Water Blasting – Will It Damage My House?
The simple answer is yes it can do if the water blasting is being done by an untrained, unskilled operator. The house in the photo is constructed out of Cedar, which as you all know is a relatively soft timber and many house washing companies will not even attempt water blasting such a property.
Over the course of the past ten years, AWL has restored almost 300 Cedar clad properties in and around the North Shore and the greater Auckland area. We take particular care to ensure that each property is lovingly restored to the point where many clients have stated their homes look almost as if they had been freshly built.
Water Blasting – What Are The Risks?
There is a growing concern about the potential damage that water blasting can cause when used by untrained individuals to clean the exterior of buildings.
Water blasting equipment used to be available only to professional cleaning companies but now they are freely available to anyone. You can now purchase one at your local hardware store, you can hire a machine and all without needing any knowledge or proper understanding of how to use them.
It’s important to periodically clean and maintain exterior wall cladding’s not just to keep them looking pristine but also to prolong the life of those materials.
Most building materials are not designed to withstand the water pressures generated by most of the ‘off the shelf’ water blasting equipment.
The average New Zealand homes should be designed to withstand maximum pressures in the 1.5 – 2.5 kPa range, which is the equivalent of an 180 km/hr wind gust.
The problem is that many domestic water blasting machines have a maximum pressure rating of between 1500 to 1885 psi. Couple that with the standard 8300 kpa nozzle, which is usually supplied with the machine and in the hands of the wrong person that can cause a forcible impact on walls and joints!
Standard building materials, joints and seals used on the average New Zealand house are simply not designed to stand up to these pressures. Without the proper equipment and training water blasting can;
- damage soft weatherboards
- dislodge the mortar from brick joints
- blow off paint film along cladding edges
- dislodge sealant used to ensure waterproofing
- force water into joints and wall cavities…. and
- erode thickness of the protective paint layer – and much more.
Water Blasting Equipment Should Never Be Used Indiscriminately
Used indiscriminately, water blasting can damage your home. Unless you have had specific training appropriate to the surfaces you are wanting to clean, then you may want to leave it to the professionals.
There are, of course, occasions where the proper use of water blasters, on certain materials, may be appropriate for you to handle yourself.
If you prefer to clean the house yourself then you are better off sticking with a soft brush and the garden hose.
Simple Rules For Water Blasting Safely
To reduce the risk of damaging cladding and joints through water blasting, follow these simple rules;
- Always read the operating manual before doing anything.
- Familiarize yourself with any and all safety requirements.
- Check the maintenance and warranty specifications detailed by your roofing and cladding manufacturers. Some warranties can be voided through incorrect methods being utilized.
- Use the lowest available pressure setting.
- Set the nozzle on ‘wide spray’ and maintain it at least 500 mm clear of the building’s surfaces.
- Don’t hold the nozzle up close to a surface to dislodge stubborn dirt – use a brush or broom for that.
- Never point the nozzle directly at joints or aluminium joinery, because many of these rely on sealants for their weather tightness, which can be dislodged by high pressures.
- Use cold water and lite detergents only.
- Use infrequently.