7B Ch4 Cheat Sheet: Soil Treatment for Subterranean Termites

🎯 Top 5 Traps

1

Floating slab is the MOST susceptible — not monolithic. The expansion joint between foundation wall and slab floor is a primary entry point. Monolithic (one continuous concrete pour) has the fewest entry points. Suspended slab sits between.

2

Vertical drilling: max 12 inches apart, LOW pressure. Most common interior slab method. Wrong answers swap "high pressure" or "18 inches." Inject under low pressure so termiticide overlaps in the soil between holes.

3

Brick or stone veneer: drill ONLY where the brick ledge is below grade. Above-grade choices are distractors. Use 1/4 or 3/8 inch holes, every other brick, sealed after treatment. Never drill above the top of the foundation or interior slab.

4

Monolithic slab is THE EXCEPTION. Interior perimeter treatment may not be needed. No routine wood treatment. Trenching is the most practical exterior method — rodding has no advantage here.

5

Routine or annual retreatments: NEVER. Retreatments are made only on evidence of reinfestation, inadequate initial treatment, or a barrier broken by soil disturbance — and recorded as a partial or spot treatment.

🔢 Numbers You Must Know

Number

What It Represents

1/32 inch

Minimum foundation crack subterranean termites can enter through

4 to 12 inches

Spacing between rod insertions for soil rodding (varies by soil type)

12 inches

Maximum spacing for vertical drill holes through interior slab; also crack/expansion-joint drill spacing; also exterior abutting-slab drill spacing

less than 20 psi

Low-pressure spec for horizontal preconstruction barriers (coarse spray nozzle)

6 to 8 inches

Trench width along walls/piers in crawl spaces (interior and exterior)

1 foot

Maximum exterior crawl-space trench depth; also rough soil-removal level above the footing for trenching

1 inch / 1 foot apart

Diameter and spacing of crowbar/pipe/rod holes in trench bottom (used when land slopes or footing is more than 12 inches deep)

1/4 or 3/8 inch

Drill-hole size for brick or stone veneer voids

4 feet

Minimum preconstruction trench depth when foundation is deeper than 4 feet (treat as backfill is replaced, or to 4 ft after backfill)

0.5%

Standard emulsion concentration for subterranean termite control on the sample label

1 gal / 10 sq ft

Horizontal barrier rate at 0.5% emulsion

4 gal / 10 lin ft / ft depth

Vertical barrier rate at 0.5% emulsion (per foot of depth)

1.5 gal

Volume per drill hole for pipe/conduit penetrations 6 inches or less in diameter (0.5% emulsion)

3 gal / sq ft

Bath trap rate at 0.5% emulsion (per square foot of opening)

6 inches

Pipe/conduit diameter threshold for one drill hole; also distance from wall for basement floor-and-wall holes (6–8 inches, to clear footing)

🔀 Easily Confused

Pair / Group

Distinguishing Feature

Soil treating vs Foundation treating

Soil: termiticide applied to soil under and adjacent to building (continuous chemical barrier). Foundation: termiticide applied to the foundation itself — cracks at footing, cracks in foundation wall, hollow concrete block voids.

Floating vs Monolithic vs Suspended slab

Floating: foundation wall and footing separated from slab floor by expansion joint. Monolithic: foundation footing and slab floor formed as one continuous concrete unit. Suspended: slab floor extends over the top of the foundation wall.

Trenching vs Rodding

Trenching: remove soil to ~1 foot above footing, treat as soil is replaced. Rodding: inject termiticide through a long pipe at intervals (4 to 12 inches apart). Combination is common when footing is far below grade.

Short rodding vs Long rodding

Short: drill through foundation 12 inches apart, inject below the slab expansion joint from outside. Long: rod horizontally just below slab level under the slab — adds access behind concrete porches but may veer off, leaving untreated soil.

Vertical drilling vs Long rodding

Vertical drilling: most common interior method, holes through slab. Long rodding: similar advantages from exterior, but works only when bottom of interior slab is accessible.

Pre- vs Postconstruction

Preconstruction: it is illegal to use less than OR more than the label rate/concentration. Postconstruction: volume may be adjusted per the label's volume-adjustment chart (concentrations of 0.5%, 1.0%, or 2.0%).

Spot/Limited vs Full treatment

If exterior soil cannot be treated to the top of the footing, the work must be clearly labeled to the customer as a spot or limited treatment — and recorded as such on the statement of services.

🏠 Treatment by Foundation Type

Type

Core Treatment

Special Notes

Floating slab

Trench/rod exterior soil; drill beneath abutting exterior slabs; interior vertical drill, short rod, or long rod; drill and treat block voids

Expansion joint = primary entry. Most susceptible slab type. Block voids drilled close to outside grade, NOT above top of inside slab.

Monolithic slab

Trench exterior soil; drill brick/stone veneer voids only if they extend below grade

EXCEPTION: usually no interior perimeter treatment; no routine wood treatment. Trenching most practical — rodding has no advantage. Inspect bath traps, pipe penetrations, slab faults.

Suspended slab

Treated similarly to floating slab

Slab floor extends OVER top of foundation wall. Entry points include masonry above the wall and any cracks/openings in the slab.

Crawl space

Remove all cellulose debris first; trench 6–8 in wide on both sides of foundation/support walls and around piers

Don't trench below top of footing. If land slopes or footing is more than 12 in deep, add 1-inch / 1-ft-apart holes in trench bottom to footing.

Basement

Trench/rod exterior to greater depth than other types; treat at expansion joint between floor and wall; treat brick veneer voids if below grade

Holes 6–8 in from wall (to clear footing). Extreme caution with block/rubble/masonry walls behind finished interior walls — termiticide may seep into the structure.

📐 Postconstruction Application Rates

From the sample Termite-Icide label. Volume halves as concentration doubles.

Application

0.5% Rate

Higher Concentrations

Horizontal barrier

1 gal per 10 sq ft

0.5 gal at 1.0%; 0.25 gal at 2.0%

Vertical barrier

4 gal per 10 lin ft per ft of depth

2 gal at 1.0%; 1 gal at 2.0%

Cracks / expansion joints

4 gal per 10 linear feet

Drill 12-in spacing through slab on one side of crack

Pipe/conduit, 6 in or less

1.5 gal per drill hole

One drill hole through slab on one side

Pipe/conduit, over 6 in

1.5 gal per drill hole

Add one hole per each additional 6 in of diameter (or fraction)

Bath trap

3 gal per square foot of opening

Apply at 0.5% emulsion

💡 Memory Hooks

Slab susceptibility — "Float, Suspend, Mono": Floating most susceptible (expansion joint), Suspended next, Monolithic least. The fewer joints, the fewer entry points.

Vertical drilling — "12 and low": 12 inches max between holes, low pressure for soil overlap. Both halves matter.

Volume Adjustment — "Halve and double": Volume HALVES every time concentration DOUBLES. 0.5% to 1.0% halves the gallons; 1.0% to 2.0% halves them again.

Brick veneer rule — "Below or no": Drill brick veneer ONLY where ledge is below grade. Above grade = no drill.

Retreatment — "Evidence, not calendar": No annual or routine retreats. Retreat only when there's reinfestation, inadequate initial treatment, or a broken barrier.