Central Texas Humidity Guide: How to Keep Your Home at 50% or Below

Quick answer: Keep indoor humidity between 40% and 50%. In Central Texas, that usually takes a hygrometer to check the number, the thermostat fan on "Auto," bath and kitchen fans that vent outside, and a whole-home dehumidifier when the AC can't keep up.

What humidity should an Austin home have?

Indoor humidity is the amount of moisture in your home's air, shown as a percentage called relative humidity. Above about 50%, a home starts to feel sticky. Fabrics, carpets and dust hold more moisture, dust mites thrive, and microbes settle more easily into closets, bathrooms and the cool spots near vents.

All of that raises your home's bio-load: the microscopic particles that build up in the air, on surfaces and in the HVAC over time.

Staying at or below 50% here takes work. Gulf air keeps Austin's summer dew points high for months, and that moisture slips in every time the garage door opens, through gaps around attic stairs and recessed lights, and from every shower and pot of pasta.

Why can't my AC keep up with the humidity?

Your air conditioner does remove moisture. As warm air passes over the cold indoor coil, water condenses and drains away. But in Austin, the AC often falls behind in four situations.

Spring and fall "shoulder seasons"

From March through May and again in October and November, Austin often pairs mild temperatures with muggy air. The thermostat is satisfied quickly, so the AC barely runs. When it doesn't run, it doesn't pull moisture out, and the house feels cool but clammy.

Summer nights and rainy stretches

On a cooler night or after a storm, the temperature drops but the moisture stays. The AC runs less, and the humidity creeps up.

An oversized AC that short-cycles

A system that's too big for the house cools the air fast, reaches the thermostat setting in a few minutes and shuts off. That's called short-cycling, and Austin's long muggy season exposes it more than a dry climate would.

The coil needs to run cold for a while before it pulls much water out of the air. Short cycles cool the air but leave much of the moisture behind. If the fan keeps blowing after the compressor stops, water on the coil evaporates right back into the house. The result is a home that's cold, damp and uncomfortable.

Other common causes

• A thermostat fan set to "On" instead of "Auto," which blows coil moisture back into the house
• Leaky return ducts that pull humid attic air into the system
• A dirty coil or clogged filter that cuts airflow
• Bath and kitchen fans that go unused or vent into the attic
• A damp crawl space under a pier-and-beam house
• A newer, tight home with little fresh-air exchange

What are the signs of high indoor humidity?

The house usually tells you before a gauge does. Watch for:

• A sticky or clammy feel, even when the house is cool
• Fog on the inside of windows on cool mornings
• Condensation or "sweating" on air vents or around the grilles
• A stale or musty smell, especially in closets or when the AC starts
• Bathroom mirrors and walls that stay damp long after a shower
• Wood doors that stick or floors that feel tacky
• A thermostat you keep lowering without ever feeling comfortable

How do I check my home's humidity?

Use a hygrometer, a small, inexpensive gauge that reads indoor humidity. Hardware stores carry them, many digital thermometers include one, and some smart thermostats show humidity too.

• Place it in a main living area, away from the kitchen, bathrooms and direct sun.
• Check it at different times of day for a week or two.
• Add a second one to a bedroom or any room that always feels damp.
• Act if you regularly see readings above 50%.

Which everyday habits lower humidity?

• Set the thermostat fan to "Auto," not "On." Our guide to HVAC fan settings explains why.
• Run bath fans during showers and for about 20 minutes after.
• Use the kitchen hood when cooking, especially when boiling water.
• Change your HVAC filter every 1-3 months.
• Keep doors and windows closed on humid days.
• Dry laundry fully and make sure the dryer vents outdoors.
• Fix drips and leaks under sinks and around the water heater right away.

Do I need a whole-home or a portable dehumidifier?

When habits and your AC aren't enough, a dehumidifier is the next step. Our guide to choosing a dehumidifier goes deeper.

Stand-alone (portable) dehumidifiers

These plug into the wall and sit in one room.

• Good for: one problem room, a closet area or a garage workshop
• Downsides: they only help the room they're in, need their bucket emptied (unless you set up a drain hose), can be noisy, and add heat to the room

Whole-home dehumidifiers

A whole-home dehumidifier is installed as part of your HVAC system. It pulls moisture from the air for the entire house and drains automatically.

• Good for: homes that feel damp in several rooms, oversized AC systems, tight newer homes and homes with long shoulder seasons (which is most of Central Texas)
• Upsides: quiet, hands-off, controls humidity even when the AC isn't calling for cooling, and lets you feel comfortable at a slightly higher thermostat setting

Our sister company Gold Eagle Services installs whole-home dehumidifiers and can also check whether your AC is sized right, clean your coil and seal leaky ducts.

How does humidity affect your home's bio-load?

A house held at 50% or below gives dust mites and microbes less to work with, so its bio-load builds more slowly. If your home ran damp through a wet spring or a summer with an undersized dehumidifier, a whole-home dry fog treatment can give it a fresh start once the humidity is under control.

Our patented Pure Maintenance VaPURE dry fog floats instead of wetting things, so it follows the same paths damp air took: into closets, behind furniture and through the HVAC ductwork. It helps neutralize the stale smell a damp season leaves on treated hard, non-porous surfaces. The job takes one day, and we ask you to set the AC to 68 beforehand, which also pulls some moisture out of the house.

We don't measure or analyze indoor air. If you want to know what's in your air, or you've had a leak or visible growth, start with an independent state-licensed professional.

What to do next

1. Put a hygrometer in your main living area and watch it for a week.
2. Set the thermostat fan to "Auto" and run bath and kitchen fans every time.
3. If readings stay above 50%, have Gold Eagle Services check your AC and talk through a whole-home dehumidifier.
4. Once humidity stays at 50% or below, if the house still smells stale, call Pure Maintenance Austin about a whole-home dry fog treatment.

Get a free phone consultation

Pure Maintenance Austin, brought to you by Gold Eagle Services, serves all of Central Texas, including College Station, Round Rock, Georgetown, San Marcos, Bastrop and Marble Falls. Book a free phone consultation: a Comfort Advisor calls you, learns what's going on in your home and sends a written quote based on square footage. Call 512-904-4646 or email IAQ@goldeagleservices.com.