WHY do I have to seal my cedar deck?

srlarsenJuly 20, 2005

OK, I've always thought the reason you spend more money on cedar is because it's rot resistant. Also, I prefer the look of cedar after it has weathered to a soft gray. But now that my husband and I built a new house and have 3 cedar decks, I want to make sure I protect our investment! So, please explain why it should be sealed. If I do need to seal, is there a product that is truly clear? I don't like the look of the dark stains that I always see. Sorry if this is all stuff you've covered a million times...



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Two things:

1) The cedar that most people are using for decks is not as rot resistant as the cedar that was being used 30 years ago. In the old days, cedar decks were built from old growth lumber, which was loaded with oils and natural chemicals that made it highly resistant to insect attack and decay. These days, the wood is coming from new growth, managed forests and it containts lots of sapwood. This wood will decay faster. Some people have seen cedar decks fail within 7 years under the right conditions. Plus, it cracks and splinters. And if it's not kept treated, it generally looks bad after a few years. My humble opinion only. I believe you can still order clear cedar or redwood (heartwood) but it will cost you a fortune.

2) Clear sealers possess no UV protection, so if you use one, your deck will turn gray.

    Bookmark   July 20, 2005 at 2:58PM
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johnplace, couldn't have answered any better. I see more rotted cedar decks in my profession than any other wood. In my opinion, construction grade cedar is a lousy choice for a deck.

Stacie, I just finished a deck today for a customer that had exactly the same thoughts you just shared. When I finished the deck, it was a very warm toned, not overly red, not too dark work of art. He and his wife sat staring at it for about 20 minutes as we packed up. He said if he knew it could have looked this good he would have sealed it years ago. The key is proper prep and choosing the right sealer.

Just to head off the next question.. The products I use are contractor only and the colors I custom blend. Experience has allowed to make some very cool colors (for lack of a better term) Just be sure to get your sealer from a paint store not a home center.

    Bookmark   July 20, 2005 at 4:04PM
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Thanks so much for the info. So now I guess I need to do some research on the best type of sealer to use. What are the disadvantages of using a sealer with no UV protection - just the fact that it turns gray? My dad is going to have a great time telling me "I told you so" when I seal these decks! Oh, my deck is only about 4-6 weeks old, so will I need to powerwash or anything first?

    Bookmark   July 20, 2005 at 4:04PM
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You all raise a question of concern to me. I am considering composite floorboards with cedar railing and wanted to paint the railing a white or possibly white and gray combination. How do I address the "sealing factor" if going the paint route ? Thanks for all your great advice as usual.

    Bookmark   July 20, 2005 at 4:34PM
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John agrees with John and Ken. J

    Bookmark   July 20, 2005 at 5:57PM
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Ok, now my next question - you have said that "under certain conditions" a cedar deck has failed after 7 years. Realistically, how many more years of service will I get from my cedar deck if I seal it every 2 years? Thanks!

    Bookmark   July 20, 2005 at 6:05PM
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I think John H. or Pressurepros might be able to give you a better idea of what you can expect based on their years of experience in the field.

The decks that I am talking about were never sealed (or maybe sealed once), and they were in shady, rainy environments where the wood stayed wet for a longer than average period of time.

I still think you can get 15 years out of a cedar deck if you seal every 2 years with a quality sealer.

    Bookmark   July 20, 2005 at 11:20PM
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How difficult is it for complete novices to powerwash and seal their own deck? I think our deck is about 15 x 25. We just got the house this summer, and it's the first time we've had a deck. It's gorgeous and I don't want to mess it up. However, my brother said it would run me about $600 to have someone come out and wash then seal it. That's a lot of money!

    Bookmark   August 29, 2005 at 9:36AM
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If your deck is cedar, power washing is not recommended because it will blow out the soft grain. I have seen the damage firsthand -- not pretty.

I am not an epxert, but my understanding is that unless you have some sort of old-sealer mess to deal with, cleaning and sealing is fairly straightforward for a novice, although it can be labor intensive. All the knowledge you need is free on this forum.

There is lots of info on this board about the cleaning/sealing process.

    Bookmark   August 29, 2005 at 1:30PM
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Thanks for telling me about the power-washing! I was looking around at the different recommendations on sodium percarbonate and oxalic acid for cleaning and brightening. There is a little of the Thompson's stuff the previous owners sealed it with...along with horrible splatterings on the siding! UGH! Everything they did was that way. I digress...

My husband and I still aren't sure about which stain/sealant to use. I read some recommendations about Penofin being quite forgiving and thought about that, but I really want a natural cedar finish to it. I'm not sure if we can get that out of the wood. The deck is at least 10 years old. It was built rock-solid by the general contractor that owned the house prior to the people we bought from. These people did what my grandmother would call a half-#$%ed job of everything though (again with the digressing), and there's green stuff on the ends of many of the boards. I'm pretty sure it's mold. Also saw advice on NOT using bleach, so I won't even try that.

I will keep searching for info on the forum, but does anyone have a recommendation about whether we should just use our garden hose sprayhead or should we get a slightly more powerful nozzle? This one is great for watering grass, that's about it.

    Bookmark   August 29, 2005 at 2:19PM
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TheresaS, 600.00 is a LOW price. Your deck needs to be professionally done if you want expert results. All the old sealer must be removed, stripped. Cedar will naturally raise it's grain when stripped, so a professional wood restorer will remove as much of the fuzzies as possible. Nails and screws should be re-seated. A professional grade sealer should be considered. For a good consumer product I would recommend Cabot's Australlian Timber Oil. Cedar looses it's natural oils over time. An oil based sealer will help replenish most of the lost oil and protect the wood inside and out. Every two years a deck should be redone, cleaned and sealed. A new cedar deck will not hold as much oil based sealer in that natural oils are still present. Thus, you may need to redo a new cedar deck at the first anniversary of sealing and then go to a 2 year maintenance program. The green you are seeing in mildew.

Bleach destroys the lignin in wood fiber. But bleach has it's place in wood restoration when used wisely. A good wood restoration professional has quite an arsenal of products that are used to fit each wood restoration project.

If you do decide to do the deck yourself, DON'T use alot of pressure, especially on cedar. Remember this, chemicals clean and water rinses.


    Bookmark   September 12, 2005 at 9:06AM
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Reed is right. I would come in at about $900 dollars to do your deck (if it has rails on three sides and three or less steps). If you do it yourself and you mess up the prep (likely for a newbie) You will be right back out there in the spring spraying and scrubbbing and overapplying sealer on top of mold only to have it fail by summer's end again.

If properly maintained your deck could last 20 years+. I've seen people save nickels using bleach cleaners and using subpar sealers.

Stripper is going to cost you $100.. Pre mixed acidic brightener will be another $25..Five gallons of quality sealer will set you back $225. Renting a pressure washer (which you need to strip albeit using a nozzzle to take your pressure way down) will cost you another $125 for two days. Newbie on a deck that size prepare for two 8 hour days in the sun stripping and brightening. Another 2 or three days sealing it.

So now you have $475, at least four full days and you still have no guarantee of results. Ooops did you forget to mask properly? You have three dead plants, brown grass and sealer bonded to your nice siding. Hopefully looking at this will change your mentality. You can't afford NOT to hire a professional.

    Bookmark   September 12, 2005 at 4:58PM
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We have a 13x13 cedar deck that is 4.5 years old. We are having it screened in to make it more usable. The contractor is using the original flooring and railings, which has grayed, and put new posts in and a few railing pieces here and there. I have a home "recipe" for a mildew cleaner, and want to know the best way to seal. I am not power-washing, just letting the chemicals do their thing. I don't expect that the old wood will look new again, although that would be great, but I will really look bad if I don't do anything to the older wood.

    Bookmark   February 6, 2007 at 10:46PM
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I have a brand new mangaris (indonesian mahogany) deck. It's beautiful and I want to keep it that way. What's the *absolute best* treatment/sealer/preservative to put on it.

Considering how much I have invested so far, cost is not a factor...

    Bookmark   July 5, 2007 at 8:27PM
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I have a 1-1/2 year old deck. I had a stain professionally applied last spring and it seems to be holding up. But we get a lot of pine needles from local trees which lodge into the tight grooves the deck. How do I get those out without damaging the deck?

    Bookmark   May 5, 2009 at 10:45PM
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Ok, I've read all postings and need to make a decision between the three finishes that I believe may work on my deck, CWF UV Cedar recommended by handyman, TWP 100 series by john_hyatt and Sikkens SRD by multiple people and my builder. I just had a 630 sqf ceder deck buildt three feet off ground with railings and two sets of steps. I live in Northern MN where we have cold and snow for 6-7 months a year. I've tried most of they other brands on others decks with poor results. My goal is to us as clear a finish as possible that will allow me to re-apply every year or two without having to sand off the old finish. Does anyone have a recommendation or update on the finishes mentioned before I have to make a decision. Thank you.

    Bookmark   July 28, 2009 at 3:19PM
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Do not use CWF. It is a water based acrylic paint. It looks and performs like paint and will require a total stripping refinishing process in a couple of years. It doen not penetrate the wood; just sits on top like paint. (The label claims it penetrates...Bull!) Go with an oil/solvent based product that actually absorbs into the wood, has some pigment, and has strong UV inhibitors.

    Bookmark   July 28, 2009 at 5:21PM
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The JonMon agrees with Aidan. But nuf said on the finish I use.

    Bookmark   July 28, 2009 at 7:43PM
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What opinions if any does everyone have on WOLMANS F&P product? Has anyone used this and what are you results? Thanks, Ron

    Bookmark   March 31, 2010 at 4:05PM
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