Condensation and damp in house, why?

[Endwalker]

I recently had my cavity wall insulation renewed and ever since then I've noticed an increasing smell of damp in the house, particularly in the hallway and front room. In addition to this the windows are covered in condensation every day, I'm having to wipe down the frames and sills daily as they're wet, black mould is growing around them and also across the ceiling of the external wall in my bedroom. I wash it off with bleach water and a few days later its back.

This was never an issue until I had the cavity wall done, I've lived here over six years and never had damp or mould. The house is properly heated, I don't dry clothes indoors or on the radiators, the vents are open on the windows, I sleep with the window cracked because I like the fresh air, and I open the windows to air out the rooms while cleaning each day.

Does anyone have any suggestions about what could be causing this issue and how to get rid of it?

Sorry I don't know! We are in the same situation though (1930s semi) and so I am hoping that someone is able to offer practical advice.

I think you’ve answered your own question, haven’t you? It’s the cavity wall insulation.

When was your house built? Over-insulating buildings isn’t always a great idea, depending on their era and construction. Buildings need to breathe.

Its the CWI doing its job. My understanding is it will settle as the house gets used to the new level of insulation.

Personally I'd buy a dehumidifier to keep rhe mould at bay whilst it goes through the process.

Not all walls should have that cavity foam. Cant think which one but it might be north facing walls.

They could have overfilled it too so its breaching certain points. Get them back to deal with it properly.

Exactly the same problem, I don't know what to do. Black mould, damp walls all since CWI.

An MP is calling for an independent inquiry. This article is from early this year.

www.thisismoney.co.uk/money/news/article-10390579/Botched-cavity-wall-insulation-ruining-homes-causing-damp-mould.html

My old house couldn't have it done as the damp proof course wasnt high enough. Meaning damp would basically soak up through the cavity wall insulation. I think its because of the slanted drive?
We could get a layer of bricks put in but was too big a job

Been upstairs and the corner of my bedroom ceiling is weeping, definitely think it's the insulation.

Looks like I'll be making some calls tomorrow then.

Did they install a product that can absorb water or platinum bead that won't?

Condensation settles on the coldest parts - warm air holds more moisture than cold air, so when the temperature falls the moisture settles on the coldest window /ceiling / etc.
Because your walls are insulated their surface is staying warmer than it used to. So the condensation settles elsewhere. And because they’re insulated, damp air isn’t moving through the walls as much, so there’s less moisture equalisation.

The “solution” is to heat the house more, and ventilate it more. Which is probably the complete opposite of what you were trying to achieve with the insulation. Personally I’d also be running a dehumidifier and making sure extractor fans were working effectively in wet areas(bathroom, kitchen).

The cavity in older homes was to provide separation of the outer and inner walls of brickwork.
By filling the gap there is now no space for air circulation between the two brick walls. The insulation also provide a bridge between the outer wall to the inner wall for moisture penertration.
Insulation can also cause colder surfaces within the walls as the internal heat no longer passes to the outer wall causing condensation to form internally.
Check your gutters, and rainwater systems to see that they are not full of leaves, and do not leak.
Unfortunately some old buildings are better left as built rather than disturbing the equilibrium with modern materials and methods that are sometimes not suitable for their type of construction.

It's a 50s semi. Have been outside to put the bins out and had a look at the gutters to check for leaks, there don't seem to be any but I did notice that the airbricks are all filled with silicone so are in effect sealed shut

I don't know why I didn't notice this before but I haven't used the garden much lately so haven't looked all

that closely at the brickwork.

Heating is on a fair bit, at least twice a day at the minute and the house is usually around 20C according to the thermostat and the temperature readout. All of the window vents are open, I sleep with a window open, and I open the windows to air the rooms while I'm cleaning.

Airbricks should never be sealed shut. You need them clear to ventilate the sub-floor. Blocking them leads to rotten joists.

Previous posters are correct in that the correct way to get rid of condensation is greater heating and ventilation.