House washing is one of the most effective ways to protect your home’s exterior, yet it’s also one of the most misunderstood services. Many homeowners have questions about pressure, chemicals, safety, preparation, and whether house washing can actually damage their home.
These are valid concerns — and asking them before booking a service is exactly what responsible homeowners should do.
This guide answers the most common house washing questions we hear from customers across New Zealand, clearly and honestly, so you know exactly what to expect before, during, and after a professional house wash.
Do You Use High Pressure to Wash Houses?
No — professional house washing does not rely on high pressure.
Reputable exterior cleaning companies use a method called soft washing, which relies on:
- Low water pressure (similar to a garden hose)
- Specialised cleaning solutions
- Dwell time to break down mould and grime
High-pressure washing can:
- Strip paint
- Force water behind cladding
- Damage seals and flashings
- Cause long-term moisture issues
Soft washing removes contamination chemically, not forcefully, which is why it’s safer and more effective.
What Pressure Is Actually Used During House Washing?
House washing pressure is intentionally kept low.
Typically:
- Pressure is only strong enough to rinse surfaces
- No blasting or aggressive force is applied to walls
- Sensitive areas are cleaned with extra care
The cleaning power comes from the solution, not the pressure.
This is especially important for:
- Painted weatherboard
- Plaster and stucco
- Modern cladding systems
- Older homes with aged paint
What Chemicals Are Used in House Washing?
Professional house washing uses purpose-designed exterior cleaning solutions, not harsh industrial chemicals.
These solutions are formulated to:
- Kill mould, mildew, algae, and bacteria
- Break down grime and organic staining
- Be effective at low concentrations
- Rinse away cleanly
They are not acid-based and are not the same as household bleach poured at full strength.
The key difference is correct dilution, correct application, and correct rinsing.
Are the Chemicals Safe for Plants and Gardens?
Yes — when applied correctly.
However, it’s important to understand this clearly:
- The solutions are designed to be plant-safe when used professionally
- Pre-wetting gardens is standard practice
- Thorough rinsing is done during and after washing
- Overspray is controlled carefully
In professional house washing, plant protection is part of the process, not an afterthought.
Problems typically only occur when:
- Chemicals are mixed incorrectly
- Surfaces are not rinsed properly
- DIY methods are used without knowledge
Will House Washing Kill My Plants or Lawn?
When done properly — no.
To protect plants:
- Gardens are pre-soaked with water
- Delicate plants may be rinsed during the process
- Final rinsing removes residue from leaves and soil
If you have particularly sensitive plants, it’s always a good idea to let the team know beforehand so extra care can be taken.
Is House Washing Safe for Pets and People?
Yes, with simple precautions.
During house washing:
- Pets should be kept indoors or away from the work area
- Children should not play near freshly cleaned surfaces until rinsing is complete
Once rinsed and dried:
- Surfaces are safe
- No harmful residue remains
- Normal use can resume
This is standard practice across the industry.
Do I Need to Close All Windows and Doors?
Yes — this is important.
Before house washing:
- All windows and doors should be fully closed
- Any windows with faulty seals should be identified
- External vents should be secure
House washing uses low pressure, but water is still present. Closing windows prevents moisture entering the home.
This simple step avoids interior water issues.
Should I Bring Laundry Inside Before You Arrive?
Yes — always.
Laundry, outdoor cushions, and soft furnishings should be:
- Brought inside
- Covered
- Moved away from the house
While solutions are diluted and controlled, removing items eliminates any risk of spotting or residue.
Do I Need to Move Outdoor Furniture or BBQs?
It’s recommended.
If possible:
- Move furniture slightly away from walls
- Clear access around the house
- Remove lightweight items
This allows:
- More even cleaning
- Better results
- Faster completion
If moving items isn’t possible, most teams can work around them.
How Long Does House Washing Take?
Most house washes take:
- 1.5 to 3 hours, depending on:
- House size
- Level of buildup
- Access around the property
Heavily soiled homes or multi-storey properties may take longer.
Do I Need to Be Home During the House Wash?
No — in most cases.
As long as:
- Access is provided
- Windows and doors are closed
- Pets are secured
The work can be completed while you’re away.
Some customers prefer to be home for peace of mind, but it’s not required.
Can You Wash a House When It’s Raining?
Light rain is usually not a problem.
However:
- Heavy rain can dilute cleaning solutions
- Windy conditions may reduce control
- Severe weather may require rescheduling
Professional operators assess conditions on the day to ensure safe and effective results.
How Long Will My House Stay Clean After Washing?
This depends on:
- Climate
- Shading
- Surrounding trees
- Proximity to the coast
On average:
- Homes stay visibly clean for 9–12 months
- Shaded or coastal homes may require more frequent washing
Regular maintenance prevents heavy buildup and permanent staining.
Does House Washing Remove Mould Completely?
Yes — when done properly.
Soft washing:
- Kills mould at the root
- Removes visible staining
- Slows regrowth significantly
However, mould spores are always present in the air. Over time, regrowth can occur, which is why regular maintenance is important.
Is House Washing Better Than Water Blasting?
For houses — absolutely.
Water blasting:
- Uses high pressure
- Risks paint damage
- Can force water behind cladding
Soft washing:
- Is safer
- Lasts longer
- Protects surfaces
Water blasting is better suited for hard surfaces, not house exteriors.
How Often Should a House Be Washed in New Zealand?
General guidelines:
- Most homes: every 12 months
- Shaded or coastal homes: every 6–9 months
- Homes with visible mould: as soon as possible
Regular washing prevents long-term damage and reduces maintenance costs.
Why Professional House Washing Is Worth It
Professional house washing:
- Protects paint and cladding
- Extends repaint cycles
- Improves street appeal
- Reduces future repair costs
It’s one of the highest ROI exterior maintenance services available.
What Should I Do to Prepare Before You Arrive?
Quick checklist:
- Close all windows and doors
- Bring in laundry
- Move outdoor furniture if possible
- Secure pets
- Identify any known issues
That’s it — the rest is handled professionally.
Request a Quote for Professional House Washing
If you still have questions or want to book a professional house wash, the next step is simple.
👉 Request a Quote:
https://www.metrowaterblasting.co.nz/
📞 Call anytime:
0800 997 997