Cleaning new leaf-stained PT deck

Larry KahnNovember 16, 2009

Had a new PT deck installed last spring. We do a ton of container gardening and were told to try and keep soil/leaves from accumulating on the deck since there could be mold problems, so we've been doing our best. In late summer we cleaned and sealed it using Sikkens SRD semi-transparent. Looked fine at that point.

Over the past month, the leaves have been raining down and it was hard to keep up with sweeping them off. Plus we were away for a week during the worst of it. After getting most of them off, the deck was REALLY gray and dingy, so today I went out and used our low power electric pressure washer to see how that would do. Got perhaps 80% of the dirt off but some of the stains are a bit more persistent. A couple of questions given that this will be a yearly problem:

1) If I pressure wash the rest of it before winter to try and remove at least most of the dirt, will that "destroy" the sealant that was put on a few months ago?

2) If using the electric PW is safe, are there soaps or cleaners I can use in conjunction with that to get the rest of the dirt off? Since we have a lot of landscaping near/under the deck I doubt we'd want to use something like bleach.

3) If the solution is using a high powered PW in the spring, I assume we'd need to reapply the sealant. I was hoping to have to do this perhaps every other year, but doing it only on the horizontal surfaces where it's now dirtiest wouldn't be a horrible chore.


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Hi Larry. Cleaning your deck is one of those maintenance neccesities, unfortunately many people are misquided. I recommend you go to one of the home centers and find a cleaning product that contains percarbonate. The product does not contain bleach and 'bubbles' dirt and grime up and out of the wood surface. Bleach should never be applied to wood as it is now known that the bleach breaksdown wood fibers. Use low pressure to avoid tearing away the delicate wood fibers also. The cleaner will not harm your sealant. You should anticipate however that the sealer will stop working in about one year. You can test this by taking an eye dropper and dropping water onto a dry section of the wood. If it goes into the wood fast, you know the sealer has degraded, as most organic sealers do. If the sealer is still present, the cleaner should do a pretty good job of removing the dirt and stains. If the sealant has degraded and the wood absorbs water quickly, I recommend you clean the wood and then apply a brightner. The brightner is acidic and removes many stains. Be sure to wet the surrounding areas well before applying the product and make sure you read mixing and application instructions. Most brightners need only to stay on the wood for about 5 minutes before rinsing thoroughly. Hope this helps.

    Bookmark   November 25, 2009 at 6:39AM
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