The mold dog detected mold gas in the garage and up into the house.

[The_Curious_Builder]

Oh well. It happened. I have a garage on a slightly sunken hill with an upper structure (like a laundry room) that is connected to the main house. Tiles on 120 joists above the garage. The mold dog reacts to the gas itself and what the mold spores release. The dog marked in the room above the garage (tile floor on 120) which in turn has a door into the rest of the house. Despite this being my expertise, I am struck by how foolish one can sometimes be as a homeowner. Stingy with heat for example...
So now to the confession.
Number one: Yes, you always need to have heat on in all spaces that are insulated. This is to lower relative humidity but also to achieve a thermodynamic drive.
Number two: you need either full-scale ventilation or in combination with a dehumidifier. Will install VL-50 now because the gas shouldn't enter the rest of the house. I've noticed that air purifiers and occasionally blasting ozone also work well.
Why am I writing this?
First, I strongly advise against all theories of passive houses without dehumidification/ventilation and a heat source. These are always needed.
But I have a question regarding the choice of insulation and diffusion. I'm starting more and more to realize that I don't understand everything,,,
Diffusion-tight (like Foam) is good if you have a hurricane-FX ensuring below 55% (type) everywhere. But yeah, ,,,
Diffusion-open actually has the advantage that it is always possible to drive out moisture. In both directions. Very flexible and self-regulating. The problem then becomes the choice of material. There are different types of multipor that are completely organically dead (unlike mineral wool actually). But then someone wallpapers or paints with junk paint that is tight and,,, yes mold. The best would be concrete that breathes and also insulates a bit.

The problem is that the moment you have insulation, you almost always get a point against the outer wall where moisture and mold form.

I want to emphasize that several react quite significantly to mold gas and enzymes. Among others, allergy sufferers. Mold occurs in new bathrooms and everywhere as soon as RH is just over 70%. The problem is that you can't sand or wash away mold (see Ljungby) - it just results in other worse effects. The only option is to tear out the stuff but that usually gets cumbersome.

So, those of you insulating basements and garages (internally), how do you reason? Especially those who've had a few houses or have followed projects from start to finish. Old mold damage that doesn't grow - can it remain as long as you purify the air and remove it?

 

[kettu]

A little mold in a house will always be there, it can't be completely removed.

Mold detection dogs are poor tools if people are otherwise healthy and without issues in a house, in my opinion.

An example: We had a mold detection dog sniff a house we were interested in. The dog marked in front of the sauna stove. Most likely because wood had been there during/after a sauna bath. The owner hadn't used the sauna for several weeks, but the dog sensed a little mold smell from the wood that was there.

Their sense of smell is too sensitive to use if you otherwise have a "healthy" house. This can lead to paranoia and expensive and unnecessary work.

 

[RSRC]

Some mold in a house will always be present, it cannot be completely removed.

Mold detection dogs are poor tools if people are generally healthy and without issues in a house, in my opinion.

An example: Had a mold detection dog smell a house we were interested in. The dog marked in front of the sauna stove. Most likely because firewood had stood there at/before a sauna bath. The owner hadn't used the sauna for several weeks, but the dog detected some mold scent from the wood that was there.

Their sense of smell is too sensitive to be used if you otherwise have a "healthy" house. This can lead to paranoia and expensive as well as unnecessary actions.

Thanks. In this case, there have been some sneezes and other symptoms. But absolutely you are right - it's enough for the firewood pile by the fireplace to stand for 1-2 days on a plastic for mold spores or if it’s the gas.
I have noticed how great the psychological effect is - for better and for worse.

 

[kettu]

Thank you. In this case, there have been some sneezing and other symptoms. But absolutely, you're right - it only takes the woodpile for the open fireplace to have stood 1-2 days on a surface for mold spores or if it's the gas.
I've noticed how strong the psychological effect can be - for better or worse.

I can respond from personal experience. We have been living for 1.5 years in a house built in 94 with FTX. Some time after we moved in, we thought the air was a bit too poor to have FTX. I am personally afraid of mold, so the first thing I did was bring in a mold dog. It marked in both bedrooms and in the kitchen as well as the shower.

We brought in a moisture expert and he investigated. In the kitchen corner, we found black spots on the gypsum wall, behind a cabinet. But the wallpaper that ended over it was unchanged, so he concluded that it happened during the construction stage when they poured/ground the concrete.
In the bedrooms, the FTX is blown in, and at that time took the air from the attic.

Well, the only thing I've done is to draw outside air to FTX to make it fresh. Set it in negative pressure.
Even though the dogs declared our "new" house a mold bomb, we haven't had the slightest symptom at all. Even someone who is mold-sensitive didn't react with us. So the dogs are a little too sensitive to mold smell.