Condensation nightmare

Most double glazed windows are cheap crappy hollow PVC, with aluminium glazing bars (when you look into the glazing unit, can you see metal strips separating the two)?

Also the windows are sometimes poorly fitted into the brick/block frame, and cold bridging happens around the frame.

As for ventilation, set up your kitchen/bathroom extractors to stay on for longer periods after the lights are turned off.

More than that, it would help to know the age of the building, and the construction (brick & block, insulated or not cavity?).[/b]
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What is the type of construction - solid brick
Is the floor uninsulated? - loft is... other floors aren’t
Assuming it’s an old property, these could be key indicators; solid walls absorb external moisture & pass it internally; do you know if the floors have a DPM?

You seem to have adopted a structured approach to the problem & tried most combinations with only limited success so I would say your problem my well be caused by a high internal moisture content due to the property age/construction; you should also check for faulty guttering etc as this could be exacerbating a damp problem in the walls.

If the DG units are old, the sealed units may have failed creating huge cold spots where the moisture will condense.
We had this in our old rented place, It was rented so couldnt do a great deal to the building & the landlord didn't give 2 toots

however we bought a dehumidifier unit ( one of those clarke jobbys from machine mart ) & kept it running constantly it took a few weeks but it dried the place out nicely ( with a shocking amount of water discharged from it too )
you could try replacing 1 of the glass units with low e glass, argon filled with warm edged spacer for maximum performance. This should certainly make a big difference, albeit a bit costly if you can't do it yourself. I've changed a houseful recently that had the exact same problem you have had and it completely eliminated the condensation from the inside.

Great stuff..

Thanks for this
The next problem would be the condensation will go elsewhere, the moisture is still in the room unless you improve external ventilation. The more you insulated the house, the more condensation! In the old days, draughtly leadlight windows and open fireplaces was a good ventilation therefore no condensation problem then! In theory a dehumidifier can control the condensation up to a point but still returning warm moisture from the unit back into the room! A lot of condensation can be a lack of air movement therefore creating "trap condensation pocket" specailly behind the bed headboard and furnitures etc

So if there's not enough ventilation then the moisture can't get out. It can be difficult to get the balance right because too much ventilation can makes a house draughty!
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You should have vents in most rooms permanently open certainly in kitchen and bathroom.
well my kids use to be sick too often when the heating was off during nights, no way to turn it off. At least on low temperature running whole night long.
Quick fix.
You say you cannot leave windows open all the time so you need to install trickle vents in the upvc window heads, it is possible to do this retrospectively but you have to know what your doing. If you cannot do this, physically fit air bricks in all rooms. Ideally you will have to fit two, one just above floor level and one just below ceiling in each room.
The heating will have to be on at a low temperature 24hrs a day.

You also confirm it is a solid brick house and not cavity. This gives me an idea of its age and type. You will certainly be getting cold bridging from the outside to inside. This would not have been a problem when the house was built as the open fires, which I presume you had which are now blocked up, would have created there own ventilation by drawing in fresh air through the gaps in the original draughty windows
and up through the gaps in floor boards and skirtings and drawing it up the chimney taking any moisture out with it.
Talking of which, As I suspect you have suspended wooden ground floors, please check your air bricks are well clear of soil or undergrowth, because with such a damp property I would worry that bad air circulation below the floor will allow dry rot to establish.
Also with a solid walled property it is imperative not to have ivy, or shrubs against the wall as the house must breath.

Long term.
It would be great if you could fit 25mm kingspan or similar insulation board the inside of the outer walls and then plasterboard over it for decoration, and that would save on heating cost and increase room temperatures, but that is a major construction job, however you will still have to have air bricks or trickle vents.

And finally, in answer to your question, Will this pack the house too tight and increase humidity?
I can see why you ask that, and my answer is NO. Because, insulation in itself will not increase humidity as it does not produce moisture, you and your family do that. But it will reduce the amount of energy you need to heat the house and it will stay warmer longer and more importantly it will remove another cold surfaces where mould creating condensation settles . The extra insulation will allow you to increase air changes by controlled ventilation, ie air bricks, trickle vents, extract fans etc without feeling the cold or horrid drafts.
Good luck.

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