Certainteed windows are good, Consumer reports tested alot of windows ,
one test was condensation, I have pella and anderson , the pella fog ,
anderson dont, see how they rate yours.
Humidity acuracy is tougher, so you put yours outside and it
corresponded to the tv. It may work. And be right. But Im Quoting
Taylor instruments now;
" Humidity meters measure relative air mosture indoors only, not the
outdoor humidity reported by the weather bureau. These instruments
register percentage of water which is actualy present in the room
compared with the maximum amount of water vapor that could be present. "
If yours is correct that is a safe level. but that also depends on
outside temps and humidity, if you are in the dry cold now id say you
are to high , im 50` and raining and im at 51% , and my house IS to
tight. but i dont condense on pellas till 20 outside, at night. I
still think you have a tight house. I can lookup some numbers on RH vs
Temperature , how cold is your area now. I put foam board on , new
windows , the whole works. Last year i couldnt run my new April Air
automatic humidifier, im to humid now. Now I need a fresh air recovery
system, or a second dehumidifier . I am getting a scond blower test. You
save money by insulating, but can create a new issue.