Moisture control in the winter

This house is too dry. This house is too humid. This one is just right!


Published on 18 Feb 2021

Can your home be too dry?

Most of us in the upper Midwest are very familiar with the signs of condensation when temperatures suddenly fall as winter sticks its boney finger in our collective eye. All you need is a little too much moisture on the inside of your home, a dramatic difference between room temperature and outside temperatures, and suddenly water begins to collect on the window frame—condensation! Not good.

Most of us are afraid of creating a jungle-like atmosphere that could breed bacteria and mold. That makes sense. But what happens when your home is too dry? Nothing good.

"It's fun until somebody gets hurt!" — Mom.

Think of yourself stranded in, say, the Sahara desert, or the Gobi, either one. You’re there for a whole day. No shade, no water. Not good, right? The same thing happens to your home when it’s too dry. Without the camels of course.

While you might get an occasional nosebleed or a static shock robust enough to bring Frankenstein back to life, your furniture, doors, windows will also suffer. Paint and drywall cracks can appear, furniture and acoustic instruments can be adversely affected, and cabinet doorframes can begin to separate.

It's not just about damage to your home, but about healthy living conditions.

So what is the ideal humidity level?

Most energy experts would agree that the healthy moisture level within a residential home is between 35-55%. Okay, that’s a pretty big range, but that’s because you may need to have higher humidity for such things as sensitive instruments, like pianos and cellos. As a general rule for optimal health it is recommended that your home humidity level be around 45%.

If you've consistently got 70% humidity in your home, mold monsters are probably awaiting your return from the grocery store.

So how can you know for sure what your humidity level is in your home?

You could get a hygrometer, which calculates relative humidity. They can be a little spendy though, $50 - $100, especially if you get the ones that also tell you when your steak is done on the grill. However, it might be worth it. You would be held in high esteem among your neighbors as the only one on the block with such vapor-minded acumen.

The "Ice Test" should not be conducted with good Scotch as that should always be consumed neat.

You could always go the low-tech way with something called the "ice test." Put three medium ice cubes in a glass of water and stir it a few times. Wait for 180 seconds. Actually, roughly three minutes also works, but being exact makes it sounds more scientific. If you see droplets begin to form on the exterior of the glass, your home has normal to higher humidity. If no droplets form, then, you’re environment is too dry. Not quite the Sahara, but you’re heading in that direction.

What can you do to control humidity in your home?

Make sure your bathroom has an up to date exhaust system that efficiently and quietly vents moisture to the outside—same for your kitchen. A properly installed HVAC system should be able to control the moisture in your home, if all other envelope aspects are in good shape. Adding a humidistat can be a quick fix to an overly dry condition, but looking at larger issues is always recommended.

The average human breaths about 4 cups of water into the home each day.

You could always tell your teenager to take an extra long shower (as if you’d need to) or for an even quicker fix with gastronomic benefits, you could make spaghetti more often if a lack of moisture is the issue. There are a number of ivy and fern plants that supposedly absorb more moisture than they give off, but that seems more like a way to support nurseries than solving moisture issues.

“Inspecting your vapor barriers, attic, and wall insulation, cracks in foundation walls and grading, windows, the condition of your siding and even soffits can have a significant impact on your moisture levels,” explains owner John Murphy. “These are not quick fixes, but they are real long-term solutions that should absolutely be considered.”

Texas apartment showing burst pipes flowing through ceiling fan. Photo: Thomas Black

So why are homes in Texas having such difficulty?

The recent cold snap in Texas just underscores the importance of your home’s envelope in controlling moisture. Their construction methods are very different than ours in Minnesota, where controlling moisture in temperature extremes is the name of the game.

“Some people I’ve talked to this week are actually experiencing water running out of their electrical outlets because they do not have the same vapor barrier practices that we do here,” said Murphy Bros. project manager Drew Johnston. “It’s pretty scary really.”

So, should water spots suddenly appear in your ceiling in a few days or weeks when temps soar above freezing, don’t freak out. Read the blog we wrote on that subject, then take two aspirin, and give us a call in the morning.