Dehumidifying a bathroom
I have a 8′ x 8′ 2nd floor 3/4 bathroom (shower, toilet, sink, but no tub) with no window. Paint peals from ceiling and un-tiled upper walls presumably because of moisture from the shower. I’ve been thinking of replacing a broken ceiling fan that currently vents to the unfinished 3rd floor (not to the outside). Venting to the outside is a poor option: it introduces an air gap in conditioned space, and a solid standing seam metal roof and soffits that are enclosed at the top of 20″ stone walls make venting a difficult choice. Instead, I am considering a small wall/ceiling dehumidifier unit in the bathroom – one that would remove excess moisture and pump drier air back into the bathroom. Would this work? Would a dehumidifier rather than a vent be consistent with code requirements?
Would a small mini-split HVAC system be a better choice than a dehumidifier or just more expensive? The house is heated from an modern oil fired boiler connected to a radiator hot water system; 2nd floor air conditioning is a high velocity system.
Are there passive methods for dealing with bathroom humidity, that do not entail venting? For example, if the entire room were tiled, and wet surfaces were wiped down after each hot shower, would that protect structures from excess humidity? You hear of indoor saunas: how do they manage heat & humidity?
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