Mold is not a ventilation problem, but rather a moisture control problem. Keep the humidity down (especially with whole house dehumidifiers), and eliminate condensation points (by eliminating thermal bridging), and it goes away.
While the above video, which is from the really good channel by Matt Risinger, is a good introduction, I recommend you also check out the building science stuff put out by Joseph Lstiburek for a more science-y explanation:
> Mold is not a ventilation problem, but rather a moisture control problem. Keep the humidity down (especially with whole house dehumidifiers), and eliminate condensation points (by eliminating thermal bridging), and it goes away.
This sounds like one of those kinds of answers that only works with spherical cows in a vacuum.
If my shower were completely open and in the middle of the living room, perhaps. Alas, it's in a small private room that usually has the door closed while in use, and now we've circled back around to ventilation...
> A house should not breathe
Well - first you have to define what "breathing" is, because I've talked to tradesmen who thought it meant allowing air in and out...
Closer to the correct definition shared amongst building scientists is to allow the passage of water vapour. Many engineers would disagree with the approach of having non-breathable walls. If you're renovating old properties you are putting a LOT of faith in your VCL if you go this route.
I like the concept of breathability personally, allied with high air tightness. But you have to use the right materials and, crucially, install it right.
However, if you're doing an air barrier, you can often get a moisture barrier "for free" nowadays. Since a lot of housing uses OSB/plywood, if you go with something like Huber's Zip System--which has a coating on it--you can save a lot on labour by only doing one pass around the house. Though you do have to seal the seems as well.
Otherwise something like the popular Tyvek will get the job generally done, but there are peal-and-sticks as well that tend to be tighter (and vent as well, like Delta Vent).
If one is okay with the cost, there's also the idea of simply closed cell foaming the entire house. :)
* https://www.youtube.com/watch?v=CIcrXut_EFA
Mold is not a ventilation problem, but rather a moisture control problem. Keep the humidity down (especially with whole house dehumidifiers), and eliminate condensation points (by eliminating thermal bridging), and it goes away.
While the above video, which is from the really good channel by Matt Risinger, is a good introduction, I recommend you also check out the building science stuff put out by Joseph Lstiburek for a more science-y explanation:
* https://en.wikipedia.org/wiki/Joseph_Lstiburek
On the "perfect wall":
* https://buildingscience.com/documents/insights/bsi-001-the-p...
Presentation on control layer (especially starting around 15m):
* https://www.youtube.com/watch?v=rkfAcWpOYAA
Good webinar:
* https://www.youtube.com/watch?v=sBcNFeiWjrg