There is a lot of debate surrounding the use of soap in pressure washing, and much of this debate stems from disagreements pertaining to when it can be used and whether or not it is even useful in the first place. Suffice it to say that most pressure cleaning jobs will not necessitate the use of soap, since the combination of high pressure water sprays as well as some cleaning chemicals would be more than enough to get the job done once all has been said and is now out of the way.
That said, the conversation tends to change entirely if you want to hire the best power wash to clean up your patio. The reason behind this is that patios are very different from other parts of your home, with one of the main differences being that they are more likely to be made of wood than might have been the case otherwise. Hence, you might need to use a bit of soap to break dirt down, otherwise you’d be forced to take the pressure to an unmanageable high level that you would come to regret a fair bit.
Soap allows you to soft wash your patio, and a majority of experts would agree that wood is better served by this method as opposed to pressure cleaning. What’s more is that soap is washed off quite effectively from wood instead of sticking to it which would be the case with concrete that is quite greasy. Patios are a rare example of surfaces that might be better off if soap is used, so it is crucial to judge these things on a case by case basis.