Hi everyone, 
    I am new here, I just recently built my own home in CT. Here we are climate zone 5A (cool humid). Mostly cold dry winters, but as of the past few years very humid winters, and very humid summers. I took a new approach in building my home, it resembled an article I saw listed on JLC. Here is the link https://www.jlconline.com/how-to/insulation/an-airtight-lid-the-easy-way_o 
     My home is a 2400 sq ft ranch with 8’ walls and one cathedral ceiling (13’ to the peak). I built the house in the same manor but without the use of exterior insulation. I would have finished off my attic space but could not afford the added expenses that came along with that. When I began construction it was shortly after the lumber plummeted in 2022 so I took advantage of the market and decided to plywood my entire attic deck with zip. Unfortunately at this time rigid foam board and rockwool comfort board skyrocketed in price in my area and I could not afford to go that route.
     My wall assembly is constructed as follows from the outside in.
7/16 zip 
2×6 studs 16” OC w/ r-23 rockwool 
certainteed membrane as a vapor retarder (I am not a fan of poly) 
1/2 Sheetrock 
I followed the same order with the ceiling . I basically built a second floor in my house where all of my ceiling joist are 2x10s that are filled with r-15, and r-23 rockwool to achieve r 38. My joist sit on top of my exterior walls along with a rim joist. The exterior sheathing runs to the top of the joist where it was taped to the attic zip decking. From there I laid a 2×6 plate and stacked my rafters on top. The whole roof is a vented attic with vented soffits and ridge vent. 
    I followed the same concept with my vaulted ceiling actually building a roof within a roof. I dropped the vaulted ceiling into the room by attaching a ledger on the inside of my walls and hangered the rafters from there. I sheathed this roof before installing my main rafters. I taped all the zip seams to the attic floor and installed a vapor diffusion port at the ridge leaving the plywood 2” down from the ridge and draping tyvek over it and taping to the plywood on all sides. The vaulted ceiling consists of 2x10s 24” OC with r-30 rockwool and 2” of eps foil faced foam facing the heated side of the room. I cut and cobbled the eps making sure it was tight and taped the seams with foil tape because this was my vapor barrier for the ceiling.  The vaulted ceiling roof deck is 1 1/2” away from the bottom of the actual rafters. I have never felt or noticed any moisture at the diffusion port. 
     My energy bills have been extremely low. I heat and cool my home with a 4 ton heat pump and average $45-150 monthly electrical bill HVAC aspects depending on the seasons. I have not moved in and am currently in the stage of final construction, floors are being finished.
     My only concern is the humidity levels in my home. As winter is moving in my windows and doors will condensate even though they are double pane andersens with .26 u factors.  I took extreme care air sealing and insulating this house thinking I was doing a good thing. I have a full continuous air barrier, the zip wraps the entire envelope and is liquid flashed to the foundation. Now in the winter time the humidity always likes to hover around 50%+-. I understand stagnant air becomes very stuffy and humid if fresh air is not supplied. I have bath fans I use and crack some windows and a Fantech 750 MAUS makeup air kit for my kitchen exhaust hood. This will drop the humid very fast with all the fresh air brought in. Today I installed a Broan AI Erv tied into the return of my air handler. I have not been able to run it long enough to see how much of a difference it makes but I assume it will be much better.
     I constantly have to run a dehumidifier in the unfinished basement
basement to keep the humidity down. I did install a vapor barrier below the slab before I poured the floor, I also installed footing drains with foundation waterproofing, so it never gets wet inside just the humidity rises. My first floor are 2x10s filled with r-30 rockwool and 3/4 advantech glued and nailed (no vapor barrier for the rockwool the inspector has been fine with this). 
     Is my attic to tight not letting the humidity rise into the vented area and relieving the moisture. I was not worried about this when building thinking that zip is somewhat permeable (at least Huber says it is 3perms for osb and 13 for the WRB or so) and I have the certainteed memebrain so it could dry to the inside if saturated. I have not recently pulled up the plywood to check if there is any moisture or mold on the underside because it is all taped. In October on a very cold day I did check before I taped it, and a 16”x16” piece of zip had little to no moisture on the underside (this was around 55% humidity in the house).
     My blower door test is next week but I’m assuming I’m well below 1ACH. Am I too worried about the attic plywood? I thought it would be a good idea having the continuous air barrier along with all the extra storage. Or is it too early to tell without having the full use of the erv to circulate the fresh air and balance the humidity? I just wanted to do what I thought was best but am stressed thinking I’m going to have a constant risk of mold on underside of the attic plywood especially in the winters.
    Any insight would be greatly appreciated, thanks