I recently bought a home and hired a contractor to perform general clean up. He pressure washed my composite deck. Afterwards, I noticed the following damage but I'm not sure if he caused it or if it is pre-existing. Before I accuse him, I thought I'd ask the internet's opinion.

What do you think? Does this look like damage from pressure washing?

Deck damage (zoomed in)

Deck damage

Edit: the pressure washer is 2700 PSI.

  • This question is asking for an opinion about what caused these marks. Unless these people are experts in deck boards and have some sort of superpower that reveals answers using two photos as the only evidence, no one here can answer this question. Those do not look like power washer marks. In fact you should have asked, “what caused this damage?” to see if these experts come up with power washer as the obvious answer.
    – jqning
    Commented Jul 10, 2023 at 13:55

4 Answers 4


Is it possible? Yes.
Is it likely? No.
Could it have been done earlier by something heavy? Yes.
Is it worth falling out with the contractor over? No.


The pattern of marks suggests a curved path consistent with using a pressure washer. 2700 psi is enough to do serious damage. The fact that the center of the marks is gouged out is also consistent with where the water is moving fastest when it hits the wood.

Easiest way to tell is to try the pressure washer out on it again.


It's hard to tell. If the bottom of the grooves look more aged or darker (after the wood has dried) then they could have been there before.

I would suggest that you contact the contractor and say something like - "I am seeing some curved marks on the deck, were they there before? Could you come and have a look at them". Then decide what to do.


Short answer:

Yes the high pressure washer did damage the composite wood. Or it exposed the weaknesses. Simple logic: Was it there before ?

  • 3
    Is there something specific about the damage that suggests the pressure washer and not, for instance, damage from deck chairs?
    – user169686
    Commented Jul 9, 2023 at 21:48
  • 1
    @user169686 I was wondering about that also. It could be some sections of the decking were weaker, but it seems a tiny amount to be just from the pressure washer. Maybe deck chairs or something started the damage, and the washer made it stand out more.
    – crip659
    Commented Jul 9, 2023 at 22:10
  • 1
    @user169686 Do you know the PSI of the pressure washer? You don't mention a "high" pressure washer as stated in the answer. A 1600 PSI washer wouldn't damage it. I don't think it was the washer and proving the contractor did it will be hard.
    – JACK
    Commented Jul 9, 2023 at 22:17
  • @JACK The pressure washer goes up to 2700 PSI. Unclear if he used it at maximum pressure.
    – user169686
    Commented Jul 9, 2023 at 22:28
  • 2
    A pressure washer could cause those marks if a needle tip was used, but needle tips are very slow for washing large areas, and the marks would all over, not a few small marks.
    – crip659
    Commented Jul 9, 2023 at 23:40

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