We have recently had 1/2 of our basement finished. The walls are gyprock and most of the ceiling is a suspended type. There is no cold air return to this room but there are 3 adjustable air vents (screw type) in the ceiling. We had a rug installed over a foam chip underpadding (the foam supposely OK for basements).Regardless of whether it is in the middle of the Summer (we have air conditioning) or in the Winter, it seems that if there are 3 or 4 people in the rec room for over an hour, there is a musty (sweaty?) smell to the room. After the room is vacated an hour or so the smell disapates. I have called a couple of air quality specialist firms and for a price ranging from $250 to $500, they will send someone over to take some air quality measurements. Could you suggest why this problem occurs, going from most likely to the least. Note: Our basement before it was finished had no "water" problems, i.e., leaks.
Answer:
The underpad and/or the carpet but most likely only the underpad is holding on to atmospheric moisture. Try this for something under $100.00: Cold air holds more moisture than warm air and is, therefore, heavier. As air cools, it falls and keeps falling until it reaches the lowest level in the house. It cannot fall beyond the basement floor and that is where it has to be collected and pumped outside before that moisture gets a chance to condense in order to get rid of the moldy, musty odour and/or avoid it in the first place. A booster fan (250 CFM +) is available as a ‘pop in’ unit to fit 4”, 5” or 6” round heating duct. This can be installed in a totally separate duct line that is at least six feet from the nearest heat source. A timer on it will ensure that it operates only during the night (9pm to 9am) so cold, moist air it pumps out is not replaced by air that brings in even more humidity from outside. All joints and seams in the duct are taped and sealed for maximum efficiency and rather than a heating-type grill it should be a return air-type grill. To avoid having to core another hole in the foundation wall, this system can be vented, via a “TY” through the clothes dryer vent. Because none of the doors in the house go all the way to the floor, cold, moist air should find its way to that grill.
