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  1. #1
    Join Date
    Jun 2004
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    St Louis, Mo for the past 25 years
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    Default spacing for cedar deck boards

    I have a deck replacement coming up and the client wants to use cedar for the floor. wants 2 x 6 boards. I have done those in the past and have always spaced them about a 16 d nail apart. Is that still acceptable? I have done so many composite materials lately that I am now wondering if that is still what most recommend.

    I suppose the best thing would be to do a moisture test on the materials and try to figure out how much it might shrink but I do not have one.

    Advice.

  2. #2
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    Jun 2004
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    sonoma ,calif
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    Default Re: spacing for cedar deck boards

    i have never noticed a difference between rdwd and cedar as for spacing .it was moisture in the boards that was tricky . probable depends on location but a 16p was to small ,I used a 20P for years but seem to be getting bigger lately . a larger spacing[16p vrs 20p] helps to hide the varitions in spacing width as you lay your boards .drains a little better .lately though due to leaves a bit wider spacing has shown to be of value .

  3. #3
    Join Date
    Oct 2007
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    Portland, Oregon
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    1,335

    Default Re: spacing for cedar deck boards

    I use my speed-square as a gauge.
    Tom

    "Whoever ceases to be a student has never been a student." George Iles

  4. #4
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    Sep 2004
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    down the shore
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    Default Re: spacing for cedar deck boards

    I do 3/16 to 1/4". I rip spacers a few inches square the thickness I want, or just use luan, stick a finish nail through them so they don't fall through.

    I like 1/4" for drainage, but it can look a bit too wide for some HO's.

    Never liked the nail. They fall through too easily and can leave a dent when you have to straighten a board.

  5. #5
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    Jun 2004
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    sonoma ,calif
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    Default Re: spacing for cedar deck boards

    i see so many 1/4" and 3/16 spacings on decks these days and they look fine .I have several clients with close boards that are gummed up with sand ,leaves ,dirt and that means rot .i have client who regularly spend hours cleaning out gaps .

  6. #6
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    Jun 2004
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    St Louis, Mo for the past 25 years
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    Default Re: spacing for cedar deck boards

    I may look at the spacing I would get with a speed square. The deck does sit under quite a few trees, on a long needle pine of some sort. I am sure that some spacing would be appreciated to help with debris on the deck.
    I am a little concerned about the boards shrinking some more after installation but it may not be too bad.

  7. #7
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    Washington, DC
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    Default Re: spacing for cedar deck boards

    Speed squares are not all the same thickness!

    And if your boards are not all the same moisture content, (some boards sitting on the top of the pile will be noticeably drier than others), they won't all shrink the same amount.

    Tom
    1) Unconsciously Incompetent: He knows not, and knows not that he knows not. He is a fool. Shun him.
    2) Consciously Incompetent: He knows not, and knows that he knows not. He is simple. Teach him.
    3) Unconsciously Competent: He knows, and knows not that he knows. He is asleep. Wake him.
    4) Consciously Competent: He knows, and knows that he knows. He is wise. Follow him.

    May we all endeavor to progress from not knowing that we know not, to knowing that we know.

  8. #8
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    Default Re: spacing for cedar deck boards

    Quote Originally Posted by TSJHD1 View Post
    Speed squares are not all the same thickness!

    And if your boards are not all the same moisture content, (some boards sitting on the top of the pile will be noticeably drier than others), they won't all shrink the same amount.

    Tom
    I am wondering what you suggest or do on a similar job that you would do?
    even if I had a moisture meter how would I figure out that a board at 17% moisture is going to shrink 1/32 of an inch more than the one at 11% and thus make adjustments as I nail it down.
    that seems over thinking it.

    I believe I will do as I have done in the past and make a determination as to a width that looks good and go for it even if I need to make my own spacers. Plus, once they are installed they will take on some of the moisture that is in the air and do their own shrinking and swelling with each season.

  9. #9
    Join Date
    Jul 2004
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    NOLA
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    4,103

    Default Re: spacing for cedar deck boards

    Beezo, get a speed square that reads M/C.
    Problem solved

  10. #10
    Join Date
    Apr 2008
    Location
    SF Bay Area (East Bay)
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    2,251

    Default Re: spacing for cedar deck boards

    I've never used cedar decking, but I've done enough redwood. Out here it's usually pretty wet unless you're buying a fancy grade.

    TBH I don't usually try to do the math, I just have a sense of how much it's going to shrink (or rarely, swell) based on how heavy the boards are and how wet the center is when I make a couple of initial cuts.

    I usually go for a fat 16th or a shy 1/8th (again, redwood is usually fairly wet out here) and end up with somewhere between 1/8th and 5/32nds after a couple of months. I couldn't tell you how my brain is doing the math, but I guarantee an experienced carpenter like you is doing calculus in your brain way beyond most computers' ability without even realizing it.

    That said, here's a calculator where you can plug in species and m.c. and end up with total shrinkage: http://www.woodweb.com/cgi-bin/calcu...ator=shrinkage

    (The grain orientation has to be entered also- v.g. will shrink about half as much as flat sawn)
    kevin
    Last edited by kfc510; 07-07-2014 at 06:35 AM.
    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” - Upton Sinclair

  11. #11
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    Jun 2004
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    sonoma ,calif
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    Default Re: spacing for cedar deck boards

    due to the boards being different moisture content ,and due to it being a deck i like a bit more space .Though most of the decks i built were in snow country and the space was needed to get rid of melting snow ,it was also nice because the different variations in spacing blended in better .though I primarily used 20p nails then .unless your wood is kiln dried and clear your going to have movement ,your going to also have to fight a few boards to get them close as you can to straight. give yourself a break -it is deck ,subject to a lot year long constant change .

  12. #12
    Join Date
    Sep 2005
    Location
    Washington, DC
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    Default Re: spacing for cedar deck boards

    Quote Originally Posted by m beezo View Post
    even if I had a moisture meter how would I figure out that a board at 17% moisture is going to shrink 1/32 of an inch more than the one at 11% and thus make adjustments as I nail it down.
    that seems over thinking it.
    That's not what I'm talking about.

    Most decking, having come from the same unit, and before that, from the same mill, will already have basically the same MC. But in my experience, many times I have received material that I could tell just by handling each piece, that certain pieces were way different than others. They might not be on the top of the pile once I received it, but I can take an educated guess that those few boards were sitting on the top of the pile that was out in the yard, and that's why they feel a lot drier.

    What do I do? Try to calculate how much less they will shrink?

    No. I just don't use them. But I'm on the lookout for them, because I know it happens.

    Tom
    1) Unconsciously Incompetent: He knows not, and knows not that he knows not. He is a fool. Shun him.
    2) Consciously Incompetent: He knows not, and knows that he knows not. He is simple. Teach him.
    3) Unconsciously Competent: He knows, and knows not that he knows. He is asleep. Wake him.
    4) Consciously Competent: He knows, and knows that he knows. He is wise. Follow him.

    May we all endeavor to progress from not knowing that we know not, to knowing that we know.

  13. #13
    Join Date
    Jun 2004
    Location
    St Louis, Mo for the past 25 years
    Posts
    7,477

    Default Re: spacing for cedar deck boards

    Did the deck and went with a heavy speed square width. Basically used the speed square and just made it a little loose. I know this deck sees lots of leaves and probably worse pine needles which I know will be catching on the tops of the joists. I suggested to the owners that they get some sort of small width screw driver or at least a putty knife and occassionally do a little clean out between the boards if a washing does not push the stuff out. I would not say they are anal but are pretty clean and neat folks so I think they will keep after it and do just fine.

    I did also do a bit wider as I got closer to the house just so water and snow could maybe get off the deck a little quicker and not want to seep back into the house. Probably more like a 3/8 for the first couple of rows.

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