Chemical Mix Ratio Cheat Sheet

Essential ratios for house washing, roof cleaning, concrete, and more

Last Updated: April 5, 2026

Mix ratios matter. Get it wrong and you waste money or damage property. This sheet is your reference — print it and keep it accessible so you don't guess on the job.

⚠️ Important: Always follow manufacturer recommendations first. These ratios are industry standards, but specific products may vary. When in doubt, start weak and strengthen if needed.

Quick Reference Tables

House Wash Mix Ratios

Job Type	Sodium Hypochlorite (SH)	Water	Final Mix Ratio	Best For
Light Cleaning	0.5 gal	9.5 gal	0.5%	Dusting, maintenance cleaning, light algae
Standard House Wash	1 gal	9 gal	1%	Most residential washing, mildew, algae
Heavy Growth	2 gal	8 gal	2%	Heavy algae, mold, neglected homes
Extreme Cases	3 gal	7 gal	3%	Severe growth (use caution!)

💡 Pro Tip: 1% works for most houses. Stronger doesn't equal better — you risk plant damage and overspray. Pre-wet plants, rinse well, and use a downstream injector for better control.

Roof Cleaning Mix Ratios

Roof Type	Sodium Hypochlorite (SH)	Water	Additives	Application Method
Asphalt Shingles (Standard)	2-3 gal	7-8 gal	Surfactant (roof soap)	Low pressure pump sprayer
Asphalt Shingles (Heavy Growth)	3-4 gal	6-7 gal	Surfactant + metal inhibitor	Low pressure pump sprayer
Tile/Metal Roofs	1-2 gal	8-9 gal	Surfactant (optional)	Low pressure pump sprayer
Cedar Shake	1-1.5 gal	8.5-9 gal	Surfactant (gentle formula)	Low pressure pump sprayer

💡 Pro Tip: Never pressure wash asphalt shingles. Use a pump sprayer applied from bottom up. Roof cleaning is chemistry and dwell time, not pressure. Protect plants — roof runoff kills them fast.

Concrete Cleaning Mix Ratios

Stain Type	Sodium Hypochlorite (SH)	Water	Additives	Technique
General Dirt/Grime	1 gal	9 gal	None or degreaser	Preclean, downstream, surface cleaner
Oil/Grease	0.5 gal	9.5 gal	Degreaser/sodium metasilicate	Apply degreaser first, dwell, SH mix
Rust Stains	None	N/A	Rust remover (oxalic acid)	Apply directly, dwell, rinse
Tire Marks	1-2 gal	8-9 gal	Degreaser	Hot water if available, surface cleaner
Leaf Stains/Tannins	2-3 gal	7-8 gal	None	Strong mix, extended dwell

💡 Pro Tip: Concrete cleaning is mostly technique. Pre-wet, apply chemical evenly, let it work (don't let it dry), then clean with a surface cleaner. Hot water transforms results when available.

Downstream Injector Ratios

Injector Ratio	To Achieve 0.5%	To Achieve 1%	To Achieve 2%	To Achieve 3%
10:1 (Most common)	1:20 mix (5%)	1:10 mix (10%)	1:5 mix (20%)	1:3.3 mix (30%)
8:1	1:16 mix (6.25%)	1:8 mix (12.5%)	1:4 mix (25%)	1:2.7 mix (37.5%)
6:1	1:12 mix (8.3%)	1:6 mix (16.7%)	1:3 mix (33%)	1:2 mix (50%)
5:1	1:10 mix (10%)	1:5 mix (20%)	1:2.5 mix (40%)	1:1.7 mix (60%)

💡 How This Works: Your injector pulls chemical at a fixed ratio. Mix stronger in your bucket to compensate. Example: with a 10:1 injector, mix at 10% to get 1% final strength after injection dilutes it.

Common Additives & Their Uses

Surfactants (Roof Soap)

Helps chemical cling to vertical surfaces, prevents runoff, improves cleaning. Essential for roof cleaning.

Typical Amount: 8-16 oz per 5 gallons

Metal Inhibitor

Protects flashing, gutters, and metal fixtures from oxidation during roof cleaning.

Typical Amount: As per product label

Degreasers/Sodium Metasilicate

Breaks down oil, grease, and food-based stains. Great for restaurants, driveways, patios.

Typical Amount: 8-16 oz per 5 gallons

Oxalic Acid

Removes rust stains, tannin stains from leaves, and mineral deposits. Harsh — use carefully.

Typical Amount: 6-12 oz per gallon (varies by strength)

Mixing Best Practices

🎯 Start Weak, Increase as Needed

Begin at 0.5% for unknown conditions. You can always make it stronger, but you can't undo plant damage.

💧 Water First, Then Chemical

Fill your bucket with water first, then add chemicals. Prevents splashing and ensures proper mixing.

🌿 Protect Plants

Pre-wet plants, cover sensitive areas, rinse thoroughly after the job. Neutralize if needed.

⏱️ Allow Dwell Time

Give chemicals time to work. Don't rinse immediately, but don't let them dry. Re-wet if needed.

🌡️ Temperature Affects Results

Heat speeds chemical reaction. In summer, use slightly weaker mixes. In winter, you can use slightly stronger.

🔄 Mix Daily

SH loses strength over time. Mix only what you need for the day. Don't store mixes — they degrade.

Safety Reminders

PPE is non-negotiable: Goggles, gloves, long sleeves, chemical-resistant apron
Never mix chemicals: SH + acid = chlorine gas (deadly). Keep acids separate
Ventilation matters: Work in well-ventilated areas. SH fumes are no joke
Read the label: Every product is different. Manufacturer instructions trump generic advice
Have a plan: Know what you'll do if chemicals get on skin or in eyes. Have rinse water ready