Module 4 — House Wash: Diagnose Before You Spray (Lesson)
House washing is where most operators earn their reputation — good or bad.
The work itself is simple. The diagnosis is not. This lesson teaches you to slow down for 90 seconds and identify what you’re looking at so you don’t turn oxidation, bad paint, or pre-existing damage into a callback.
What you’re doing today
Before you spray anything, you’re going to identify what you’re actually looking at.
A clean house wash is simple. A bad diagnosis is expensive.
Why this matters
The biggest money-loser in house washing is treating oxidation like mildew.
Soft wash is about results with control: low pressure + the right chemistry + dwell + a gentle rinse. Pressure is a tool — but on the wrong surface it’s a damage multiplier.
That mistake creates:
- disappointed customers
- “it didn’t work” reviews
- callbacks that eat your week
Tools & materials (minimum viable)
- Phone camera (Proof Pack)
- Gloves + eye protection (minimum)
- Water source + hose
- Soft wash application method (DS / 12V / whatever you run)
Optional but recommended:
- microfiber rag (for oxidation test)
Quick diagnosis (3 buckets)
A) Organic growth (algae/mildew)
Usually looks like:
- green/black film
- patchy growth in shaded or damp areas
This is a standard soft wash workflow.
B) Oxidation (chalky paint)
Usually looks like:
- chalky residue
- color transfer when rubbed
- the surface looks "dirty" but it’s actually the coating failing
This is not a normal wash problem.
You must set expectations and decide whether you offer restoration.
C) Specialty stains / damage
Examples:
- rust stains
- hard-water staining
- irrigation stains
- pre-existing damage
These may require specialty treatment or a scope exclusion.
Step-by-step: the 2-minute diagnosis routine
- Walk the home once. Don’t touch chemicals yet.
- Pick 2–3 test spots: front + shaded side + worst area.
- Photo everything (Proof Pack pre-condition).
- Oxidation check (inconspicuous): wipe/rub lightly.
- If color/chalk transfers → oxidation risk.
- Decide your lane:
- organic → proceed with wash
- oxidation → expectation script + separate work (or exclude)
- specialty stain → spot plan (or exclude)
Decision points (foreman rules)
-
If you suspect oxidation and you’re not selling oxidation removal today:
- Do not promise restoration.
- Sell “clean and improved” with clear exceptions.
-
If you can’t confidently identify the stain:
- Stop. Test. Or exclude.
Common mistakes + fixes
- Mistake: "It’s all mildew." → Fix: do the wipe test.
- Mistake: promise results before testing → Fix: set expectations first.
What good looks like
- You can explain to the customer what you found in one sentence.
- You have before photos of the worst areas.
- You know whether it’s wash / restore / exclude.
How to prove it (Proof Pack)
Minimum photos:
- front elevation wide
- worst wall close-up
- test spot close-up
Add a note:
- "Organic vs oxidation: ____"
Do this next (assignment)
- Walk a home (real or mock) and classify each side: organic / oxidation / specialty.
- Write 2 sentences of expectation language for oxidation risk.
References (SOPs + checklists)
- Operator SOP: 04_sops/houses/house-wash-softwash-sop-v2.md
- QA checklist: 04_sops/houses/house-wash-qa-checklist-v1.md
- Homeowner explainer: 04_sops/houses/house-wash-homeowner-explainer-v1.md
- Proof Pack SOP: 04_sops/proof-pack/proof-pack-sop-v1.md
- Final Walk checklist: 04_sops/universal/final-walk-checklist-v1.md
Printables
- Operator Checklist Pack (truck copy): 03_curriculum/printables/operator-checklist-pack-v1.md
Field Guide & Interactive Calculator (tbsoftwash.com)
🏡 Interactive Stucco Paint Warranty, Siding Oxidation & Lanai Calculators:
Gear Box (Amazon)
House Wash Downstream, Pool Cage & Rinse Control Kit
- General Pump 100776 High-Draw Fixed Downstream Injector — reliable 10:1 house-wash draw without delicate moving parts.
- Jariko 4-Way J-Rod Nozzle Holder (4 GPM) + X-Jet DS Twist Adjustable Soft Wash Nozzle — instant transitions from 2-story soap reach to wide fan rinse.
- MTM Hydro DN10 Italian Ball Valve + Raincovo 3/8" Stainless Quick Connects.
- General Pump RB35 Low-Pressure Wash Down Gun — high-volume delicate rinsing around oxidized siding, lanai screens, and plants.
- YAMATIC Non-Marking 3/8" Pressure Washer Hose / Uberflex Pressure Washer Hose.
- 3M 12ft x 400ft Painter's Plastic — masking exterior outlets, keypads, and stained wood doors.
Disclosure: As an Amazon Associate, we earn from qualifying purchases.
🛡️ Module 4 Safety Gate — House Washing & Oxidation Diagnosis
Pass this quick operator knowledge check (80%+) to verify SOP mastery and unlock your track certification.