Closing the Summer Home: Mold Prevention for the Off-Season

Before closing a seasonal property, make a climate- and building-specific plan for leaks, freeze protection, power, humidity, pests, and periodic checks. No checklist can guarantee an unchanged property while it is vacant.

Use the steps below as prompts, then confirm any winterization, insurance, utility, and caretaker requirements for the property.

The Off-Season Mold Risk

Vacant properties face unique challenges:

• No one to notice leaks or water intrusion
• No climate control (unless you pay to run it)
• Trapped humidity from summer
• Temperature swings causing condensation
• Pest intrusion creating moisture and damage
• A long period without observation can allow a leak, condensation, pest, or humidity problem to continue

Before You Begin Closing

Inspection

Walk through checking for existing problems:

• Any musty odors?
• Visible mold anywhere?
• Active leaks?
• Water damage?
• Pest issues?

Address active problems before leaving when safe, and record what remains unresolved instead of assuming it will worsen or disappear on a fixed schedule.

Repairs

• ✓Fix any roof issues
• ✓Repair loose or damaged siding
• ✓Seal around windows and doors
• ✓Fix plumbing leaks
• ✓Clear gutters and downspouts

Interior Preparation

Kitchen

• ✓Clean out refrigerator completely
• ✓Prop refrigerator door open (prevents mold inside)
• ✓Empty and clean garbage disposal
• ✓Clean all surfaces
• ✓Check under sink for any moisture issues

Bathrooms

• Clean bathrooms thoroughly—mold grows on soap residue
• Pour RV antifreeze in toilets and drains
• Leave toilet lids up for air circulation
• Prop shower door open
• Check caulk condition—repair if needed

Bedrooms

• Strip beds—wash or remove all bedding
• Leave closet doors open
• Don't leave anything against exterior walls
• Consider moisture absorbers in closets

All Rooms

• ✓Vacuum and clean thoroughly
• ✓Open all interior doors
• ✓Pull furniture away from walls
• ✓Remove anything valuable that could be damaged

Moisture Control Strategy

Option 1: Full Climate Control

One option is monitored climate control; compare its equipment limits, cost, power reliability, and response plan:

• Set temperature and humidity within the equipment, building, climate, insurer, and utility guidance; avoid a setting that creates freeze or condensation risk
• Use a dehumidifier only within its operating and drainage limits and respond to overflow, outage, or high-humidity alerts
• Requires someone to check periodically
• Best for properties with history of moisture issues

Option 2: Partial Climate Control

A balance of cost and protection:

• ✓Protect plumbing from freezing according to local winterization and insurance guidance
• ✓Use a dehumidifier only with a safe, monitored drainage plan
• ✓Arrange a trusted check-in for power, water, temperature, humidity, and visible damage

Option 3: No Climate Control

For properties winterized to allow this:

• ✓Drain all water systems
• ✓Open all interior doors
• ✓Use desiccant moisture absorbers
• ✓Accept higher mold risk
• ✓Thorough inspection when reopening

Water System Winterization

If turning off water for winter:

• ✓Turn off or isolate water only when the plumbing, heat, winterization, and insurance plan support it
• ✓Drain and winterize systems according to the property and equipment instructions
• ✓Record valves, drains, and restart steps for the person checking the property

Basement/Crawlspace

These areas need special attention:

• ✓Run dehumidifier continuously or use desiccant
• ✓Check sump pump before leaving
• ✓Ensure drainage is working
• ✓Store nothing directly on floor
• ✓Check for any water intrusion signs

Exterior Preparation

• ✓Clean and extend gutters
• ✓Clear all drains
• ✓Ensure proper grading away from foundation
• ✓Cover window wells
• ✓Remove any debris against house
• ✓Trim vegetation away from structure

Monitoring During Off-Season

Smart Home Options

• Humidity sensors that alert via app
• Water leak detectors
• Temperature monitors
• Video cameras for visual checks

Human Monitoring

• ✓Hire caretaker for monthly checks
• ✓Ask neighbor to watch property
• ✓Schedule professional inspections
• ✓Respond quickly to any alerts

Documentation

Before closing:

• ✓Photograph all rooms
• ✓Note any concerns
• ✓Record meter readings
• ✓Keep with property records

Create a Checklist

Make a written checklist specific to your property:

• Every step you need to take
• Order of operations
• Contact info for caretaker/neighbors
• Emergency contacts
• Review and update annually

See You Next Summer

A documented closing and check-in plan reduces avoidable moisture risk, but the property still needs an appropriate response plan for weather, equipment, and access.

Choose a Monitoring Plan

Decide who can enter, who can authorize repairs, and what alerts require a response. Give that person shutoff locations, equipment manuals, emergency contacts, and the current policy or lease requirements. Sensors can report temperature, water, or humidity, but they do not inspect hidden materials or replace a physical check.

Open the Property Carefully

When you return, check for active water, power loss, freeze damage, unusual odors, condensation, pests, and equipment failures before unpacking or restarting systems. Photograph conditions, stop water only when safe, and define the drying, repair, or professional scope before disturbing materials.

• ✓Keep stored goods elevated and away from damp floors
• ✓Do not use antifreeze or chemical treatments unless the system instructions and local requirements call for them
• ✓Inspect after major weather or an alert, not only on a calendar date
• ✓Keep unresolved access and moisture limitations in the closing record

Sources and Further Reading

For current moisture and mold guidance, see EPA's A Brief Guide to Mold, Moisture, and Your Home.

For related planning, see ourHumidity Control guide, After a Leak guide and Seasonal Prevention Plan.