Moisture seeping up through wooden floor

My 2-bed apartment is 6 years old. We're on the ground floor (car park underneath). Over the past three winters I've noticed the main bedroom gets very damp but only in the cold winter months. Therefore, I thought it must be condensation. Initially I tried opening the window for longer periods during the day. (There is also a large vent in the wall and a trickle vent on the top of the window, both of which are open and working correctly).This didn't make any difference to the problem. When Summer came the problem went away as the temperatures rose.
Last Winter it snowed and the problem got much worse so I called in a builder and Quantity Surveyor to investigate. They cut a couple of holes around the window recess but said everything looked normal in there and aside from ripping the whole wall down it would be impossible to find the cause of the moisture. They said it was condensation but that it was the worst case of it they had ever seen! They recommended I get a de-humidifier and cross ventilate the apartment. I did both but it made absolutely no difference. By that stage the Summer was coming and the problem eased again.
This Winter it's back with a vengence. In the evenings when it starts to get cold, moisture starts to appear on the wooden floor in the corner of the room next to the external wall, along the skirting and floor under the window and in the wardrobe (all along the same wall). After a few hours droplets can be seen on the floor and skirting boards and the wall is wet to the touch and there is a small pol of water in the corner of the wardrobe. (The skirting is swollen in parts, as a result of the moisture.)

At this stage I am sick of this and just want to get it sorted out once and for all as my new born baby has to sleep in that room with us and the dampness is affecting his health. (My 2 yr old is in the other room so we can't move in there). It's depressing. Our matress is mouldy, the wooden bed frame, lockers and blinds are mouldy not to mention the clothes and shoes I've had to throw out after finding them covered in mould and stinking in the wardrobe. At this stage I don't even use the half of the wardrobe next to the wall.
Please don't reply telling me that this is condensation and I need to ventilate/heat the room, get a de-humidifier or stop drying clothes indoors. I've tried all of it. I open windows in the apartment EVERY DAY to combat condensation, I use an extractor fan every time I cook, there is also an extractor fan in the bathroom which is always used, I have a condenser tumble dryer and don't air dry any clothes.
I don't want to treat the symptoms. I want to find the cause and fix that once and for all.
If anyone can recommend someone who can actually fix this I would be EXTREMELY grateful as would my new baby.
Thanks

If you look outside, over the window - are there any sort of small overflow pipes coming out of the exterior wall (at the level of your bedroom ceiling/floor of the apartment over you)? If there is have you ever noticed excessive water pouring out of them, & if so does it land or splash on your windowsill?

Thanks for the reply. I checked and no, there's nothing. Everything looks fine from the outside. The only moisture on the windowsill is from the little holes to let condensation moisture flow out.

Oh, ok - I thought it might have been similar to a problem I had a few years ago which was caused by a leak from upstairs & the overflow was gushing onto my windowsill which seeped in through the bedroom wall & behind fitted wardrobes.

Back to the drawing board!

Hi Strewth,

I'm very sorry to hear you have such a severe problem.
The last thing you need is a talking shop, but you have asked here for advice.
This issue of condensation can be tricky to deal with in real life, although several principles are well understood at this time.

The first thing is to understand whether it is condensation, a leak, or a combination of the two.
Condensation is caused by the interaction of warm moist air, relatively cold surfaces, lack of insulation and lack of ventilation. The moist air is coming from somewhere.
Water ingress is caused by a leak, the end destination of which is within an occupancy. The water is coming from somewhere and not getting away outside the building.
These are two distinct principles but one can affect the other.

If water gets into any built construction [whether its from a high level leak, inadequate weathering details, internal pipework, damage no repaired or poor maintenance] it will find its way to the lowest level sometimes through pinhole penetrations and strange routes through construction joints that are not immediately visible to the naked eye OR via opening up.

The location where this leak water gathers becomes saturated. Even properly installed insulation can take up water, or become surrounded by water [if its closed cell insulation] to such a degree that its insulation properties are at best temporarily reduced to a degree that allows condensation to form in an on adjoining constuction.

This suggests that complete demolition could be needed to physically trace the fault, but normally this is not carried out. A good building manager gets to know his building well and can identify problems and their sources. A detailed review of the construction drawings may yield little of value because it could be something fallen into the cavity that is allow moisture to bridge the gap and run down the external face of the inner wall [if its a cavity wall, that is]. So you start with where the problem is manifesting itself and work backwards.

The location of the problem may provide clues to the possible cause(s).
Its at the bottom of an apartment at the bottom of a building.

Warm air rises and absorbs moisture in the form of water vapour which is invisible.
Normally it rises until it hits a cold surface, and deposits its water vapour as visible moisture.
This often results in damp patches on ceilings and around window reveals in poorly ventilated areas with relatively cold surfaces.
The issue of relative coldness is as important as dewpoint, the temperature at which vapour precipitates from the air as moisture, but the thing here is that the dampness is occurring at low level, not high level. Very low level, which is unusual in my experience.

Normally, moisture and damp at low level suggests rising damp via capillary action via a damaged damp proof course or damp proof membrane in the floor, but you say you have a car park beneath you.

If your floor is entirely above the car park with air beneath it and has no insulation it may act as a massive cold bridge all along its surface.
Even if your floor is insulated on the flat face of the supporting slab between the downstand beams the downstand edge beam may be uninsulated causing a huge cold bridge along the outer wall at floor level.
These problems will all be exacerbated if your apartment is single aspect located on the north face of the building, because lack of direct sunlight will reduce the rate at which the out wall dries out.

The fact that this is seasonal, suggests that both insulation and weather play a part and so all of the options discussed in outline form above may be constributing to the problem.

I think that states the possible sources of the problem.
Back to the good building manager and getting to know the building.

My two cents worth of advice, which this remote cannot be termed competent, merely speculative.

1. Ask around and see if other apartments have this problem.
Poor building generally resulting in missing insulation in places will cause problems all over the development - don't be shy - ask.
2. The problem may arise from lack of local insulation as noted above, and exacerbated by lack of insulation in the external walls [although I'm still betting on that exeternal uninsulated beam].
3. The problem may not be local, it may be caused by a services leak within the building. Something as small as pinprick penetration in a central hearting pipe or weeping joint, a perforated underfloor heating pipe, or an unsealed shower tray yielding only a drip every few seconds when the shower is used can cause the problem if it falls into unventilated interstitial voids and migrates down to your level.
4. The problem may be at high level and caused by an unsealed parapet or flat roof allowing downward migration of water to your level. Such leaks will pass by and not cause problems for the upper occupancies but only cause problems where it lodges. In one period house I investigsted, a leak in a chimney was manifesting itself at a point on a chimneybreast where the water had travelled down internal brick joints until it found a bed joint it couldn't penetrate. Took weeks trying to locate it. Solve by simply raking out and repointing the entire chimney, recapping it and installed new flashing. With all the possible sources sealed, the structure dried out through normaly use and the problem was solved.
5. Suspended apartments over car parks may not have proper detailing at the base of their cavity wall. If it is built directly off the full slab depth of if there is a shoe on the slab that projects out to support the wall, there should also be a detail protecting the supporting face from absorbing water running down the inside face of the outer leaf and saturation the slab. Lazy detailing here coupled with a total lack of insulation of the slab proper creates a water saturated cold bridge.
6. A snot of mortat [yes, its a technical term] on a wall tie could be allowing bridging of the cavity with water running down the outer face of the inner leaf to a bed joint or the slab where it gets in to your apartment.

I hope I have given you an idea of the complexity of the issues involved based on my own experience of such situations and outlined some hard questions for you to ask anyone in charge of the building/ your neighbours/ any future professionals you engage.

If you want more detailed advice I'd need to see the property and if you want to explore that option, PM me.

ONQ.

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