ᐅ Does Insulation Eliminate Mold or Not?

When we upgraded the windows in our house (also triple-glazed), we were warned that there could be issues with mold. So far (a few years) we haven’t noticed any problems – what I have learned is that mold problems are more likely if the insulation in the house is uneven.

ypg schrieb:

In an existing house, you would probably retrofit with a decentralized system.

That depends on the house. True old buildings often have unused chimneys (since not every room needs a stove anymore). These can be used for the central ventilation system. Together with high ceilings, which can be lowered, this can work well.
We are currently having this planned for our house, and the planner has already given their preliminary approval...

SoL schrieb:

Genuine old buildings

… are unfortunately quite rare. The typical “old building” from 1950-1980 does not qualify.
I would also prefer central over decentralized.

Hello everyone,

First of all, I wish you all a happy new year! Lots of health, success, and above all, no problems with your property :-)

Thank you very much for all your previous answers – they have been really informative and helpful.

Today we looked behind the cupboards that are placed against an exterior wall. It was a disaster!

There was so much mold behind the cupboards – I have never seen that much before!

I have read that cupboards shouldn’t be placed too close to exterior walls to allow air circulation.

Today, we sprayed all the affected spots on the walls with mold remover, opened all the windows, and left the house for three hours.

It is so bad that I actually don’t want to live here anymore. But my husband says that adding insulation will improve everything.

I am really more desperate than ever before!

I measured the temperatures on the exterior walls with a laser thermometer: they drop to 11–16°C (52–61°F) in the corners, and in the center of the walls they are about 16–20°C (61–68°F). Interior walls and the ceiling are mostly around 22°C (72°F).

We have a device that measures humidity and room temperature. Usually, the temperature in the bedroom, kitchen, etc. is about 21°C (70°F), and the humidity is between 60 and 75%.
I know that more ventilation would help, but should I ventilate every hour now? Then the house will never get warm, and we will heat unnecessarily.

It feels like a vicious circle: either cold and no mold, or warmth and mold.

As I said, I am really desperate, and the mold we found today makes it even worse.

I don’t even want to check behind the kitchen cupboards (whether base or wall units). It probably looks the same as behind the wardrobes.

My husband says that we will insulate the house from the outside this summer and then see if the mold comes back. If it does, we would need a ventilation strategy – most likely with decentralized ventilation systems.
I have already watched some videos about this on YouTube. If the mold doesn’t return, we would avoid installing ventilation systems for now, since they are not particularly cheap.

My question: Do decentralized ventilators need to be installed in every room, or are they enough just in the kitchen and bathroom?
Does anyone have experience with this? Can someone recommend good and reasonably priced ventilators? What types make sense?

Sorry for the long text, but I had to get all of this off my chest and I hope for helpful advice and a solution.

I wish you all a great weekend!

Kind regards
Julia

julia123 schrieb:

There was so much mold behind the cabinets – I’ve never seen that much before!

julia123 schrieb:

I read that cabinets shouldn’t be placed too close to exterior walls so air can circulate.

Exactly. The wall is cold (like the outside corners), and if the cabinet is directly against it, no air can reach it.

julia123 schrieb:

But my husband says that insulation will fix everything.

Men are always right, aren’t they? In this case, actually yes, because then the exterior wall is warm from the inside and water can no longer condense.

julia123 schrieb:

I measured the temperatures on the exterior walls with a laser thermometer: in the corners they drop to 11–16 °C (52–61°F), and in the middle of the walls they are around 16–20 °C (61–68°F). Interior walls and the ceiling mostly measure 22 °C (72°F).

julia123 schrieb:

Humidity is at 60–75%.

At 21 °C (70°F) and 60% humidity, the dew point is just under 13 °C (55°F). So the corner behaves like the soda you take out of the fridge in high summer. At 75% humidity, the dew point is even 16.5 °C (62°F). Unfortunately, physics always wins here.

julia123 schrieb:

My husband says we will insulate the house from the outside this summer and then wait to see if the mold returns. If it does, we would need a ventilation plan – probably with decentralized ventilation units.

Yes, then there is a very high probability that no more mold will develop because the walls will be around 19–20 °C (66–68°F).
BUT: You should develop a ventilation plan already today. Also consider decentralized fans now. These should be installed before insulation because they require core drilling through the exterior wall. If you don’t want electrical cables inside the walls, the fans can also be powered via cable and socket.
At least make sure you have basic ventilation.
Many manufacturers also plan for this.

julia123 schrieb:

as they are not exactly cheap either.

For €400 (around $450) each plus installation (which you can do yourself), you can get good devices. Money well spent.

julia123 schrieb:

My question: do decentralized fans need to be installed in every room, or are they enough in the kitchen and bathroom?
Does anyone have experience with this? Can anyone recommend good and affordable fans? What types make sense?

Good question. Ideally, the air exchange required by your ventilation plan is achieved. I find the bedroom more important than the kitchen, for example – that’s where you produce the most moisture overnight in the whole house.
Please share your floor plan.
And yes, I have experience with central ventilation (in a new build) and decentralized ventilation (currently in a renovated older building). Please only use fans with heat recovery. They are a) controllable together (wired), b) have a night mode (lowest performance when it’s dark due to noise) and c) humidity sensors (especially useful in bathrooms). The cheap devices are pendulum fans – for example, 70 seconds air out, then reverse. There are more expensive units with a crossflow heat exchanger that blow air in and out continuously and are therefore quieter.
In my case, the units run almost continuously on basic ventilation. During the day, you don’t hear them at all, and at night in bed only very quietly (but not disturbing).
Feel free to ask any questions.

...and please make sure to ventilate properly and thoroughly. A temperature of 21°C (70°F) with 60-75% relative humidity indicates incorrect ventilation.

Be prepared to take several weeks or even months to reach acceptable levels, as (simply put) all materials have absorbed moisture that needs to be aired out first...