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MDO Rips for Ext. Trim?

basswood | Posted in Construction Techniques on August 20, 2005 04:56am

Anyone ever use MDO ripped into 1×6’s or 1×4’s as exterior trim?

I am planning on creating a frame and panel look below a series of windows and was thinking of using 1/2″ MDO for the panels and 3/4 MDO for the frames with small moldings covering the 1/4″ edge of the 3/4 MDO frames.

Whadda ya think?

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Replies

  1. User avater
    basswood | Aug 20, 2005 03:48pm | #1

    bump

  2. dinothecarpenter | Aug 20, 2005 03:59pm | #2

    why not?

    1. Bing187 | Aug 22, 2005 06:34am | #3

      Make sure it's exterior mdo, or it'll blow up to about twice it's original thickness; seen it on a circle top casing I made once. Had scrap "medex"(ext. MDF) picked up scrap int. mdo. by mistake. 

      Very embarassing phone call about a year later.

      Bing

  3. MikeSmith | Aug 22, 2005 06:58am | #4

    bass... we use mostly mdo.. only it's an exterior grade called   GP  PrimeTrim....

    if  it's going to be ground contact we use Azek , or Koma...

    but anything that is going to be painted, not in ground contact... we use the  GPPT

    all the trim in this pic is GPPT...

    we prime all raw edges,  and backprime too

    View Image

     

    Mike Smith Rhode Island : Design / Build / Repair / Restore



    Edited 8/22/2005 12:00 am ET by MikeSmith

    1. User avater
      BillHartmann | Aug 22, 2005 03:39pm | #5

      "bass... we use mostly mdo.. only it's an exterior grade called GP PrimeTrim.."MDO or MDF?

      1. MikeSmith | Aug 22, 2005 07:45pm | #6

        thanks for catching that , bill...

        GP PrimeTrim is, of course , an MDF..

         we use MDO  ( single or double faced ) for interior shelving and cabinets.. but i wouldn't use it for exterior trim..

         MAYBE i would use it for say, victorian gingerbread trim, or other scroll type exterior trim.. like on the rake bargeboards

        Mike Smith Rhode Island : Design / Build / Repair / Restore

        Edited 8/22/2005 12:47 pm ET by MikeSmith

        1. User avater
          BillHartmann | Aug 22, 2005 10:08pm | #7

          Will MDO is all called Sign Board because it used a lot to make signs.But you still have plywood edges that need to be "sealed".

          1. User avater
            basswood | Aug 24, 2005 03:21am | #8

            Bill & ALLPerhaps 1/2" MDO would be Good for the panels and the GP ext. MDF for the frames. I'm considering hanging large pieces of 1/2" MDO and nailing the fames on top. Do the parts of the frame and panel design need to be able to move or is this material stable enough to glue and nail the whole assembly?

      2. AndrewG | Aug 25, 2005 12:17am | #11

        Bill,

        The Georgia Pacific "Primetrim" I used was definatley MDF.

         

        ANdrew

        1. chills1994 | Aug 25, 2005 03:09am | #12

          Just put up a bunch of MDO panels and cedar 1 X's on the exterior of a chain restaurant.  Caulk, caulk, and more caulk.  I think if water settles into the plies of the MDO and can get trapped there it won't take long before it rots.  It was kind of a band aid fix anyway.  The architect should be shot for drawing up those details of exterior wood trim.  Not to mention the cedar sawdust might have given me this cough.  Arrggghh!!!

  4. Shep | Aug 24, 2005 03:46am | #9

    I've used MDO as the base for a panel system like you describe, but with FJ primed pine for the stiles and rails ( Windsor One), since the edge veneers would show.

    If you use an overlay moulding,, I see no problem with using the MDO for the entire job; its an exterior grade plywood, so it should hold up well.

  5. AndrewG | Aug 25, 2005 12:15am | #10

    Basswood,

    I looked into that in the  1990's ands almost did.......then I stumbled onto Georgia Pacific's "PrimeTrim" - an MDF product made with exterior glue, made into 16 foot lengths of 1x6, 1x8 & 1x10. The boards have eased edges and come factory-primed. A rip of 3/4" ext plywood for proper stand-off and the rest was easy. Looks great and is so inexpensive it is hard to believe.

    I worry about the exposed edges of MDO over time a lot.

    'luck,

     

    Andrew

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