3 ms·

I am a little confused about this fear people have of mold and mildew in their houses. Up until very recently people's houses weren't far off from the outside e

I am a little confused about this fear people have of mold and mildew in their houses. Up until very recently people's houses weren't far off from the outside environment. Generally in the summer the best they did was keep the rain out and provide some shade. Houses weren't uninhabitable mold pits back then, why would they be now?

AngryData 7y ago
There is some additional risk with modern homes being much better sealed than old homes which always had some air moving through it. If you don't have a proper HVAC system and use like electric heaters instead of forced air, humidity levels can build up and slowly absorb into materials if you don't have enough airflow, and you likely won't notice, unless maybe the dew point gets high enough that all of a sudden every surface in your house is damp. It is less of a concern in places without high humidity but some swampy areas can be 90% humidity for weeks or months at a time and then all of a sudden you got mold behind your walls because some idiot decided to seal up every seam with plastic or glue or whatever other impermeable material. Part of this is a misunderstanding of building techniques that block airflow, ive seen numerous houses with all the roof vents plugged up to "save heat", walls with plastic sheeting on the inside wall creating air/moisture traps, or people replacing air-permeable house wrap with solid sheet plastic, foam and glue on every board and seam with a sealed up and moist crawl space underneath, ect. It is fairly easy to get mold in a humid place with a sealed home and no forced air, and nearly impossible to kill it all without tearing out all the drywall in the house. If everything was done right, shouldn't be a problem, but people are far more likely to pay for size and speed over quality materials or careful quality labor.
- fhsm 7y ago
  Here’s an accessible and illustrated page with some additional details around your point https://www.popularmechanics.com/home/interior-projects/how-to/a149/1275121/ https://www.popularmechanics.com/home/interior-projects/how-... I’ve seen this turn into a problem with big renovation of old residential structures twice. My personal takeaway was make sure your envelope and HVAC are of roughly equivalent quality and era.
rags2riches 7y ago
It is actually easy to ruin a home by trapping moisture using modern materials carelessly. It happened to many centuries old buildings in the twentieth century after being renovated and modernized to save on heating. Traditional techniques allowed more circulation of air that avoided mold.
dagss 7y ago
Well just as an example, around here concrete cellars were usually not insulated before. They were storage areas. In the 80s people started insulating them in the wrong way (on the inside), creating a condensation point between the insulation and concrete => mold. These days we have learned that cellars must be insulated on the outside (by digging up the garden) or somehow make sure humid indoor air dont make contact with concrete behind insulation. If you basically don't have plastic and insulation then mold is less of a problem, but you also need to spend a ton of energy keeping the house warm...
krisoft 7y ago
Well exactly because of that. If your house has plenty of air circulation (that's what "people's houses weren't far off from the outside environment" means) then things might get damp, but they will also dry out naturally too. Now you get a huge plastic bag and wrap it around a building. It will keep out rain yes, but also trap in moisture internally and the damp parts will get mouldy. Obviously nobody will do something as silly as that, but with modern materials it become much easier to accidentaly approximate the plastic-bag-wrap experience.
fulafel 7y ago
There's lots of things we don't understand about the health interactions, but even if you don't suffer ill effects at least you'll risk stigma if you and your clothes smell of mildew. It's sometimes hard to imagine how hard and unprecitable lives of past generations were. For most of history people's indoor firepits didn't have chimneys, for example, and the health effects were less of a concern than wars, infectious diseases, getting hurt in physical labour, or famine. Also, most old houses were well ventilated and built of mildew resistant materials (= poor insulation and wood).

AngryData 7y ago

There is some additional risk with modern homes being much better sealed than old homes which always had some air moving through it. If you don't have a proper HVAC system and use like electric heaters instead of forced air, humidity levels can build up and slowly absorb into materials if you don't have enough airflow, and you likely won't notice, unless maybe the dew point gets high enough that all of a sudden every surface in your house is damp. It is less of a concern in places without high humidity but some swampy areas can be 90% humidity for weeks or months at a time and then all of a sudden you got mold behind your walls because some idiot decided to seal up every seam with plastic or glue or whatever other impermeable material. Part of this is a misunderstanding of building techniques that block airflow, ive seen numerous houses with all the roof vents plugged up to "save heat", walls with plastic sheeting on the inside wall creating air/moisture traps, or people replacing air-permeable house wrap with solid sheet plastic, foam and glue on every board and seam with a sealed up and moist crawl space underneath, ect. It is fairly easy to get mold in a humid place with a sealed home and no forced air, and nearly impossible to kill it all without tearing out all the drywall in the house. If everything was done right, shouldn't be a problem, but people are far more likely to pay for size and speed over quality materials or careful quality labor.

fhsm 7y ago
Here’s an accessible and illustrated page with some additional details around your point https://www.popularmechanics.com/home/interior-projects/how-to/a149/1275121/ https://www.popularmechanics.com/home/interior-projects/how-... I’ve seen this turn into a problem with big renovation of old residential structures twice. My personal takeaway was make sure your envelope and HVAC are of roughly equivalent quality and era.

rags2riches 7y ago

It is actually easy to ruin a home by trapping moisture using modern materials carelessly. It happened to many centuries old buildings in the twentieth century after being renovated and modernized to save on heating. Traditional techniques allowed more circulation of air that avoided mold.

dagss 7y ago

Well just as an example, around here concrete cellars were usually not insulated before. They were storage areas. In the 80s people started insulating them in the wrong way (on the inside), creating a condensation point between the insulation and concrete => mold. These days we have learned that cellars must be insulated on the outside (by digging up the garden) or somehow make sure humid indoor air dont make contact with concrete behind insulation. If you basically don't have plastic and insulation then mold is less of a problem, but you also need to spend a ton of energy keeping the house warm...

krisoft 7y ago

Well exactly because of that. If your house has plenty of air circulation (that's what "people's houses weren't far off from the outside environment" means) then things might get damp, but they will also dry out naturally too. Now you get a huge plastic bag and wrap it around a building. It will keep out rain yes, but also trap in moisture internally and the damp parts will get mouldy. Obviously nobody will do something as silly as that, but with modern materials it become much easier to accidentaly approximate the plastic-bag-wrap experience.

fulafel 7y ago

There's lots of things we don't understand about the health interactions, but even if you don't suffer ill effects at least you'll risk stigma if you and your clothes smell of mildew. It's sometimes hard to imagine how hard and unprecitable lives of past generations were. For most of history people's indoor firepits didn't have chimneys, for example, and the health effects were less of a concern than wars, infectious diseases, getting hurt in physical labour, or famine. Also, most old houses were well ventilated and built of mildew resistant materials (= poor insulation and wood).