this on 2 fronts:
1. Reduce the available moisture internally by reducing the moisture load (such as not drying laundry indoors), keep the place warm and crucially removing as much moisture as possible by improving the ventilation possibly by introducing a continuously running humidity controlled centralised mechanical extraction system or if that's not possible, a good dehumidifier may be appropriate. These items you can do yourself with little OMC involvement
2. Remove the internal ceiling and fit breathable insulation such as Calsitherm boards directly onto the slab and finish internally with breathable pb/skim. This would be a job for the OMC I would imagine

While not eliminating source of the problem (i.e. the thermally unbroken precast slab), this should go a long way in reducing the effects

HonestP said:

The ceiling above me, is Plaster board (backed with Foil), marginal amount of insulation and a Pre-cast slab.

Click to expand...

In theory the foil backing should be acting a vapour control layer above the plasterboard, preventing moisture getting out of the room below and into that cold space. I don’t think they’re too well regarded as the joints don’t tend to be sealed from above, but they should still be blocking a fair bit if moisture.

Are there other sources of moisture in the ceiling space by any chance? For example in my apartment years ago I discovered the bathroom extractor fan was not connected to the extraction duct, it was just venting the steam into the ceiling. Any chance you have similar in a bathroom or cooler extractor? Or unsealed downlighters cut into the ceiling perhaps?

Zenith63 said:

In theory the foil backing should be acting a vapour control layer above the plasterboard, preventing moisture getting out of the room below and into that cold space. I don’t think they’re too well regarded as the joints don’t tend to be sealed from above, but they should still be blocking a fair bit if moisture.

Are there other sources of moisture in the ceiling space by any chance? For example in my apartment years ago I discovered the bathroom extractor fan was not connected to the extraction duct, it was just venting the steam into the ceiling. Any chance you have similar in a bathroom or cooler extractor? Or unsealed downlighters cut into the ceiling perhaps?

Click to expand...

Yes the light spots on the sealings are very well sealed. The amount of moisture that could get up from the living area wouid be minimal in my view.
How wouid I go about getting the ducting checked to see that they are not blocked or connected incorrectly ?

HonestP said:

Yes the light spots on the sealings are very well sealed. The amount of moisture that could get up from the living area wouid be minimal in my view.
How wouid I go about getting the ducting checked to see that they are not blocked or connected incorrectly ?

Click to expand...

You would be surprised. The vapour partial pressure difference across the barrier can be significant and literally act to pump vapour through any hairline crack or pinhole. Don't discount it.

I feel your pain OP and it's so difficult to remedy due to not owning the void above the ceiling and related fire safety concerns

I have a similar problem in my top floor apartment. Foil backed plasterboard with no insulation. I am told the slab is insulated concrete slab for all the use that is to retaining heat in my internal space.

My second bedroom ceiling is destroyed with mould and staining. The apartment is difficult to heat on a cold or windy day.

Today, the heating on all day and the internal temperature just went above 18⁰ C at 8pm, now its 18.7⁰C, for a combi boiler temp of 60⁰C

Heat just seeps into the void below the concrete slab.

I assume the building regs on place at time of construction in 2004/5 would specify insulation in roof, which in an apartment would be above the ceiling.