Smart ways to lower house humidity?
We are seriously considering moving our laundry room to the 2nd floor, near the main bathroom, where water service is easy to tap into. My house is old and not yet very air tight: soon to be installed a new steel metal roof, and below that a air & thermal barrier.
Still, I worry about the excess humidity given off by modern activities – showers, washers & dryers. Our new heat pump clothes dryer will greatly reduce humidity over a typical clothes dryer. We use simple wooden drying racks to reduce energy consumption and am considering a European-type clothes drying closet too.
But what about the humidity thrown off by the shower and the clothes washer? I’ve read on this website code requirements – bathrooms must have a window or be vented to the outside. I presume this requirement was established to protect interior wall assemblies from absorbing excess moisture, with attendant risk of mold and wood rot. But such venting seems so “last century”. I know there are smart vents, such as Lunos e2, but are there better, perhaps “tighter” ways to precipitate ambient water vapor and carry it off? Why not simply install a tight door seal in an enclosed glass shower closet – to trap the “steam” of a shower within an enclosed space? Or how about a small quiet dehumidifier – attached to bath vent? Does any one make such an appliance? Are there other ways to get at this problem?
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Replies
There are through-wall ERV units that serve just one room. No firsthand knowledge.
The calculus is whether it is more efficient to condition the hot humid air in the bathroom or vent it and replace it with air from outdoors and condition that air. In the winter there typically is no dehumidification going on so the only choice is to ditch the hot, humid air. In the summer the outdoor air is typically cooler and dryer than what's in the shower.
A sealed shower enclosure is a good idea to contain the humidity.
In all but the tightest houses, overall humidity in the winter is usually lower than optimal. Redistributing that humidity would be a better strategy if there was a way to diffuse and control it.
A properly installed washer and dryer shouldn't be introducing humidity into the living space.
Dan,
I'm not sure a new code compliant house doesn't already do the things you are suggesting. A correctly sized bathroom fan, or HRV on boost, will ensure excess humidity is exhausted before it affects the rest of the house. Conventional clothes dryers exhaust most air to the outside leaving laundry rooms if anything dryer then the surrounding ones. The ambient indoor humidity levels and air quality can be controlled by full time balanced ventilation. What's left to worry about?
"My house is old and not yet very air tight."
Dan seems to be asking why there aren't new more efficient methods of dealing with moisture in houses. My reply was that what is presently used works fine without need for any gymnastics.
I agree with you though. It's unlikely the house has or will have a humidity problem until it gets tightened up.
On a side note. If you're considering a front-load washing machine pay attention to the deflection of the floor in proposed bathroom area. If the floor is bouncy the FL-washer can "walk".
Top loaders can do that too. I have that problem right now myself: the spin cycle rattles things on the shelves on the opposite wall of the laundry room. Since I’m planning to tile the floor, I’m a bit concerned with the bounciness. I’m going to be sistering all the joists (only 8 of them) to hopefully cure the problem. The MSR lumber was just delivered this past Saturday in fact. Now I have the fun of maneuvering 16 foot long 2x10s into the basement...
Bill