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Found out my house is basically a giant sponge for water vapor | DIY Home Projects - nhfree.com

adam9•5mo ago

Found out my house is basically a giant sponge for water vapor

I was redoing the bathroom in my 1950s ranch last month and got curious about the old plaster walls. Did some digging online and found a study from the University of Minnesota building science lab. It said an average house in a humid climate can absorb and release over 50 GALLONS of water vapor into the air over a single season, just through the building materials. My mind was blown. I always thought my walls were just... walls. Now I'm looking at the old lath and plaster totally differently, like it's this breathing, living thing. It explains why the place feels so muggy in July. Has anyone else stumbled on a weird fact about their home's construction that changed how you see a project?

4 comments

4 Comments

thomas_gonzalez5mo ago

That part about walls being a "breathing, living thing" really hits home. I always just saw my old walls as a solid barrier, something to hang pictures on. But learning how much moisture they hold and release makes me look at my whole house differently now. It's not just a box, it's a system that reacts to the weather. Makes me wonder if I should be more careful about sealing up drafts or if that would trap all that moisture inside.

dakotacraig4mo ago

Actually the vapor barrier idea works better in colder climates where you want to stop indoor moisture from getting into the walls in the first place. In warmer humid areas like Florida you're usually better off letting the walls dry to the inside too, so sealing everything up can backfire. Are you in a mixed climate where you get both cold winters and humid summers?

the_blair5mo ago

My uncle in Florida sealed his house up tight as a drum to save on AC costs. He ended up with mold in the walls within two years because the moisture had nowhere to go. Thomas_gonzalez, that's the exact worry with over-sealing an old house. Those drafts in older places are often part of the design, letting the walls breathe out that moisture you're talking about. Making a house too perfect can sometimes cause bigger problems than the ones you're trying to fix.

sean_walker454mo ago

Ever thought about looking into a vapor barrier instead of full sealing? I had the same worry with my 1920s place after I sealed up some leaks and got condensation forming on the windows. Ended up putting a smart vapor retarder in the attic and it made a huge difference letting the walls dry out while still keeping the drafts down. You definitely don't want to trap moisture, but a little airflow and the right vapor control can let you have both.