Crack and Crevice Treatment: Mastering the Most Important Application Method

Crack and crevice treatment is the backbone of professional pest control, yet technicians, even experienced ones, often apply products in ways that violate labels, waste material, and deliver poor results.

Mastering this technique is what separates adequate pest control from excellent pest control.

What crack and crevice actually means

The EPA definition is specific: crack and crevice treatment means application into cracks and crevices where pests hide or live. The treatment targets harborage areas, not exposed surfaces.¹

Cracks: Non-porous surfaces that come together (where baseboard meets wall, where cabinet meets counter)

Crevices: Void spaces like wall voids, spaces between equipment and walls, hollow legs of furniture

This is not broadcast spraying. This is not spraying baseboards from 2 feet away with spray landing on floors and walls. This is targeted application into the actual openings where pests harbor.

Why this method works

Pests, particularly cockroaches, ants, and bed bugs, spend 75-90% of their time in harborage areas, not out on exposed surfaces. German cockroaches, for example, prefer to live in cracks and crevices within 10 feet of food and water.²

When you treat harborage areas directly, you:

1. Deliver pesticide where pests actually are
2. Minimize exposure to humans and pets (product is hidden in cracks)
3. Provide longer residual (product isn't walked on or cleaned away)
4. Use less product overall
5. Remain compliant with IPM principles and many facility requirements

The equipment that makes the difference

Tip selection

The right tip changes everything. For crack and crevice work, the recommended options include:

Pin-stream tips: Creates pencil-thin stream perfect for injecting into tight cracks. This is the primary tip for crack and crevice work. Allows precision and prevents overapplication.

Crack and crevice straw attachment: 6-12 inch rigid or flexible tube that extends reach behind appliances and into tight spaces. Essential for getting behind refrigerators and stoves without moving them.

Fan spray tip: Only for very shallow crevices where pin-stream would overshoot. Still targeting cracks, just using wider pattern for efficiency.

What NOT to use: Standard cone spray tips from 12+ inches away. That's broadcast spraying, not crack and crevice, regardless of what you tell the customer.

Application equipment

Compressed air sprayer (B&G, Chapin): Provides consistent pressure for precise application. 1-2 gallon models are ideal for residential work. Maintain pressure at 30-40 PSI for crack and crevice work, higher pressure causes excessive application and product waste.

Hand pump sprayer: Acceptable for small jobs but pressure decreases between pumps, affecting application consistency.

Aerosol with crack and crevice tip: Excellent for spot treatments and reaching difficult areas. More expensive per application but valuable for precision work.

Application technique

Pressure and flow rate

This is where most technicians go wrong. Crack and crevice treatment requires low flow rate and consistent pressure.

Correct: Trigger pulled partially to create steady thin stream. 5-10 seconds per linear foot of crack, moving tip steadily along opening. You should see product entering crack, not flowing back out.

Incorrect: Trigger fully depressed, product spraying out under high pressure, visible wetness on surfaces around crack. This is overapplication and creates contamination issues.

Distance and angle

Distance: Tip should be 2-6 inches from crack opening, close enough to direct stream precisely but not so close you block your view.

Angle: 45-degree angle to crack opening allows product to flow into opening rather than bouncing off surface. For vertical cracks, angle slightly downward to help product flow into void.

Movement speed

Move tip steadily along crack length. Don't stop and pool product in one spot. Think of it like caulking, smooth, continuous movement.

Speed check: If you're leaving visible wetness or seeing product run out of cracks onto surfaces, you're moving too slowly or applying too much pressure.

Common target areas in residential treatments

Kitchen

• Where baseboard meets floor (entire perimeter)
• Cabinet hinges and screw holes
• Gaps where cabinets meet walls
• Space between stove and counters
• Under and behind dishwasher
• Plumbing penetrations under sink
• Drawer runners and joints
• Electrical outlet cover edges (remove cover, treat around box, not into box)

Bathroom

• Plumbing penetrations under sink
• Where baseboard meets floor
• Around toilet base where it meets floor
• Bathtub and shower drain surrounds
• Medicine cabinet mounting points

Living areas

• Baseboards (cracks where they meet floor and wall, not face of baseboard)
• Window and door frames (gaps between frame and wall)
• Behind pictures and wall hangings (bed bug harborage)
• Furniture joints (if treating for bed bugs)

What is NOT crack and crevice treatment

Common labeling violations include:

Spraying exposed baseboards: Unless you're using the crack where baseboard meets floor, this is surface spraying, not crack and crevice

Spraying under appliances: If you're spraying the floor and wall surfaces under the refrigerator, that's surface treatment. Crack and crevice would be the specific gaps and openings.

Perimeter spray: Walking around room spraying baseboards from several feet away is broadcast/surface treatment, period.

General void treatment: Pumping large volumes into wall voids isn't crack and crevice, that's void treatment (which some labels allow but requires different rate and application method).

Volume and coverage

How much is enough?

For liquid treatments: You should see slight moisture in the crack opening but product should not run out onto adjacent surfaces. If you see running or pooling, you've overapplied.

For typical German cockroach treatment in average kitchen: 0.5-1 gallon mixed solution for complete crack and crevice treatment of all harborage areas. If you're using 2-3 gallons in a single kitchen, you're either treating too much area or overapplying.

Product selection for crack and crevice

Not all products are labeled for crack and crevice, and those that are may have specific restrictions.

Read the label for:

• Is crack and crevice application allowed?
• What locations are permitted/prohibited?
• Are there specific restrictions for food areas?
• What's the maximum application rate?
• Are there surface type restrictions?

Common crack and crevice products:

• Non-repellent residuals (fipronil, indoxacarb formulations)
• Pyrethroid formulations labeled for crack and crevice
• Microencapsulated or suspension concentrate formulations
• IGR formulations for disrupting reproduction

Never for crack and crevice:

• Products only labeled for surface or broadcast application
• Anything not specifically labeled for structural pest control
• Products that prohibit indoor use

Explaining it to customers

Customers often don't understand why you're not "spraying everywhere." A recommended explanation:

"We're treating the cracks and crevices where cockroaches actually live, behind your appliances, in cabinet cracks, and in the gaps where baseboards meet the floor. This targets the pests in their harborage areas while minimizing exposure to you, your family, and your pets. This is the IPM approach that provides better long-term control with less pesticide."

Most customers appreciate this explanation, especially parents and pet owners.

Documentation

When you document crack and crevice treatments, be specific:

Good: "Applied [Product Name] EPA Reg# [number] as crack and crevice treatment to kitchen cabinet hinges, plumbing penetrations under sink, baseboards behind stove and refrigerator, and gaps where counters meet walls. Used 16 oz of finished spray solution."

Bad: "Treated kitchen for roaches"

Specific documentation protects you if questions arise about application method or product use.

Common mistakes and how to fix them

Mistake 1: Using too much pressure Fix: Partially engage trigger, reduce sprayer pressure to 30-40 PSI

Mistake 2: Treating from too far away Fix: Get close (2-6 inches), use extension tips if needed

Mistake 3: Moving too slowly Fix: Steady continuous movement, 5-10 seconds per linear foot

Mistake 4: Visible wetness on surfaces Fix: You're overapplying, reduce pressure and flow rate

Mistake 5: Not treating actual harborage areas Fix: Do thorough inspection first to locate where pests actually are

The quality control check

After treatment, inspect your work:

• Are there visible runs or drips on surfaces? (If yes, you overapplied)
• Can you see wet product on exposed surfaces? (If yes, you missed the crack and hit surfaces)
• Did you treat where pests were observed or where droppings were found? (If no, you missed key harborage areas)

Perfect crack and crevice technique means product goes INTO cracks and crevices, not ON adjacent surfaces.

Why this matters

Proper crack and crevice treatment is:

• More effective (treats where pests are)
• Safer (minimal exposure to people and pets)
• More economical (uses less product)
• Compliant with labels and regulations
• Consistent with IPM principles
• Less likely to cause customer complaints

Poor technique wastes product, creates exposure risks, violates labels, and delivers inferior results.

Experienced professionals can walk into a customer's home and tell within 60 seconds whether the previous technician understood crack and crevice treatment. The evidence is visible: overspray on baseboards, product residue on floors, broadcast coverage instead of targeted treatment.

Don't be that technician. Master this technique and your results will prove the value of precision over volume.

Disclaimer: Always consult current product labels, Safety Data Sheets (SDS), and manufacturer protocols as the authoritative source for product use, safety information, and application instructions. Product labels are the legal standard for application methods, rates, and locations. The information provided here is educational and should not replace product label directions or professional training.

References