I have a client that built an ICF Condominium where some of the tenants are concerned with interior moisture.  Upon visiting the condo today there is obviously to much moisture (although it has been very cold here).  The question is this, does anyone know if it is possible to remedy this structure being to tight, without putting in an air exchange.  The air exchange would be very costly.  Perhaps a dehumidifier in the HVAC, education for owners, stand alone dehumidifier, or another option?

Any ideas or answers are greatly appreciated.

Thanks,

Ren

Ren,

Here in the Pacific NW moisture is always a big concern. Besides sunny Seattle getting its fair share of rain and high humidity, you add to that all of the moisture everyone adds to their home everyday and it equates to gallons of water. We install good quality air exchangers with a heat recovery system on all of our buildings. This is truly the best answer for us. Some contractors I know will put timers on the fans in the baths and kitchens that kick on at certain intervals to try and get the 6 air exchanges an hour needed to promote a healthy indoor environment.

What type of HVAC system do the condos use? (Forced Air, raidiant, other)

Educating the consumer is always important also. Any time they are cooking, showering, doing laundry, and such they need to run their fans to exhaust as much of the excess moisture as possible being created a that time. They should also let the fans run for at least a half hour after the activity is finished.

Hope this helps

ICF Contractor

renangle
If the HVAC unit is not sized properly for the house and if an air exchanger is not built into the system you will have moisture build up and can eventually have a sick house.
The sick house syndrome is not always a given because of the life style of the people that live in the house.
The moisture build up is probably due to the fact that the Air Handler is not running long enough to take the moisture out of the house. The unit is probably to big and shuts off to soon.
In the cold portions of the county the outside cold air will not hold much water vapor and if you bring in the cold dry air in small amounts and exchange it for the warm moist air in the home then you can maintain a relative humidity of 45 to 50% and mold will not grow. Warm air will absorb moisture from showers, baths, flower vases, any open vessel that holds water, even coffee cups.
The owner is going to have to deal with the problem or face the major expense of remediation of mold growth in all of the units. The most economical method is to install the correct size AC units and air exchangers. But he probably wont do that so his next best solution is dehumidifiers. He will have to put in drain lines and run the units 24/7. That will drive the electric bills up and he will have to listen to the tenants complain. He can also plan on one or two of the tenants shutting the humidifiers off for one reason or another and the unit will go to mold.
He can pay a bunch now or a whole buch later. His choice.
Regards,
Joe