Replies

1. 
   Shep | Feb 18, 2005 01:14am | #1

   no article, but here's one way I've done it.

   You want a 9" finish column, so start by making a column 7-1/2" square. I like to use MDO ( medium density overlay ) plywood for this. Its stable and paints well.  Just butt the joints, and glue and screw everything together.

    I then attach 3/4" stiles to all corners, making sure that the reveal is the same when completed, That means I rip 4 pieces to one width, and 4 more 3/4" wider. You could also miter the corners, and have all the long pieces the same width, but I think that's overkill. 

   I then add the rails ( cross pieces ), fitting them pretty tight and glueing everything. I glue the stiles to the MDO, too.

   Depending on ther look desired, I usually add a moulding on the inside of the panels, something like a base cap or a nose and cove moulding.

   Putty, caulk, and paint, and you're done.

1. 
   Mongo | Feb 18, 2005 07:31pm | #4

   Shep,

   How does the core (exposed from cutting) of MDO hold up to exterior weathering?

   Assuming, of course, primer and two topcoats of paint.

   Does the ply structure look decent, or do the plies telegraph through the paint?

   Thanks, Mongo

1. 
   wysedav | Feb 18, 2005 08:36pm | #5

   Mongo, I'm pretty sure you know the answers to your questions, but I'll bite.

   I Built a column for a lampost (outside), used MEDEX and poly glue, post was built up at bottom with a double layer of Medex.  All joints were caulked and post was painted with several coats of oil based paint.

   Over the last 2 years, the cut sufaces have swelled, and several joints have failed.  I even went back after the first year to fix up damage and repaint but still no help.

   I think MDO (mitered) would have been a beter material selection.  I guess I'll just have to do it over in the next few years.

   Live and learn

   David

1. 
   Mongo | Feb 18, 2005 08:57pm | #6

   Thanks for the feedback.

   I'm contemplating the same thing, but considering using a lock-miter joint and probably epoxy at the corners.

1. 
   wysedav | Feb 18, 2005 09:25pm | #7

   I'll post some pictures, it's pretty depressing.  It's actually a picket fence and light post combo that is failing.  The whole thing is MEDEX so I have a lot of rebuilding to do.  Go with the MDO!

    

   David

2. 
   MikeSmith | Feb 18, 2005 09:41pm | #8

   bill.. here's a 9" column  built-up on a PT 6x6 

   mostly MDO  with some inlay moldings ..

    the base is Koma so it won't absorb any water when the entry paving is installed

   View Image

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

   Edited 2/18/2005 1:42 pm ET by Mike Smith

3. 
   BillW | Feb 18, 2005 10:11pm | #9

   Nice work Mike (as always!) .... just curious ... why didn't you just build the whole thing of Kona ... Bill.

4. 
   MikeSmith | Feb 19, 2005 02:19am | #11

   bill.... on this job the owners opted for Koma on the 2d floor & roof trim...

   and GPPrimeTrim on the first floor..

   theory being , they don't mind painting trim on the ground level.. but they don't want to do a lot of ladder work.. this post and all of the other trim you see is all paintedMike Smith Rhode Island : Design / Build / Repair / Restore

5. 
   BillW | Feb 19, 2005 02:33am | #12

   Hey Mike - I'm totally hooked on the stuff (Azek, actually) ... I'll be doing some square boxes around the base of some columns, and want to use it but is has no structural value, so I'll use MDO (and attach the railings to that)

2. 
   Shep | Feb 19, 2005 02:11am | #10

   The MDO ply is basically an exterior rated ply with a very thin phenolic facing on it- its used extensively in the sign business, and holds up very well outdoors. You don't see ANY plys telegraph thru- its a really smooth face.

1. 
   Mongo | Feb 19, 2005 02:53am | #13

   But what about the CUT edge that is primed, painted, then exposed to weather.

   Does that hold up as well?

   Thanks!

1. 
   Shep | Feb 19, 2005 03:38am | #14

   The way I build them, the edge of the ply is covered by the built-up layer on top of the MDO, so the edge of the ply doesn't even show. The MDO column is basically the skeleton for the final column.

   I've started using some of the composite products for the second layer- like MiraTec trim boards or Koma. I think they're more stable than pine, hold paint well, and are actually pretty reaonably priced. 

2. 
   calvin | Feb 19, 2005 03:39am | #15

   mongo, I think he's covering the cut edge with the stiles of the panel look he's doing.

   But, the cut edges sanded well and painted properly do hold up.

   Back to the panel idea.  I would be concerned with snow/water sitting on the rails and maybe getting behind the rail and keeping the panels moist there.  Even with MDO, I think I would inset the panels and taper the top of the rails to shed water.   Maybe mike can explain his construction of the posts.Remodeling Contractor just outside the Glass City.

   Quittin' Time

3. 
   Shep | Feb 19, 2005 04:06am | #16

   calvin

       I also glue everything I put together, and I run a bead of caulk behind the mouldings to help seal everything, as well as caulk everything after assembly.

   I could be wrong ( it happens occasionally) but I don't think water will be getting in the way I build them.

   I also don't live in an area where there are a lot of high wind and rain problems.

4. 
   Mongo | Feb 19, 2005 04:55am | #17

   Shep, calvin, thnx

5. 
   MikeSmith | Feb 19, 2005 05:15am | #18

   calvin.... all of those panels are lined with 3/4" scotia  ( cove ).. and everything was primed and backprimed and endprimed ..

    then it was caulked.. and two coats finish.. so. i'm not concerned about water getting behind the stiles.. also , the bottom band of Koma has a 45 deg. bevel on the top...

   and the porch entry roof has a generous overhangMike Smith Rhode Island : Design / Build / Repair / Restore

2. 
   Shep | Feb 18, 2005 01:16am | #2

    In my first reply, I assumed a paint-grade column.

   If you want a stain-grade, just use the appropriate plywood for the 7 1/2" column and trim it with the same wood.

3. 
   Manchild | Feb 18, 2005 06:08pm | #3

   You didn't mention if they were going outside. If they are make sure you seal them inside and out. In humid conditions they can rot from the inside out if they aren't sealed well.