House built on spec in 1999. I’m the HO. You get a long stretch of cold weather followed by a slight warm spell, and it starts to rain indoors. In the latest incident, the smoke detectors go off. Turns out one of them is full of water. It’s got an A/C duct above with insulation full of ice that’s thawing (attic temp was 18 degrees F at the time).

This is ridiculous. The only thing that really works is sealing up all the registers (standard square ceiling) with plastic and tape.

The ductwork is tin for trunks and long runs, with flex to the registers. It appears that none of the joints in the tin were sealed, as air leaks through any hole in the insulation when the system is running.

I’ve looked around for registers that truly seal when you close them, but no dice. Does anyone know where you can get covers that seal well and are relatively easy to put on?

I’m inclined to rip all the insulation off the ductwork and seal the ducts next summer, if nothing else just to reduce the amount of A/C that’s leaking. There’s no way the system will be airtight though, so I think I need a better way to control condensation. Any ideas?

Also, any recommendations on the appropriate amount of insulation? Right now, the trunks are covered with 1/2″ foil-faced glass, and the ducts are either flex or round duct inside flex.

Pete