Don K wrote:

Airseal it well, then add a humidistat and a fan to move at least
200 cfm of air from the basement floor upstairs whenever the RH
near the floor is more than 60%...

How would you check whether you have sealed the house too well?

That's extremely hard to do, in practice, akin to turning your house
into a boat. The RH would climb to 100% with condensation on windows
inside a completely airtight house.

An airtight house is a recipe for sick building syndrome.

Nonono. You are completely wrong. It's a recipe for a happier healthier
building and occupants with lower energy bills, according to one Canadian
R2000 home study. These homes have "mechanical ventilation systems," eg
humidistats that turn on small exhaust fans. The R2000 standard does not
require ERVs or HRVs.

Unless they like to design such systems as a science project or hobby,
it's more effective for the average person to just fix the problem
by using a dehumidifier.

Nonono. You are completely wrong. Witness soaring Humidex sales, in spite
of their $1K price tag and less-efficient outdoor exhaust. I installed a
basement-floor-to-upstairs circulator in a house yesterday, in about 20
minutes, using a $4.95 humidistat and a $12 window box fan.

Nick