Pressure Washing an Older Weatherboard House

21-Nov-2018 By BWS
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Pressure Washing an Older Weatherboard House

You want to give your lovely old weatherboard home its first pressure wash. The house has not been repainted in many years.  No problem, as long as you are careful and make some preparations in advance of the wash.  

1.  First, do your own preliminary pest check.  The pressure wash is likely to flush out any lurking creatures but it is preferable to have an idea of where they are beforehand. It's best to be prepared for that angry swarm of wasps or the disgruntled copperhead who's been hibernating under one of the boards. Ants, spiders, beetles, cockroaches, rodents and snakes are all possible residents of the house walls. All these and more have all been found living under loose weatherboards, whether in urban or rural locations. 

2.  Check for loose flaking paint. If there is a significant amount you may want to have it tested for lead. If the house has not been repainted since the early '70s it is likely that lead levels present a potential health risk. Whether you choose to dry-brush or scrape walls before the wash, or to go straight into pressure washing, a tarp secured on the ground below the wall will catch any paint flakes, ready for their safe disposal. Covering the ground before pressure washing can also protect plants and stop wet soil splashing back up onto your washed wall.

Here is a link to Australian government guidelines on dealing with lead contamination in older houses, with specific reference to house paint removal in this document

3.  Check for loose nails. If any seem questionable, hammer them in securely before the pressure wash.

4.  Check all windows and frames. If any of these are cracked, crumbling or cannot be secured tightly, they can be masked with waterproof masking tape so that none of the pressured water disturbs them or enters the home. Spraying the windows, other than with a very low pressure, is to risk breaking them.

5.   Check fascia boards to see that they are secure and intact. Fascia boards help to hold the gutters in place and to protect the roof. Over the years they are exposed to prolonged damp conditions and may start to rot. If that happens they can be repaired or replaced at any time. For pressure washing, it helps to know the condition of the fascias before you begin.  

6.  Be aware of all electrical points or wiring entering the building from the outside of the walls. Seal off any small holes that could let spray enter near electrical wiring, or avoid those spots and clean them manually.

7.  Is mould a potential threat in your area?  If so, you could include a mould inhibitor in your detergent. This is because the pressure spray may cause damp to penetrate under the boards of some older homes. 

8.  Test your spraying on an inconspicuous part of the building, before you begin. Using a fan spray, start with a low pressure then gently increase it until you discover the best pressure level for the timber on your house. If the water starts to etch into the wood or to remove too much surface, the pressure is set too high.  

9.  During the wash, generally stand at least one and a half metres away from the wall, and the water should be spraying at about a 45 degree angle to the weatherboard surface.


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