Sticky summer air can sneak into your home, make rooms feel warmer than the thermostat reads, and even invite mold if you are not careful. If you live in Jacksonville or anywhere in East Texas, you know the feeling. The good news is you can keep interiors dry, comfortable, and efficient with the right mix of HVAC design, dehumidification, ventilation, and weather‑sealing. This guide breaks down what works in our hot‑humid climate and how to use it when you own, buy, or sell. Let’s dive in.
Why humidity is a big deal in Jacksonville
East Texas sits in a hot‑humid climate. Long, warm seasons and high dew points mean your cooling system has to pull moisture out of the air while it cools. If a system only chases temperature, indoor relative humidity can climb.
For a healthy home, keep indoor relative humidity below 60 percent at all times. Aim for roughly 40 to 50 percent in the cooling season when possible. Lower humidity helps you feel cooler at a higher thermostat setting, but aggressive drying costs energy, so you want balanced solutions that increase runtime and remove moisture without waste.
Right‑size your HVAC for humidity control
Start with a Manual J load calculation
Ask for a professional Manual J calculation any time you replace equipment or size a new system. Manual J captures both sensible load and latent load so the system matches your home’s real needs. Avoid rule‑of‑thumb tonnage based on square footage.
Avoid oversizing
Oversized units short cycle, which means the system cools the air fast but does not run long enough to wring out moisture. You may hit your setpoint but still feel clammy. Correct sizing based on Manual J, followed by Manual D for ducts and Manual S for equipment selection, gives you better comfort and better humidity control.
Choose equipment that manages moisture
- Variable‑speed or multi‑stage compressors run longer at lower speeds, improving moisture removal.
- Variable‑speed or ECM blower motors let your contractor tune airflow for better dehumidification and efficiency.
- Proper fan airflow matters. Target the right CFM per ton so the coil can remove moisture. Some systems use lower airflow during humid months to boost latent performance. This should be designed and documented, not a guess.
- Use matched components verified by AHRI or manufacturer data so the system performs as designed.
Ducts can make or break performance
Leaky or uninsulated ducts in a hot attic or vented crawlspace waste cooling and undermine humidity control. Whenever possible, locate ducts inside conditioned space. If ducts must be in the attic or crawlspace, seal with mastic or UL‑listed tape and insulate to the required R‑value. A duct leakage test can confirm performance and guide repairs.
Commissioning matters
On startup, your technician should verify refrigerant charge, airflow across the coil, and static pressure, and collect superheat and subcooling readings. These checks confirm the system is delivering design airflow and moisture removal. Use a thermostat that monitors humidity and supports dehumidification control.
Dehumidification that actually works
Whole‑house dehumidifier
A ducted whole‑house dehumidifier can maintain set humidity across the home, even when the AC is off or cycling lightly. It drains to plumbing, integrates with your thermostat, and can include reheat so you do not overcool while drying. Ensure a proper condensate drain and overflow protection.
AC‑integrated dehumidification modes
Many modern variable‑speed systems include dedicated dehumidification settings. They fine‑tune compressor and fan speeds to increase moisture removal. Some use reheat strategies so you stay comfortable while the system dries the air.
Room or portable dehumidifiers
Portable units can help in problem areas like a converted garage, bathroom, or basement‑like space. They do not replace whole‑house control. Plan for regular maintenance and safe drainage.
Smart controls and setpoints
Use a thermostat or controller with humidity monitoring. Set a humidity target and let the system maintain it. Consider schedules and setbacks to reduce run hours when not needed. Demand‑controlled ventilation tied to humidity can limit how much outdoor moisture you bring inside during the stickiest hours.
Ventilation without the moisture penalty
Use exhaust fans the right way
Bathroom and kitchen exhaust fans should vent outdoors, not into the attic. Run the bath fan during and after showers. A humidity‑sensing fan helps the space dry out without you having to remember a timer. A kitchen range hood vented outside removes cooking moisture at the source.
Whole‑house ventilation that fits our climate
In hot‑humid regions, Energy Recovery Ventilators often work better than HRVs because ERVs transfer some moisture from the incoming air stream to the outgoing exhaust, which reduces the moisture you introduce. No system cancels humidity entirely, so coordinate ventilation with your AC and dehumidification plan. Bringing fresh air into the HVAC return lets the coil condition and dehumidify it before it reaches living spaces.
Demand control for fewer sticky hours
Use CO2 or humidity sensors to supply fresh air only when needed. This reduces unnecessary moisture introduction during peak humidity.
Seal the envelope and stop moisture at the source
Air sealing priorities
Air leaks pull humid air indoors. Seal gaps at top plates, around windows and doors, and at plumbing and electrical penetrations. Treat recessed lights and attic access points. Improve attic insulation and air sealing to reduce heat load and improve AC runtime and moisture control.
Crawlspace encapsulation for East Texas homes
Vented crawlspaces invite damp air. Encapsulate the crawlspace with a continuous vapor barrier on the floor and walls, seal vents, and either condition the space or add a dehumidifier sized for that volume. This approach reduces ground moisture and improves indoor air quality.
Vapor retarders and drying
In hot‑humid climates, avoid interior Class I vapor barriers like polyethylene that can trap moisture. Use assemblies that can dry outward and choose smart vapor retarders where appropriate. Follow local codes and building‑science‑based details for your cladding and insulation.
Exterior drainage and quick fixes
Keep water away from the foundation with positive grading and working gutters and downspouts. Fix roof or plumbing leaks quickly. Ensure window and door flashing is in good condition.
Duct sealing and insulation recap
Even small duct leaks in attics can pull in hot, humid air and add moisture load. Seal with mastic, verify with a duct leakage test, and insulate to the recommended R‑value.
For buyers and sellers: what to test and negotiate
Smart tests that give you leverage
- Manual J load report and equipment selection documents for recent HVAC replacements
- Commissioning report with refrigerant charge, airflow, static pressure, and control verification
- Duct leakage test and a summary of duct locations
- Indoor humidity data log over several days to spot persistent RH above 60 percent
- Blower door test to measure overall air leakage on homes with major concerns
- Thermal imaging to catch cold spots and potential condensation issues
- Visual checks for water stains, mold, or efflorescence in attics, crawlspaces, bathrooms, and around windows
- Confirmation that bathroom and kitchen fans vent to the exterior
Repair items worth requesting
If testing shows problems, you can request or negotiate:
- Correct HVAC sizing or replacement, with Manual J/D/S documentation
- Whole‑house dehumidifier installation where RH remains high
- Duct sealing, insulation, or duct relocation into conditioned space, with a leakage test target
- Crawlspace encapsulation and a dehumidifier or conditioning plan
- Exterior drainage, gutter, and flashing corrections
- Proper exhaust fan venting to the exterior
- Licensed mold remediation if needed, with documentation
Homeowner maintenance habits
- Change HVAC filters on schedule and keep coils and access panels clean
- Schedule annual tune‑ups that include airflow and refrigerant checks
- Keep condensate drains clear and test condensate pumps
- Use kitchen and bath fans during moisture‑heavy activities
- Track indoor humidity with simple hygrometers in a few rooms
Next steps in Jacksonville
Start with the most cost‑effective fixes: air sealing, duct sealing, and drainage. Then confirm correct HVAC sizing and commissioning. Add integrated dehumidification and controlled ventilation if your RH still creeps up. Hire contractors who provide documentation, including Manual J/D/S, commissioning reports, and duct leakage results. Use this data to guide your improvements and to support negotiation when buying or selling.
If you want a local perspective on which fixes matter most for your home and budget, let’s talk about your goals, timeline, and next steps. Schedule a Free Consultation with [Unknown Company] to get tailored guidance for Jacksonville and Greater East Texas.
FAQs
What indoor humidity is best for Jacksonville homes?
- Keep indoor RH below 60 percent at all times and aim for 40 to 50 percent during the cooling season for comfort and mold prevention.
How do I know if my AC is oversized and causing humidity issues?
- Signs include short run times, rapid temperature swings, and clammy air. A Manual J load calculation and commissioning checks can confirm proper sizing and airflow.
Are ERVs worth it in hot‑humid East Texas?
- ERVs can reduce added moisture compared to simple supply ventilation by transferring some humidity between air streams. They work best when integrated with your AC and dehumidification plan.
Do I need a whole‑house dehumidifier or will portable units do?
- Portable units help in single rooms but do not control whole‑home moisture. A ducted whole‑house dehumidifier provides consistent results and integrates with your HVAC and drains.
What should buyers include in offers to address humidity control?
- Request documentation like Manual J, commissioning reports, duct leakage tests, and humidity logs. Negotiate repairs such as duct sealing, whole‑house dehumidifier installation, or crawlspace encapsulation if results show issues.
How does crawlspace encapsulation help in East Texas?
- It blocks ground moisture and humid outdoor air from entering, which lowers indoor humidity and supports better comfort, air quality, and system performance.
