Commercial Building Wash Auckland NZ

Ultimate Auckland Commercial Building Wash Guide

Welcome to the Ultimate Auckland Commercial Building Wash Guide. This will provide you with insight into the tasks and equipment involved in all different types of small to large commercial building washing techniques and building wash services. It covers building wash equipment, licenses, different commercial building surfaces, windows and glass, abseiling and more. This guide gives a general overview of some of the most common things involved in commercial building washing but does not replace common sense or experience. 
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Commercial Building Wash Services Guide – Auckland NZTS

Intro to Commercial Building Washing 

To wash a commercial building well you should already have a good understanding of exterior cleaning, water blasting, soft washing and window cleaning equipment, heights safety and water blasting, soft washing, window cleaning technique.

Becoming competent in building washing

To become competent in building washing firstly, there is the understanding of the building washing equipment and chemicals and what it is all used for. Secondly, there is becoming familiar with all the techniques involved in removing dirt, moss and mould. Thirdly, there are hundreds of different materials and products that present themselves in all different stages of weathering / aging and often have had a multitude of different sorts of maintenance which have been carried out and / or applied to them. 
Complacency, carelessness, and underestimating the difficulty of washing some of these surfaces is the main cause of error or damage within the industry. To get a good grounding in the industry you should look to become competent in residential washing as it presents all of the challenges of commercial building washing but in bite sized manageable pieces. 

Why wash a commercial building?

There are many reasons to wash the exterior of a building. Clear, mark free windows will lift the street appeal of any shopfront or office and clean signage is an indicator to potential clients that a shop or office takes pride in presenting themselves at their best. An exterior building wash is a very effective measure to extend the life.

span of surfaces around a building. Build-up of contaminants like diesel dust, moss and mould, bird droppings, construction dust and debris, general breakdown of organic matter like leaves and pollen will all add up to the faster degradation of a building’s surfaces. 

Building Washing Equipment 

As we well know, having the right equipment for any job will assist in cutting down on hard labour and time taken to complete a task as well as lifting the end quality of a job done. This is no different for water blasting and building washing. In this section we cover off some of the different building wash equipment and what it’s used for.

Water Blasters

You will need an array of equipment to successfully wash commercial buildings. The first of which is a selection of water blasters. You will want the ability to adapt your flow and pressure to wash buildings well. 

High Flow Water Blaster used for Building Washing and Roof Washing

If you have a commercial building wash job that requires a lot of time on the trigger of a water blaster E.g. Commercial Roof washing, large building elevation wash or commercial concrete washing, then you should have a water blaster that is capable of pumping a high volume of water. Around 25 to 35 litres per minute. The lower pressure will help to preserve a commercial roof’s surface while washing it. The high flow will help you to speed up your work rate. 

If your equipment is too small on an extra dirty, large commercial roof wash job can cause damage to commercial roof surfaces and cost you days of your time and disruption to clients’ operations. NZTS commercial roof wash water blaster of choice is a Honda GX690 and a high flow pump around 25 to 30 Litres Per Minute with a pressure of around 2000 to 3000 PSI. 

Good washing technique and the right fittings and attachments will help to make commercial high flow washing easier when on a large roof or concrete wash job. Some building wash operators will prefer to use a pole with a ball valve to eliminate trigger use although this is not best building wash practise as it can easily be dropped or turned on without an operator on the pole. The unmanned attachment can then spray out of control and cause damage, injury and / or flooding. We find it is best and safest to use a 1.2 to 1.6m lance without a bend in the end, attached to a standard trigger. The straight water blasting lance takes a lot of the kick out of the lance and takes the stress off your body. 

These high flow water blasters are also great when used with a surface cleaner aka whirl away to clean large areas of concrete.  

Medium Flow Pump & Water Blaster for Building Washing and General Tasks 

Medium sized equipment e.g. GX390 with a 15 to 20 litre per minute pump is a good all-round building wash machine. With the right building wash technique, it is perfect to use on retail buildings, light commercial buildings, smaller roof washing up to 1000 Sqm. This size machine is also good for small commercial paths or decks up to 100 Sqm. Using this lower flow water blaster and pump on larger size roofs or surface cleaning will cost you a considerable amount of time.

Small Low Flow Pump and Water Blaster for Abseil Building Washing / Roof Access 

A small water blaster for abseil washing can be handy for ease of transporting equipment through manholes to set up on roofs. The lower flow is also easier to control when washing from ropes. Small machines are also very good at soft washing if you are washing around wooden window frames or door frames.

High-Pressure Pump and Water Blaster for Roof Pre-Paint Preparation

A high-pressure water blasting, 4000 PSI or more is ideal for surface preparation. High pressure is ideal for removing any existing lichen, and its roots (Rhizines) which anchor themselves to (and often etch through) roof coatings over a period of 5 to 10 years. High Pressure water blasting will also remove oxidised paint surface. Using a water blaster with lower pressure may not remove all oxidised paint which compromises the bond that your base coats of roof paint are able to make with the roof, in turn decreasing the lifespan of your roof paint. 

Commercial Grade Hose, Fittings and Attachments 


High Pressure Hose 

2 wire water blasting hose is ideal for commercial building washing. The sturdy design of the wire running through the hose will eliminate kinks, stand up to being driven over by commercial vehicles, will minimise blowouts and have a lifespan of up to 2 years. 
At NZTS we like to 3 x 30 metre lengths. 90 metres will get you a good distance around commercial buildings or up and over roofs without having to move your unit too often.
The only drawback is the extra weight of 2 wire hose for building washing can be heavier to handle and move around site. Some operators use one wire and replace more often or just use one length of 1 wire hose to take some weight off the trigger and make working a little less strenuous. 
1 wire hose is more suitable for abseil washing given the lighter weight and easier handling when washing buildings while suspended.


Fittings make the connection between all the components through building washing / soft washing / water blasting and spraying units. Good fittings and replacement O rings are crucial throughout the whole setup. All connections from tap to tank to pump, through high pressure hose, trigger and nozzle should be good working order. Worn out fittings or O rings will leak and wastewater and chemical, also the drop in pressure through the system will affect the operation of pump and venturi. 

Commercial Triggers and Lances 

Having a wide selection of commercial grade triggers and lances is essential to efficient and effective building washing. Shorter lances from 50mm to 500mm are great for washing tight spaces around buildings like in between buildings, fences that are close to buildings or washing inside buildings balconies. If you ever have to wash safely from a ladder, a short lance in conjunction with the right pressure, nozzle and low flow will be easier to control. 
Medium lances from 800mm to 1.2m are good all-rounders for washing buildings and roof washing. These lances are often sold with a bend at the end of them just before the nozzle tip. Although this bend can come in handy from time to time it can also cause a lot of “kick” in the wand each time you pull the trigger and be strenuous and hard on the body after a lot of time on the trigger. Be sure you have straight lances with no bend to eliminate the kick and save. Washing with high pressure or high flow. 
Long Lances from 1.5m to 2m are ideal for use when soft building washing is 1 to 3 story. The extra meter of length enables you to reach spots more effectively and increase your range when working safely from the ground. A longer lance can also be an effective tool when soft washing large roofs. The long lance increase enables you to clean a larger area with each stroke. Again, these lances should have no bend in the end when using high flow or high pressure to wash.
Lance extensions from 300mm to 500mm are great little attachments which fit in the end of your quick connect nozzle connection and extend any lance. The extra bit of length can help you maintain a more comfortable posture when washing commercial roofs and save you from injury in the long run. 

Ceramic Nozzles 

High quality ceramic nozzles will assist in washing by delivering an even pressure across the stream of water exiting the nozzle. Cheaper metal nozzles can have high pressure points at the outside edges of fan nozzles making it harder to achieve quality results when building washing. 

Nozzle guide

When washing a building you’ll want to have a few different nozzles at your disposal. A black nozzle is used to apply soft wash chem by opening up a Venturi and drawing soap and / or chemicals into the system. Typically, a venturi mixes down around 10:1 when fully open. This nozzle is sized 400 and 40 or 50-degree angle.

White nozzles are great rinsing and sweeping nozzles. They’re a versatile nozzle as you can both water blast and soft wash really proficiently with them. They spray water out at a 40-degree angle spreading out the pressure quickly once it leaves the nozzle tip. Great for dropping pressure when close up soft washing a roof or commercial building. Another tip is to drop the throttle of your water blaster for even softer results when soft washing any building that cannot afford water ingress. 

Green nozzles are the next angle down from a white nozzle. Green nozzles spray at a 25-degree angle and focus more of the pressure at one point. A good water blasting nozzle that still gets enough spread to cover ground quickly. 

Yellow nozzles are a tighter angle again at 15 degrees. These are good for detailed work around garden path edges and digging out moss from between paving stones. If you need to direct water higher up on a building, they will achieve a result from more of a distance than the white or green nozzle would be capable of when building washing. 

Red nozzle is a 0 degree nozzle or pencil nozzle. This nozzle is a great, powerful tool that can change the whole way you approach building washing. With the red nozzle’s reach and force at a distance it will enable you to speed your work rate up when washing buildings. Operators must be diligent when using this nozzle as mishaps will cause damage to building surfaces and be costly and time consuming to repair. 

Turbo Nozzles 

Turbo nozzles are another great tool when used properly for surface prep. The rotary motion combined with a 0-degree stream of water delivers a powerful cleaning force that should only ever be used on pre paint roof washing when the roof’s substrate is in good condition and also concrete surfaces if you really need to beat it up. This nozzle will leave circular lines when used to clean surfaces such as tarseal or wooden fences etc. 

Whirlaways / Surface Cleaners 

Whirlaways are great tools when you have the right water blaster and pump for washing large areas of concrete. Great for car parks, ramps, driveways, sometimes flat roofs (only if it is set up so that the metal spinning nozzles don’t hit the roof or roof screw or nails when washing. With a 30 litre per minute pump you should be able to wash around 150 sqm per hour provided that there is good drainage around the washing site. 

Window Cleaning Equipment

Investing in quality window cleaning equipment will increase your ability to clean hard to reach areas and complete work to a high standard when building washing and / or window washing. Mop and blades with elbow/pivoting heads are the best to achieve this, along with telescopic extension equipment. NZTS prefer Sorbo window cleaning equipment. 

Carbon Fibre Water Fed Poles 

Lightweight water fed poles are ideal for washing tall faces of glass or aluminium building materials and cladding that are prone to show spotting. These poles range in size but go up to 18m to use on 4 to 5 story building washing and window washing. Used in conjunction with a purified / deionised water filtration system with resin will enable you to get a far better result with less spotting and a shinier finish. 

Training and operator licenses

Water blasting and building washing is an unregulated industry. There is no formal training, code of conduct or unit standards that govern the correct use of water blasters or washing buildings. To develop the skills to wash effectively and safely is at least a 6-month process and also a willingness to care enough to learn how to complete work to a high standard. If you are wanting to grow a building wash company. You should develop your own procedural documents that cover off the exact way in which surfaces are washed or prepared and the unit standards that your staff or contractors go through to become proficient building wash operators. There is, however, some formal training (which we have listed in this section below) that your building wash staff, or operators should have completed to assist with safety and awareness.

Heights and Harness Course – Site Safe 

When washing buildings, you will often find yourself having to complete work at height. So, this course is a great intro to giving yourself the basic knowledge to start keeping you and your team safe. 

The heights and harness course at Site Safe covers off the importance of minimising or eliminating all risks involved with working at height and the basics of using rope and harness and other fall arrest systems correctly.  
The course is geared towards the construction industry, however, there are many good bits of information to takeaway and put into practice when washing commercial buildings. Completing this course will give you and your team your Site Safe Passports enabling you to conduct wash on commercial building sites. 

EWP – Elevated Work Platform License

To wash many commercial buildings the best way to access them will be by an EWP. Being prepared and holding your EWP license will undoubtedly come in handy. There are a few different types of EWP which the training course should cover off. Knowing what sort to use for which type of building takes a bit of experience and a bit of forward thinking. Typically access equipment hire companies are good at providing advice on which piece of access equipment will be ideal for which sort of situation. Be sure to budget for this in your building wash quotes and proposals. 

First Aid Course 

Having your building wash operators trained in first aid will ensure the best first response to any accident or injury on or around your building wash site. 

Chemical Use 

Chemical use and the understanding of what specific tasks they are used for in commercial building washing is essential to achieving great building wash results.

Building Washing Chemicals 

The building wash chemicals you use should vary case by case. Sodium hypochlorite and a soaping agent / surfactant is ideal for heavy mould and lichen i.e. Soft wash. Trans wash is helpful when it comes to road dirt / diesel dust. 

Commercial Roof Treatments 

Quaternary Ammonium Chloride is the active ingredient in moss and mould treatments like Wet and Forget. It’s very effective at cleaning certain sorts of mould from surfaces around a building like roofs and paths. The effectiveness of this cleaning method is based on many variables including time of application, type of organic matter being cleaned, weather, strength at which it applied at, shade around the area being treated, organic matter and/or dampness in the area being treated, pitch of the roofs being treated. To get the right idea of how and if an area will clean up using a treatment you need to speak to someone who has had years of experience in the field. 
Used at correct strengths, Quat has a bonding quality to the molecules which means it attaches itself to surfaces and can have cleaning effects for up to 2 or even 3 years. There are certain situations when it is not safe or effective to use Quat. Be sure to consult a professional before implementing this cleaning method.

Building Wash Guide By Type 


Light Commercial Building Washing / 2 to 3 Story Building Washing

Semi-commercial building washing or small apartment block washing is very much on par with house washing. If you have skills in residential house washing, then you should be able to transfer them to washing these types of buildings. Cladding and access may vary slightly but typically the same soft washing methods will apply. Things to look out for are parapet walls and dividing walls above roof lines (these often get missed or put in the too hard basket as it requires roof access), lichen or mould on the tops of flashings (this too often gets overlooked and without cleaning them mould will quickly return to the walls of the building as rain water washes over the mouldy flashings). 

Be familiar with any cladding cleaning specifications and adjust the cleaning method accordingly. Use purified / deionised water filtration to help with minimising window water spotting.
If there is stubborn lichen or mould to be washed on high building walls, then having the right extension or access equipment is a must. 
When you are dealing with blocks of units or apartments, ensure all tenants and occupants have been notified of the wash to avoid any hassles and to keep any disruption to a minimum. 
Sharing around the water use between units while washing the building is helpful so one tenant doesn’t get landed with the water use for the whole apartment.

Large Commercial Building Washing / 2000 to 30,000 Sqm Roof Washing and Building Washing

Washing very large commercial buildings comes down to having the manpower/or time, water flow, and correct access equipment to make the job run smoothly. Commercial building wash equipment should be utilised as described in Section 2.
Large sites require you to work in pairs to monitor each other’s health and safety whilst working. Access to a fire hydrant standpipe can often be helpful as not all sites have taps outside or the water flow to keep up with what is required to wash a large roof or building. 
Again, all surfaces should be assessed for types of dirt, mould and deterioration so the correct cleaning methods can be implemented, and client’s expectations managed accordingly. 
Having a clear plan and implementing the correct cleaning method from the outset will affect a great end result and minimise any touch ups required at the end of jobs. A methodical, systematic approach to large building and roof washing is helpful to speed up the wash and ensure nothing is missed. 

Retail Building Washing and Window Washing 

Planning is key to washing retail sites and building washing in and around CBD. These sites typically require a lot of glass cleaning at hours that suit the client. Automatic glass sliding doors must be lockable for the duration of the clean. Make arrangements for cleaning and/or access during hours that are convenient for the clients / tenants. Glass canopies may require some access equipment and / or traffic control. Bin areas and concrete cleaning is another task regularly carried out in the city. Ensure you have good degreasers and strong cleaning products to effectively sanitise and eliminate smells from the filthier loading bay / back entrance / bin areas.

School Building Washing 

Washing school buildings can vary from washing small modular classrooms to massive sports gymnasiums, or modern school buildings up to 15,000 square meters. You may also encounter historic buildings, chapels or halls. Being knowledgeable in your approach and having the skills on hand that understand all the different materials and cladding cleaning requirements will get you through school building washing and achieve a great result. 
Having your health and safety procedures in place and having any staff or building wash contractors police checked is typically a requirement for contractors that work on school grounds. Work on school buildings is usually better carried out over holidays when there are no activities on at the school. Be sure to work with the school on fitting into their budget and advising on long term plans that decrease the overall maintenance spend and increase the lifespan of surfaces around school buildings. 
Sweeping up, washing concrete and cleaning gutters are some other common tasks at schools.
Check tank levels if the school is on tank water and be sure to disconnect if roofs are being washed or if the buildings walls above roof lines are being washed. 

Abseil High Rise Building Washing 

Washing a building from ropes requires all the appropriate training and site-specific safety and rescue plans. Certified abseil rated anchor points on roofs are required or rigging up to solid structures is a requirement when abseil building washing. Building washing and window cleaning methods vary depending on each customer’s needs. Abseil building washers should understand the difference between soft washing and water blasting and between Pre paint washing and maintenance / warranty washing. 
Abseiling is a great way to gain access to perform a range of other tasks on buildings like repairs, maintenance, painting and installations of signage or putting up bird proofing solutions. 

Washing on Building Sites 

Building sites are busy places, you must be prepared for delays and changes onsite to fit in with other workers onsite while trying to complete your exterior cleaning work. 
Ensure you have been inducted to site and are familiar with all the other work going on around site and the health and safety and PPE requirements. 
You should be ticketed to work from an EWP if required to do so. In most cases you will also require a Site Safe Passport to be able to carry out any washing work on site. 
When it comes to the building washing work to be carried out on an active building site. Ensure you have considered any over spray towards public areas and also where your runoff water will drain to. Washing on building sites will generally entail a number of different cleaning methods. Low pressure and soft washing of new cladding, etc

Building Wash of Historic Buildings and Iconic Buildings

When it comes to washing historic buildings you really need to know your stuff. You should be an expert house and building washer and know how to avoid ingress and know how to soft wash very well (and also what materials to avoid soft washing). You should also know differences between an array of different historic materials like stone, brick, copper, plaster, and concrete and how to treat each accordingly to achieve the best result. 
Correct assessment of the building during the quote stage is imperative in establishing the building’s condition and areas to be mindful of during the wash. You will need some experience to do so. This will help you to convey any issues / staining / degradation / wood rot / bubbling paint etc back to the client to manage realistic expectations. The ability to conduct minor repairs as you go is another great service to offer especially when you have the access equipment on hand to wash the building. 
The correct access equipment or a competent building wash operator with the correct extension equipment are the best ways to get up close to the work and eliminate any damage or marks. Soft chem washing is great for painted surfaces, however, it can be problematic down the line some time after the building wash and can exacerbate efflorescence out of blockwork, stone and bricks. 

Washing Skylights 

Commercial skylight washing should be a gentle and measured process when washing a building. Old fibreglass skylights are prone to holding onto mould in between the fibres. Applying a sodium hypochlorite mix before washing will soften mould and lichen enabling you to wash off remaining mould with 1000psi or less. New skylights are far less fibrous and porous making them far easier to wash especially if they’re maintained with regular building washing. Commercial skylights are typically brittle, and you should avoid walking on them at all costs. It is best practise to be on rope and harness while washing skylights especially if there is no mesh wire beneath them. 

Washing Aluminium and Alucobond Cladding

Washing buildings clad in aluminium or Alucobond products is almost better to be thought of as a window wash. The manufacturers specifications are typically to wash over with a very weak / diluted building wash soap, washed down with a soft sponge or mop and then rinsed off. We find using deionised / purified water systems and soft brush water fed poles achieves the best result. The use of other chemicals or high-pressure washing can void warranties and cause damage. 


When it comes to building washing you are bound to come across oxidisation. Understanding it will make you a better building washer and enable you to give better advice to your clients. 

What is oxidisation?

Oxidisation is a natural process where materials / compounds react and break down over time to include oxygen and lose electrons. This typically occurs anywhere from 3 to 10 years through a coating’s lifespan depending on the situation and the quality of the product. 
What this means for coatings is that their surfaces are literally breaking down / dissolving because of the constant contact with the elements. The integrity of the coating has become compromised and there is no quick fix, it’s the building surface’s way of telling us that the coating has done its job and it’s ready for a fresh coat of paint or replacement.

Testing for oxidisation of paint and coatings 

Visually, the paint or coated surfaces (especially on darker coloured coatings and buildings) will appear dull and chalky once oxidised. Clients will often mistake this for dust or dirt that can be washed away. Unfortunately, this is rarely the case. Physically you will be able to wipe the surface of the coating with a rag or even your finger and see the residue from the coating come away under just a small amount of pressure. Please note that this is far easier to spot on darker coloured surfaces. On lighter colours you will have to look a lot harder to ascertain whether or not oxidisation has occurred. 

Washing Oxidised Surfaces

When washing oxidised surfaces, it is crucial to note the desired outcome for the client. Are they planning to paint or do they just want it to look clean? On dark oxidised surfaces there is little chance that cleaning will meet the client’s desired result. When the dark surface is wet during the clean the surface looks great, after the surface has dried out all the patchiness will be plain to see. If you are washing for pre-paint you should be washing with high pressure which is strong enough to remove all oxidation so that the initial coats of paint have a more solid surface to bond with. Painting over insufficiently cleaned oxidised paint work can reduce the lifespan of a new coating by years. When pre paint washing you will need 3500 psi to 4500 psi to achieve an adequate wash without damaging substrate.

Other Building Wash Related Tips

Washing Bird Droppings from Buildings 

When building washing bird droppings from building surfaces, ensure that you have the appropriate PPE to protect yourself from back splashing of the droppings onto yourself. Use a strong soft wash solution to sanitise the area. Always make clients aware that bird droppings are acidic and are prone to staining and damaging surfaces. This is a good reason to install bird proofing or bird repellent to deter birds from nesting and roosting. 

Building Washing from EWP 

Building washing from an Elevated Work Platform or EWP is required when extension equipment is ineffective, or abseiling is not viable. Getting on top of your work means you can wash down on building ledges or sills that would not be able to be washed effectively from the ground or with extension equipment. 
Using a mobile boom lift or scissor lift is a great way to wash up high and have the ability to cover long faces of buildings without having to lower the platform, lift stabilizing arms and relocate other less mobile pieces of access equipment like cherry pickers and cherry picker trucks. Ensure you are licensed to use an EWP and are working in pairs. Ensure you have mapped out any obstructions on the ground and up high including other vehicles and power lines etc. 

Bird Repellent and Bird Spike Installations 

When installing bird repellent or bird spike solutions on buildings ensure surfaces are cleaned and sanitised. Once dry, cover all surfaces with food grade bird repellent or glue down bird spikes along ledges or wherever you want to deter birds from landing on buildings surfaces. 

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NZTS Auckland