How Subterranean Termites Get Into Structures

A Guide for Architects and Builders

Dina Richman

University of Florida

How Does the Problem Start?

A. Existing Colony– Tubes connect colony to structure– Most frequently near moist wood and soil

B. New Colony– King and queen choose area and excavate– Seek moist wood and soil

• Require Food, Water, and Access

Existing Colony: Mud Tubes Connect Colony in Soil with Wood in House

Typical Termite Entry Into Structures

1. Termites consume wood in ground

3. Finally infest wood2. Then construct tunnels

Mud Tubes

Wood Next to or Under Structure

Provides Food

Termites Access Into StructureFloating Slab

Termites Access Into StructurePartially Supported Slab

Termites Access Into Structure Supported Slab With Veneer

Termites Access Into StructureMonolithic Slab With Veneer

Crack in foundation

Wood in contact with soil

Termites Access Into StructureWooden Porch

Termites Access Into StructureDirt-Filled Porch

Foundation Penetrations

Concrete shrinkage allows termites access

Foraging and Guidelines

• Guidelines preferred

• When unconstrained, termites will tunnel in a radiating pattern

• When guidelines are introduced, the uniform tunneling pattern is disrupted and direction proceeds along guidelines

Foraging and Guidelines

Day 14 Day 14 (Found Gap 3d)

What Are Guidelines?

Construction Mistakes and Homeowner Alterations Allow

Termite Access

Exterior Finish Below Grade

Allows Termites Hidden Access

Hidden Termite Access

• Monolithic slab

• Vapor barrier used as form

• Brick veneer and stucco extending below ground

Hidden Termite Access

Subterranean Termite Entry Points

• Foundation– Cracks– Plumbing connections– Expansion joints– Utility conduits– Non-integral footers

(Cold joints)

•Exterior Siding–Stucco–Brick veneer–Wood, vinyl,

Hardy Board–EIFS

New Colony: What Makes an Area Attractive?

Moisture Next to Foundation

• Gutters and downspouts

• Improper drainage, grading

• Sprinklers, irrigation, water spigots

• Roof leaks

Gutters

• New Building Code– Gutters and down

spouts on eaves under 6” wide

Water can build-up next to foundation due to lack of gutters

Mis-directed downspouts

Sprinkler head directs water towards bushes

Roof

gravity

Improper Roof Flashing

No flashing

Not effective•Allows moisture buildup

•In wall voids•Adjacent to foundation

Walls Voids

Summary of Key Concepts• Food

– Wood-to-soil contact

– Form boards not removed

– Wooden debris left inside CMUs

– Wood refuse buried under slab

• Water– Improper drainage, grading

– Irrigation wets foundation

• Access– Exterior cladding, EIFS below grade

– Landscaping

– Plumbing penetrations

– Additions, adjacent slabs

Why Pre-Construction Treatments Fail

• Pre-construction disruption– Additional grading, vapor barrier, walking across treated area

• Contractor error– Grade stakes, form boards, cellulose debris within foundation

• Post-construction disruption– Landscaping or add-ons

• Breakdown due to climate and soil conditions• Applicator error

Infestation Rates in St. John’s County

27

6.7

0

5

10

15

20

25

30

Old Code Termite Code

Perc

ent I

nfes

ted

X2 = 120.533, df = 2, P = 0.001

Author: Dina Richman, University of Floridadlri@gnv.ifas.ufl.edu

Photos: Dina Richman and Cynthia Tucker, University of Florida

Entomology And Nematology Department Copyright University of Florida 2000

For more detailed information see the Featured Creatures WWW site at

http://creatures.ifas.ufl.edu/