Is Your House Making You Sick? How to Spot and Fix a “Sick Home”

I came down with the flu and went down a rabbit hole on “sick building syndrome.” While my diagnosis was just the flu, a lot of homes really do make people feel lousy. If you’re buying, you don’t want to inherit one. If you’re selling, you don’t want to pass one along. And if you’re staying put, let’s make the place healthier.

Quick signs your home may be the problem

• Headaches, irritated eyes/throat, fatigue that improves when you’re away

• Musty or chemical smells that linger

• Visible moisture, staining, or mold

• Frequent “HVAC colds” after running the system

• Pets or pests you can smell before you see

The biggest culprits and fast fixes

1) Tight, low-ventilation homes

Newer or sealed buildings can trap pollutants.

Do now: Open windows daily when weather allows. Run bath and kitchen exhausts 20–30 minutes after use. If you live in a very tight building, ask an HVAC pro about an ERV/HRV (air exchanger).

2) Building materials and VOCs

Possible sources: asbestos or lead in older homes, and in any era, VOCs from finishes (formaldehyde, solvents), drywall dust, silica.

Do now: Increase fresh air, use low- or zero-VOC paints/finishes, and leave new furniture or flooring to off-gas with windows open. Test for asbestos/lead before disturbing old finishes.

3) Biology: mold, dust mites, pet dander, bacteria

Moisture + time = growth. High-humidity regions are most at risk.

Targets: Keep indoor humidity about 35–40%. Replace clogged filters, clean registers, wash or replace heavy draperies, deep-clean carpets or replace with hard surfaces if they’re holding odors. Consider a dehumidifier.

4) Humidifier “fever”

Contaminated humidifiers can aerosolize microbes and cause flu-like symptoms.

Do now: Clean per manual (often weekly), use distilled water, and monitor humidity so you’re not over-humidifying.

5) Radon

Colorless, odorless gas from soil that can enter through slabs or crawlspaces.

Do now: Radon test kit first. If elevated, common fix is an active sub-slab depressurization system (a fan and vent that pulls gas from under the slab).

6) Mold from leaks or previous “quick flips”

Paint over problems is still a problem.

Do now: Moisture and air sampling by a qualified inspector, plus a visual inspection with a thermal camera. Track down and fix the water source before remediation.

7) Sewer line and sewer gas

Root intrusion or breaks can cause backups and odors.

Do now: Schedule a sewer camera inspection, especially in older neighborhoods or homes with many trees. Cleanouts and routine maintenance are cheaper than emergencies.

8) Termites and wood pests

Swarmers shed wings in warm weather and can leave eggs in wood.

Do now: Annual or biannual inspections. If you see widespread activity, full-structure treatment may be required. Spot treatments won’t reach eggs hidden in framing.

9) Rodents and roaches

They spread allergens and disease, and the cleanup can be costly if ignored.

Do now: Seal entry points, set traps or call a pro early, sanitize affected attic/duct insulation if contaminated. In multi-unit buildings, ask about building-wide treatment history.

Buyer checklist (protect yourself)

• Order an indoor air quality assessment (mold, VOCs, particulates) if anything smells off or the home is very tight.

• Request a radon test and sewer scope during inspections.

• In condos or high-rises: ask about make-up air/ventilation design and filter change schedules.

• Open cabinets, look under sinks, check closets and window corners for moisture staining. Visit at two different times of day if possible.

Seller checklist (avoid surprises)

• Pre-list basics: HVAC service, new filters, dehumidify to 35–40%, deep clean soft goods, fix known leaks, clear any musty areas.

• If you’ve had pests, moisture, or prior remediation, gather invoices and warranties. Buyers relax when they see proof of professional work.

• Replace or remove heavily scented plug-ins and candles. Fresh and neutral reads healthiest to most buyers.

When to call a pro

• Persistent musty smell you can’t locate

• Visible mold larger than a dinner plate

• Recurrent leaks or attic condensation

• Radon levels above your state’s action level

• Rodent droppings in attic or duct runs

• Sewer backups or frequent slow drains

Simple gear that helps

• Indoor air quality monitor (tracks humidity and particulates)

• Dehumidifier (for damp climates or basements)

• High-MERV HVAC filters appropriate for your system

• Hygrometer for quick humidity checks in bathrooms and closets