Power Wash - Deck Help Needed

[Bob Moyer]

Our church is conducting a community help program on Saturday; we have about 150 volunteers stepping out to do work in the community; we are helping families/widows/elderly with work that they can not do themselves.

I have been assigned to oversee the project at a home of a woman who's husband passed away over a year ago.

She has a deck that was painted and it is in need of a lot of TLC; I was told that a power washer would be the best way to remove the peeling paint and to prepare the deck for the application of a clear preservative.

Is this the best approach; what will I need to do in preparation, will we need to sand? I realize we will not be able to apply the preservative until the deck has dried out.

All suggestions are appreciated.

Thanks:D

[Mike Heidrick]

A lot of this will depend on the pressure washer's PSI. How big is the machine you will use?

What happens if you remove the paint and the deck is not in a good enough condition to safely use? How liabale is your group if this happens?

How old is the deck?
What is the deck made of?

[Bob Moyer]

A lot of this will depend on the pressure washer's PSI. How big is the machine you will use? I will be renting, what should I look for?

What happens if you remove the paint and the deck is not in a good enough condition to safely use? How liabale is your group if this happens? Actually the deck where you walk no longer has paint on it, it is the railing that we need to remove the paint. It is my understanding that a cleaner needs to be applied to the deck.

How old is the deck? 7 years old
What is the deck made of? It is pressure treated lumber.

[Tom Godley]

Be very careful with a power washer - on wood they should just be used with the wash head to remove grime. This will also remove some of the very loose paint -- just as a strong hose would do.

To actually use the pressure head requires more knowledge of the unit and the wood in question - you can destroy the wood very quickly.

Unless you can get all of the old finish off of the deck, i do not see how you could use a clear finish anyway.

You may be better off just cleaning it and going over the whole deck with a good latex stain suitable for a re-coat.

[Joe Vincent]

I've done this exactly once and I don't recall the PSI involved, but if the wood is in decent condition (which it should be if only 7 years old) you should be okay in removing all the old stuff if the pressure is high enough. You'll want to use just enough pressure to visibly clean off the surface of the deck and the paint off of the railings. If the pressure is too high, you could damage the wood or leave a rough surface when it dries. As it is, the surface probably will have a little peach fuzz on it anyway. Just want to minimize this. Use a motion sort of like you would with a paint sprayer. Don't let the washer stay focussed on one spot so that you don't overdue a spot, damage it, and leave it looking different than the rest. There will be some trial and error, but you should be able to get the hang of it. It takes longer than you'd think (at least it did for me). If you're using a power washer, I'm not sure you really need to use any type of cleaner as the machine will get the job done (others may know better). Depending on how the deck looks afterward, you may want to go with a clear sealer or perhaps a stain / sealer combo if you think that would cover up any inconsistencies in the wood finish. Depending on how open the pores of the wood are, this sealing process can also take longer than you'd think as the wood drinks up the sealer. Good luck.

Oh, and if you do end up doing any sanding for any reason, wear a respirator because of the treated wood.

[Mike Parzych]

Most rented power washers are in the 4000psi range which is probably too high a psi for most uninitiated users. I've got a 2200psi and it's enough to do the job.

That's not to say you can't use a rented one, but it will take more caution by the user, as that much pressure - used too close - can blow out softwood on a deck. It's a "touch" thing but I'd say having the nozzle any closer than a foot from the deck will eat some wood out. For the paint that doesn't blow off easily, it will take wood-damaging closeness to get it off. So don't try too hard.

Joes right on the motion - a sweeping motion that starts and finishes with the nozzle at about a 45 degree angle from the wood. Ending it too abruptly will leave a noticable "clean" mark lighter than the rest. It's best to go perpindicular to the boards rather than along the length for this reason.

And you'll get wet! I've worn my waders - no kidding - when doing it. An oil based penetrating finish is the way to go. Anything that sits on the surface will come off soon. Thompson's Water Seal is a parafin based product and utterly worthless.

[Joe Vincent]

As Mike said, you'll get very wet. Soaked in fact. Which reminds me: you should wear eye protection because the force of the water will send water AND likely wood splinters shooting everywhere. Safest would be to wear goggles that have a seal so nothing can get to your eyes.

[jason lambert]

This is just my take but you should never use a power washer to remove paint unless it is flaking and you are not using it that strong. The reason is a pressure washer on wood will actually remove the softer wood in between the grain leaving a ruff surface more prone to splintering. I know this because I have done it. Newer wood will not be as effected so you may be able to get away wtih it. But a chemical stripper and sander usally is the best way. But not easy.

[Rich Engelhardt]

Hello Bob,
I'm half way through the process of removing 2 year old paint from a treated deck.
We've been using a 1350 psi Karcher electric.
It doesn't have enough pressure to remove the paint excpet when it's on the round jet setting. The fan setting doesn't do it on the little Karcher.
We're looking at getting an 1800 psi model in the next week or so.

In the past, I've used a gas powered rental w/2800 psi.
That worked well on the fan setting.
It did leave the surface scarred and fuzzy, but a quick once over with a belt sander fixed that.

[Brian Goulet]

Bob,

I'm a power washer by trade and have cleaned hundreds of decks. What you face is no small task. The only way to completely strip off old latex sealant (or paint) is to use a latex stripper that's about $40 a gallon and must be hand painted, left for an hour, and stripped off with the PW. The stuff is toxic too. If it's mostly wood with some latex on it, use a chemical stripper (buy it anywhere), washing it off like everyone's described already, then use a brightener (oxalic acid). You basically have no choice but to put on a latex-based sealant. Forget clear, it's not going to happen.

If the deck is mostly covered in the latex with little exposed wood, just clean it with a mixture of chlorine and laundry detergent (you heard me), LIGHTLY clean with the PW (no "stripping", just rinsing really) and reapply a latex sealant.

I hate latex sealants because once you go down that road on your deck, it's difficult and costly to correct it.

[Bob Moyer]

Bob,

I'm a power washer by trade and have cleaned hundreds of decks. What you face is no small task. The only way to completely strip off old latex sealant (or paint) is to use a latex stripper that's about $40 a gallon and must be hand painted, left for an hour, and stripped off with the PW. The stuff is toxic too. If it's mostly wood with some latex on it, use a chemical stripper (buy it anywhere), washing it off like everyone's described already, then use a brightener (oxalic acid). You basically have no choice but to put on a latex-based sealant. Forget clear, it's not going to happen.

If the deck is mostly covered in the latex with little exposed wood, just clean it with a mixture of chlorine and laundry detergent (you heard me), LIGHTLY clean with the PW (no "stripping", just rinsing really) and reapply a latex sealant.

I hate latex sealants because once you go down that road on your deck, it's difficult and costly to correct it.


Thanks for all of your suggestions - however, entering latex stripper in a web search produced interesting hits.:eek:

[Brian Goulet]

Hahaha...yeah, sorry to send you on the wrong path ....especially for a church project!!

A decent latex product is Behr Acrylic Latex deck sealer, tintable to a million different colors. It's basically paint. I'm not a fan of Behr products but that's one that I use when I have to.

[Jason Roehl]

I wouldn't go the pressure washer route, for many of the reasons mentioned. You don't need a full-blown stripper per se, but there are "Deck Stripper" products out there that do an excellent job. I've used the Flood brand product before and it went pretty fast. I forget if I used a pump sprayer or a brush, but then you hit it with a stiff-bristled scrub brush, let it sit for 15-20 minutes, then rinse it off. The deck I did had about 4 coats of solid-color stain (this could be what you're looking at), because the owner told he had been putting on another coat every other year. It all came off in one application.

To get paint totally off wood when it's not that old, you need 4000-5000 psi, and at that point you'll be damaging wood. Also, it takes much longer to dry properly after pressure washing like that than you might think--months, not weeks. It's not worth it.

[Steven Hardy]

I use pressure spray on cedar sideing,pressure treated decks and I use it for paint removal. I have been successful at this for well over 25 years. I'm not sure where some of the pressure figures have come from here...but 2500 pounds is more than enough to remove GOOD paint from a car or gel coat from a boat, let alone from a wooden deck.
Deck wands are useful for a casual cleaning but they are not what you need for paint removal. For paint removal you need a high flow (3-4 )gph rotary nozzle after you have presoaked the deck in a TSP substitute.When you wash,blast at less than a 45 degree angle. There is a high probability of raising the grain but the same situation exists with using any powerful soap or chlorine bleach for that matter. It dissolves cellulose. With practice and adjusting the distance ,you can minimize the damage..the key thing is to keep the angle shallow.

Another tip for you...to soften the latex paint,test spot a small section using paint brush cleaner applied with a paint brush.Let it sit for about 5 mins. (Check that the cleaner is water soleuable.)