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

By Mold Compass Editorial Team

As summer winds down, many vacation homeowners face the annual task of closing up for the season. What you do now determines what you'll find next spring. Properties left improperly closed can develop serious mold problems during months of vacancy—turning your escape into a nightmare.

Follow this comprehensive guide to close your summer home properly and prevent mold from taking hold during the off-season.

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
  • Months of ideal mold growing conditions

Before You Begin Closing

Inspection

Walk through checking for existing problems:

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

Address problems now—they'll be much worse by spring.

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

The safest approach—but most expensive:

  • Keep HVAC running at moderate setting (55-65°F heat, 78-80°F AC)
  • Set dehumidifier to 40-50%
  • Requires someone to check periodically
  • Best for properties with history of moisture issues

Option 2: Partial Climate Control

A balance of cost and protection:

  • Keep heat low enough to prevent pipe freeze (55°F)
  • Run dehumidifier on timer or continuous
  • Connect dehumidifier to floor drain
  • Have caretaker check monthly

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 water main
  • Drain hot water heater
  • Open all faucets
  • Flush toilets; add RV antifreeze to bowls and tanks
  • Pour antifreeze in all drains
  • Disconnect and drain washing machine
  • Drain outdoor faucets

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

Proper closing takes time and effort, but it's worth it. When you arrive next spring, you want to find a property ready to enjoy—not a mold remediation project. Invest the time now, and your future self will thank you.

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