Moisture Control for Termite Prevention

How Moisture Attracts Termites

• Subterranean termites: Must maintain contact with moisture source (soil or water)
• Softens wood: Moist wood is easier to chew and digest
• Fungal decay: Moisture causes rot, making wood more attractive
• Colony survival: Termites die without adequate moisture
• Increased activity: Wet conditions accelerate feeding and reproduction

Common Moisture Problems

• Poor drainage around foundation
• Clogged or damaged gutters
• Plumbing leaks (visible and hidden)
• Inadequate ventilation in crawl spaces/attics
• Condensation on pipes and ducts
• Improper grading
• Roof leaks
• High indoor humidity

1. Proper Grading and Drainage

Goal: Direct water away from foundation

Grading requirements:

• Slope away from foundation at minimum 6 inches over 10 feet
• Maintain slope for at least 10 feet from structure
• Fill low spots that collect water
• Regrade if settling has created reverse slopes

How to check:

• Walk perimeter after heavy rain
• Look for standing water or wet spots
• Check for water stains on foundation
• Note where water flows during rain

Solutions:

• Add soil to create proper slope
• Install swales to channel water
• Create drainage paths away from house
• Consider professional regrading for severe issues

Cost: DIY $100-500 for soil; professional $1,000-5,000

2. Gutter and Downspout Management

Why critical: Roof water concentrated at foundation causes major moisture problems

Gutter maintenance:

• Clean gutters twice yearly (spring and fall)
• Remove leaves, debris, and nests
• Check for proper pitch (1/4 inch per 10 feet toward downspouts)
• Repair sagging sections
• Seal leaks at seams and end caps
• Consider gutter guards in wooded areas

Downspout requirements:

• Extend at least 4-6 feet from foundation
• Use splash blocks or extensions
• Direct water toward drainage areas
• Never discharge onto walkways or toward house
• Consider underground drainage for better aesthetics

Signs of problems:

• Water overflowing gutters during rain
• Staining on siding below gutters
• Erosion at foundation
• Wet basement or crawl space
• Ice dams in winter

Cost: Cleaning $100-300; repairs $200-1,000; new gutters $4-30 per linear foot

3. French Drains and Drainage Systems

When needed: Persistent wet areas, high water table, poor natural drainage

Types:

• Surface French drain: Shallow trench with gravel and perforated pipe
• Deep French drain: Around foundation footer for basement waterproofing
• Curtain drain: Intercepts water upslope from house
• Dry well: Collects and disperses water underground

Installation:

• Trench sloped 1% toward outlet
• Landscape fabric to prevent clogging
• Perforated pipe (holes down)
• Gravel backfill
• Outlet to drainage area or storm sewer

Cost: $20-50 per linear foot installed

4. Roof and Flashing Maintenance

Inspection points:

• Missing or damaged shingles
• Cracked or deteriorated flashing
• Damaged chimney caps or vents
• Clogged roof valleys
• Moss or algae growth (indicates moisture retention)

Action items:

• Annual roof inspection
• Repair leaks immediately
• Replace damaged flashing
• Keep roof clean of debris
• Trim overhanging branches

1. Plumbing Leak Detection and Repair

Common leak locations:

• Under sinks and around toilets
• Water heater connections
• Washing machine hoses
• Refrigerator ice maker lines
• Shower and tub surrounds
• Pipe joints in walls and ceilings

Detection methods:

• Visual: Water stains, mold, warped flooring
• Water meter test: Turn off all water, check if meter still moves
• Toilet test: Food coloring in tank (appears in bowl if leaking)
• Listen: Hissing or dripping sounds
• Professional: Thermal imaging or acoustic detection

Immediate repairs:

• Replace worn washers and seals
• Tighten loose connections
• Replace damaged supply lines
• Re-caulk tubs and showers
• Fix running toilets

Cost: Minor repairs $50-200; major leaks $200-2,000+

2. Humidity Control

Target levels: 30-50% relative humidity (40-45% ideal)

Measurement:

• Use hygrometer ($10-30)
• Check multiple locations
• Monitor seasonally (humidity varies)

Reduction strategies:

• Dehumidifiers: In basements and damp areas (30-70 pint capacity)
• Exhaust fans: In bathrooms and kitchen (vent to exterior)
• Air conditioning: Removes moisture while cooling
• Ventilation: Open windows when outdoor humidity is lower
• Limit moisture sources: Cover pots while cooking, shorter showers

High humidity signs:

• Condensation on windows
• Musty odors
• Mold or mildew growth
• Warped wood or peeling paint

Cost: Dehumidifiers $150-400; exhaust fans $100-500 installed

3. Condensation Prevention

Common condensation areas:

• Cold water pipes
• Air conditioning ducts
• Windows in winter
• Toilet tanks
• Basement walls and floors

Solutions:

• Pipe insulation: Foam sleeves on cold water pipes
• Duct insulation: Wrap AC ducts in unconditioned spaces
• Window treatments: Storm windows, insulated curtains
• Toilet tank insulation: Foam liner or insulated tank
• Vapor barriers: On basement walls (if appropriate)

Ventilation vs. Encapsulation

Traditional ventilation:

• 1 sq ft vent per 150 sq ft floor area (with vapor barrier)
• Cross-ventilation for air flow
• Screens to keep pests out
• Works in dry climates

Encapsulation (modern approach):

• Seal vents and cover walls/floor with vapor barrier
• Condition space with HVAC or dehumidifier
• Better moisture control in humid climates
• Reduces energy costs
• More expensive but more effective

Cost: Ventilation improvements $200-1,000; encapsulation $5,000-15,000

Vapor Barriers

Purpose: Prevent ground moisture from entering crawl space

Installation:

• Use 6-mil or thicker polyethylene
• Cover entire floor area
• Overlap seams 12 inches, tape
• Extend 6 inches up walls
• Seal around piers and penetrations

Maintenance:

• Inspect annually for tears or gaps
• Repair damage promptly
• Ensure proper overlap at seams
• Replace if deteriorated

Cost: DIY $0.10-0.50 per sq ft; professional $1-3 per sq ft

Drainage and Sump Pumps

When needed: Standing water, high water table, persistent dampness

Solutions:

• Interior perimeter drain: Around crawl space perimeter to sump
• Sump pump: Removes collected water
• Battery backup: Ensures operation during power outages
• Discharge line: Extends well away from foundation

Cost: Sump pump $500-2,000 installed; drainage system $2,000-10,000

Ventilation Requirements

Standard: 1 sq ft vent per 150 sq ft attic floor (or 1:300 with vapor barrier)

Ventilation types:

• Ridge vents: Continuous vent along roof peak
• Soffit vents: Intake vents under eaves
• Gable vents: Vents in gable ends
• Power vents: Thermostat-controlled fans

Balanced system:

• Equal intake (soffit) and exhaust (ridge/gable) area
• Unobstructed air flow
• Insulation baffles to maintain air channels

Preventing Moisture Entry

• Bathroom exhaust: Vent to exterior, not attic
• Kitchen exhaust: Vent to exterior
• Seal penetrations: Around pipes, wires, chimneys
• Insulation: Proper R-value with vapor barrier facing down
• Roof leaks: Repair immediately

Spring

• Clean gutters after winter
• Check grading after snow melt
• Inspect for roof damage
• Test sump pump
• Check crawl space for standing water

Summer

• Run dehumidifiers in humid climates
• Monitor AC condensate drainage
• Check for plumbing leaks
• Ensure proper attic ventilation
• Trim vegetation for air flow

Fall

• Clean gutters before winter
• Extend downspouts
• Seal exterior cracks
• Check crawl space vents
• Prepare drainage systems for winter

Winter

• Prevent ice dams (insulation, ventilation)
• Monitor indoor humidity
• Check for condensation on windows/pipes
• Insulate exposed pipes
• Address any roof leaks immediately