Termite Damage Pattern Reference Guide

Foundation and Substructure

Sill plates and rim joists:

• Appearance: Hollowed wood along grain, may appear intact from outside
• Indicators: Soft or spongy when probed, sounds hollow when tapped
• Severity: High—these are critical structural components
• Common cause: Subterranean termites from soil contact
• Associated signs: Mud tubes on foundation nearby

Floor joists:

• Appearance: Galleries along grain, weakened cross-section
• Indicators: Sagging floors above, visible damage in crawl space
• Severity: High if multiple joists affected
• Pattern: Often starts at ends near foundation
• Risk: Can lead to floor collapse if extensive

Support posts and piers:

• Appearance: Damage from ground level upward
• Indicators: Visible galleries, mud tubes, soft wood
• Severity: Very high—supports entire structure
• Pattern: Concentrated at soil contact point
• Action: Immediate professional assessment needed

Wall Framing

Wall studs:

• Appearance: Hollowed interior, thin shell remaining
• Indicators: Bulging drywall, cracks, nail pops
• Severity: Moderate to high depending on load-bearing status
• Detection: Often hidden until drywall removed
• Pattern: May follow plumbing or moisture sources

Bottom plates:

• Appearance: Extensive hollowing along length
• Indicators: Baseboards pulling away, floor gaps
• Severity: Moderate—distributes wall load
• Common in: Exterior walls, bathrooms, kitchens
• Access: Visible from crawl space or when baseboard removed

Headers and lintels:

• Appearance: Galleries in load-bearing beam over openings
• Indicators: Sagging doors/windows, cracks above openings
• Severity: High—supports wall above opening
• Risk: Can cause significant structural failure
• Urgency: Requires immediate attention

Doors and Windows

Door frames:

• Appearance: Hollowed jambs, soft spots
• Indicators: Door won't close properly, gaps, soft when pressed
• Severity: Low to moderate (usually not structural)
• Pattern: Often at bottom of frame near floor
• Repair: Frame replacement typically sufficient

Window frames and sills:

• Appearance: Hollowed sills, damaged frames
• Indicators: Soft wood, paint bubbling, difficult to open
• Severity: Low (cosmetic/functional issue)
• Common cause: Moisture + drywood termites
• Prevention: Keep caulking intact, fix leaks

Attic and Roof Structure

Rafters and trusses:

• Appearance: Galleries in roof support members
• Indicators: Sagging roof line, visible damage from attic
• Severity: Very high—roof structural integrity
• Species: Often drywood termites in warm climates
• Risk: Roof collapse possible if extensive

Fascia and soffit:

• Appearance: Hollowed boards, visible galleries
• Indicators: Soft spots, paint damage, visible holes
• Severity: Low (not structural but allows water entry)
• Secondary risk: Water damage can worsen termite problem
• Repair: Board replacement usually sufficient

Subterranean Termite Damage

Characteristic patterns:

• Direction: Follows wood grain (eat softer spring wood)
• Galleries: Packed with soil and mud
• Appearance: Layered, honeycomb pattern
• Moisture: Often damp or water-stained
• Location: Starts near ground, moves upward

What you'll see:

• Mud tubes connecting soil to wood
• Soil-filled galleries
• Damage concentrated at soil contact points
• Progressive damage from ground up
• Associated moisture problems

Drywood Termite Damage

Characteristic patterns:

• Direction: Cuts across grain
• Galleries: Clean, smooth walls
• Appearance: Chambers connected by tunnels
• Frass: Pellet piles below kick-out holes
• Location: Can be anywhere (not limited to ground level)

What you'll see:

• Small kick-out holes (1-2mm)
• Piles of hexagonal pellets
• Clean galleries without mud
• Damage in attics, furniture, trim
• No mud tubes

Dampwood Termite Damage

Characteristic patterns:

• Direction: Follows grain
• Galleries: Large, smooth chambers
• Appearance: Clean but may contain fecal pellets
• Moisture: Always in very wet wood
• Location: Roof leaks, plumbing leaks, ground contact

What you'll see:

• Damage only in moisture-damaged wood
• Large galleries
• Often accompanied by fungal decay
• Fecal pellets stuck together (moisture)
• No mud tubes

🚨 Critical (Immediate Action Required)

• Damage to load-bearing members (posts, beams, headers)
• Multiple floor joists compromised
• Roof structure affected
• Foundation sill plates extensively damaged
• Visible sagging or structural deformation
• Active infestation in structural components

Action: Immediate professional structural assessment and treatment

⚠️ Moderate (Prompt Attention Needed)

• Single joist or stud damaged
• Non-load-bearing wall framing affected
• Door or window frames compromised
• Fascia or trim damage
• Localized damage with active infestation
• Previous damage with no current activity

Action: Schedule inspection and treatment within weeks

✓ Minor (Monitor and Repair)

• Cosmetic damage only
• Old damage, no current activity
• Non-structural trim or molding
• Small areas of surface damage
• Furniture damage (not structure)

Action: Repair as convenient, maintain prevention measures

Termite Damage vs. Carpenter Ant Damage

Termite damage:

• Galleries follow grain (subterranean) or cross grain (drywood)
• Packed with mud (subterranean) or clean (drywood)
• Wood consumed for food
• Frass is pellets (drywood) or mud (subterranean)
• Galleries relatively smooth

Carpenter ant damage:

• Galleries smooth and clean
• Wood excavated, not eaten
• Frass is sawdust-like with insect parts
• Galleries have "sandpapered" appearance
• Usually in already-damaged wood

Termite Damage vs. Wood Rot

Termite damage:

• Distinct galleries or tunnels
• Thin shell may remain intact
• Damage progresses from specific entry point
• Associated with termite signs (tubes, frass, swarmers)
• Wood structure hollowed but maintains some integrity

Wood rot (fungal decay):

• Wood breaks into cubes or crumbles
• Discoloration (brown, white, or black)
• Musty odor
• Wood becomes soft and spongy throughout
• Always associated with moisture
• No galleries or tunnels

Note: Termites and rot often occur together (both attracted to moisture)

Termite Damage vs. Powder Post Beetles

Termite damage:

• Galleries relatively large
• Frass is pellets (drywood) or mud (subterranean)
• Exit holes 1-2mm (drywood)
• Damage can be extensive quickly

Powder post beetle damage:

• Tiny exit holes (1-2mm, round and clean)
• Fine, flour-like powder (frass)
• Galleries very small and numerous
• Damage progresses slowly
• Often in hardwood flooring or furniture

What to Document

• Location: Specific room, component, and position
• Extent: Dimensions of affected area
• Appearance: Describe galleries, frass, mud tubes
• Severity: Structural vs. cosmetic
• Associated signs: Moisture, tubes, swarmers
• Date discovered: When you first noticed

How to Document (for Professional)

• Take photos from multiple angles
• Include reference object for scale
• Photograph overall area and close-ups
• Note measurements if possible
• Document all affected areas
• Don't disturb damage (inspector needs to see it)

Cosmetic Repairs

• Trim and molding replacement
• Drywall patching
• Paint and finish work
• Non-structural wood replacement

Cost: $100-1,000 typically

Structural Repairs

• Joist sistering or replacement
• Beam reinforcement or replacement
• Sill plate replacement
• Foundation repairs
• Roof structure repairs

Cost: $1,000-20,000+ depending on extent

Note: Requires licensed contractor, often needs permits