Pine is weaker than oak, but...?

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  • radhak
    Veteran Member
    • Apr 2006
    • 3058
    • Miramar, FL
    • Right Tilt 3HP Unisaw

    Pine is weaker than oak, but...?

    Many years ago I had downloaded the details of making a Patio Bench from the BlackNDecker site. That page no longer exists, but thankfully I have the download.

    It looks like this:



    And the internals are like this:




    Now I’m about to build this, pretty much like shown, but for the dimensions.

    Their bench is 21” high, 24” deep, and 48” long.
    Mine will be 23” high, 16” deep, and 43” long.

    You can see the material list in the 2nd picture above.

    I’m going to vary from it slightly – because my shelf is less wide (long) across, I have reduced the width of the face frame - 2” wide instead of 4”.
    Also, the face frame will be in pine, and the ply on the side will be ¾ birch ply.
    Reason is, wife wants it to be painted. And I’ll be d*** if I use oak only to paint it!

    But it’s select pine – no knots or anything, looks great. I’m not dumpster diving here.

    My changes also includes a third stile in the middle, between the two rails, 1 ½ “ wide, to add some strength to the FF.

    The FF is screwed to the 2x4 frame(s), and to the side panels.

    So my question is – while red-oak would have been really strong, will pine be significantly weaker, as in danger of breaking?

    In sum, oak changes to pine, width changes from 4” to 2”. But a stile is added at the center.
    The bulk of the weight is held by the ¾ ply on the sides, I feel.

    Other info :
    This will be placed outside, in the patio, which is fully covered. The bench will fit tighly between two walls and a back wall, so only the front is visible.
    While there’s some exposure to moisture from rain splatter, it’s not direct rain.

    There’s a similar bench there now for the past 10 years, and does not show any extraordinary wear.
    And while it is meant to be sat on, it’s used rarely as a seat, and more to store casual slippers, garden shoes, etc.

    While I have your attention, might as well ask: for abundance of caution I should paint even the sides and the back, right? I have some exterior paint that I'll use for the front and I might as well paint all over.
    It is the mark of an educated mind to be able to entertain a thought without accepting it.
    - Aristotle
  • capncarl
    Veteran Member
    • Jan 2007
    • 3569
    • Leesburg Georgia USA
    • SawStop CTS

    #2
    Paint or seal everything, inside and out. Humidity changes are the problem. Pine is plenty strong. Compare to redwood yard furniture that is one step above balsa and still holds plenty of fat folks and does not break. Pine should be many times stronger than that. If you are worried about the strength just double up on the front frame.
    capncarl

    Comment

    • cwsmith
      Veteran Member
      • Dec 2005
      • 2741
      • NY Southern Tier, USA.
      • BT3100-1

      #3
      A few years ago I built some window seats in our second-floor library... everything is #2 pine!

      The largest window seat is 18-1/2 deep by 65-1/2 wide. I glued up the biscuit-jointed top out of 1 x 10 stock and built a 1-3/4" thick 'torsion-box' support structure for the seated area. Beneath the seat is an open storage shelf for books. My wife and I can both sit there, as we often do when we're looking over some books, or just having an idle chat.

      The seat is fastened to the wall across the back, and while your plan shows that open, you could close it in for similar support. My window seat has vertical support in the middle front as well as at both front corners. I weigh in the neighborhood of 180 lbs now, but was closer to 195 back then. My wife weighs only 85 or less... so, it easily handles close to 300 lbs of us.

      Although it is inside, we have some terrific humidity here in NY, so I painted all surfaces. I also don't like to use screws and bolts; so the entire structure is glued up, except for the four Spax screws used to hold the top surface to the corners of the support structure. There, they are simply fastened, using washers through large holes to allow for wood movement.

      Considering the location you mention, I would definitely make sure every surface is sealed, and especially so on any end pieces.

      The plan I believe is pretty substantial, especially with an extra cross support. If you have doubts, make it four, instead of the planned three you envision.

      I do believe that I have pictures of my structure as it was being built, but I had a drive failure on that computer a few months ago and have had to replace it. I did get most of the files recovered, but I'll have to do some searching.

      Nice project, and I wish you a good time exercising your skills,

      CWS
      Last edited by cwsmith; 10-17-2014, 04:22 PM.
      Think it Through Before You Do!

      Comment

      • cwsmith
        Veteran Member
        • Dec 2005
        • 2741
        • NY Southern Tier, USA.
        • BT3100-1

        #4
        I just looked at your plan again, and I don't like the base support, which appears to be two layers of stock, sandwiched, and laying flat on the ground or patio.

        Here, that would draw a nice haven for insects like spider, silverfish, stink bugs, etc. Down there, I would think it would pose a lot worse problem.

        I would definitely ensure that bottom surface be well sealed, perhaps even redesigned, and have some kind of "feet" to allow for ventilation in order to minimize 'ground rot'. If I were doing it, I'd use maybe some stone tile or something else impervious to moisture at the corners and would get it up off the patio surface.

        Just a suggestion,

        CWS
        Think it Through Before You Do!

        Comment

        • radhak
          Veteran Member
          • Apr 2006
          • 3058
          • Miramar, FL
          • Right Tilt 3HP Unisaw

          #5
          Originally posted by capncarl
          Paint or seal everything, inside and out. Humidity changes are the problem. Pine is plenty strong. Compare to redwood yard furniture that is one step above balsa and still holds plenty of fat folks and does not break. Pine should be many times stronger than that. If you are worried about the strength just double up on the front frame.
          capncarl
          Now that you mention it, our beds are all pine, and are doing fine. I should worry less.

          Originally posted by cwsmith
          A few years ago I built some window seats in our second-floor library... everything is #2 pine!

          ...
          Although it is inside, we have some terrific humidity here in NY, so I painted all surfaces. I also don't like to use screws and bolts; so the entire structure is glued up, except for the four Spax screws used to hold the top surface to the corners of the support structure. There, they are simply fastened, using washers through large holes to allow for wood movement.

          Considering the location you mention, I would definitely make sure every surface is sealed, and especially so on any end pieces.

          ...

          Nice project, and I wish you a good time exercising your skills,

          CWS
          Good points, thanks. I'll make sure to paint everything before assembly, and then give another coat after too.

          Originally posted by cwsmith
          I just looked at your plan again, and I don't like the base support, which appears to be two layers of stock, sandwiched, and laying flat on the ground or patio.

          Here, that would draw a nice haven for insects like spider, silverfish, stink bugs, etc. Down there, I would think it would pose a lot worse problem.

          I would definitely ensure that bottom surface be well sealed, perhaps even redesigned, and have some kind of "feet" to allow for ventilation in order to minimize 'ground rot'. If I were doing it, I'd use maybe some stone tile or something else impervious to moisture at the corners and would get it up off the patio surface.

          Just a suggestion,

          CWS
          Whoa - great point! I gotta rethink this a bit. I was thinking that lower frame, built with 2x4s, which the plan calls 'platform', would give solidity and strength. But if I have to provide other 'feet', I better redesign it...
          It is the mark of an educated mind to be able to entertain a thought without accepting it.
          - Aristotle

          Comment

          • cwsmith
            Veteran Member
            • Dec 2005
            • 2741
            • NY Southern Tier, USA.
            • BT3100-1

            #6
            I've used simple 1 x3 stock for just about all the bases in my library; but, I build them with the 1" wide edge (or side) down against the floor. (For outdoors, I'd probably use 2 x 4 stock in a similar manner.) Basically, it's a simple box with the front and back the full width and the sides being set in between. I cut 45-degree corner supports from 1X stock as this makes for a very stiff support box, while minimizing the floor contact area and structurally the strongest weight support.

            You're not building a super strong support for great weight, so you could rip the 2 x 4 stock down to something like 3" and you'd thus maintain the same base height as in the plan.

            For something like your outdoor area, I'd use some kind of resilient, non absorbing material, or simply "flash" the base. As I recall, you folk's even get termites and carpenter ants which would love to find a nice wood base in contact with the ground or patio surface. Up here, we still have termites but that mostly is a problem with poor foundations, not furniture-like object. But we do have those (and more) insects that I mentioned. (I simply don't like insects invading my living/leisure space and thus try to NOT build them condominiums.)

            CWS
            Last edited by cwsmith; 10-17-2014, 11:19 PM. Reason: Correction to base stock in italics
            Think it Through Before You Do!

            Comment

            • capncarl
              Veteran Member
              • Jan 2007
              • 3569
              • Leesburg Georgia USA
              • SawStop CTS

              #7
              To add to what cwsmith suggests, you can make the bottom boards that have ground exposure out of the new plastic deck wood sold at the big box stores. 1 piece should give the termites heartburn.
              capncarl

              Comment

              • LCHIEN
                Internet Fact Checker
                • Dec 2002
                • 20969
                • Katy, TX, USA.
                • BT3000 vintage 1999

                #8
                Pine and plywood will be plenty strong. Most furniture wood choices is not the the strength of the individual species but for the appearance and cost.

                Hardwoods will be more dent resistant, too.
                Loring in Katy, TX USA
                If your only tool is a hammer, you tend to treat all problems as if they were nails.
                BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

                Comment

                • JimD
                  Veteran Member
                  • Feb 2003
                  • 4187
                  • Lexington, SC.

                  #9
                  I would use pressure treated pine 2x4s for the base. They will take paint well, when dry, and you won't have to worry about moisture damage, insects, or strength.

                  I think pine is plenty strong enough but I don't know if I'd make the face frame half as wide and also of weaker material. A center stile will help a lot but what about using something closer to the 4 inch used with oak (like 3 inch wide). Those boards add a whole lot of deflection resistance - you could use the sagulator calculator to look at both options and the need for a center stile.

                  Comment

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