Replies

1. 
   tek | Oct 19, 2009 03:56pm | #1

   I've done this in the past kind of like a platform frame. The 4x4 or 4x6 posts go up to a 4x perimeter beam, attach with a post cap, then the next lift sits on the 4x beam with a post cap and on and up from there. The key to a triple decker porch seems to be the diagonal bracing.

2. 
   6bag | Oct 20, 2009 01:22am | #2

   bolted lapped scarf joint.

1. 
   glsstep | Oct 20, 2009 02:26am | #3

   I did think about a long lap joint but thought it may not hold up to a strict Building inspector. I may need to get an engineer to spec out the required technique. That's why they get paid the big $$$.
   Still open to other suggestions that have met building code requirements in the recent past.
   Thanks.

3. 
   KFC | Oct 20, 2009 02:38am | #4

   LSL? LVL? Paralam?
   k

1. 
   glsstep | Oct 20, 2009 03:26am | #5

   I believe those would all be beams and not posts but I could be wrong.
   G.

1. 
   KFC | Oct 20, 2009 04:42am | #6

   You can certainly get Paralam posts. LSL's are commonly used for studs, so I don't know why you couldn't gang up a few, although, I'm not sure of specs. I have doubled up LVL's for vertical loads, with sds or lag screws holding the multiple members and plies together, and it worked great, although, again, I don't know what the load specs would be.
   I'll see what specs I can google up.
   k
   edited to add: I-Level by weyerhauser is showing specs for "Parallam Columns" up to 24' in length. I don't know if you could special order a 30'er. (Dry location too, I don't know if that matters.)

   Edited 10/19/2009 9:51 pm by KFC

1. 
   Clewless1 | Oct 20, 2009 03:19pm | #12

   but not for exposed deck/porch applications, I'm guessing. Never heard of engineered stuff really being used outside. Exception is glue lam beams in some applications.

1. 
   KFC | Oct 20, 2009 05:15pm | #14

   Yeah, I said dry location only in post 7. Depends what he means by porch, I guess. covered? screened? glassed?
   The only true outdoor porches I've seen with 30' columns are the parthenon and funeral parlors.
   k

2. 
   mikeroop | Oct 20, 2009 05:13am | #7

   there most certainly are post made of those thingys.

3. 
   KFC | Oct 20, 2009 05:42am | #8

   More info: there's a table in the I-level web page for tall walls showing load ratings for both 30' LSL's and PSL's, so those lengths are available.
   k

4. 
   dovetail97128 | Oct 20, 2009 05:53am | #9

   Might look into glu-lams as well.
   http://www.timber-technologies.com/index.cfm?event=pageview&contentPieceID=5802

   Life is Good
1. 
   KFC | Oct 20, 2009 07:16am | #10

   Those go up to 40'. Nice add.
   k

1. 
   dovetail97128 | Oct 20, 2009 07:54am | #11

   Well if it were me I would be looking at a steel column and plan on wrapping it.
   Bring it out in sections and site weld it or bolt it together.
   Life is Good

5. 
   Clewless1 | Oct 20, 2009 03:25pm | #13

   How about heavy metal plates e.g. 4x20" that you lag or bolt through from both sides? Still may require engineering. On the other hand, an engineer SHOULD show you the easiest/cheapest way and avoid the overdesign that you might end up with. He's probably done this kind of things a number of times.

   The issue is most likely the unsupported column length that is allowed (i.e. w/out some sort of e.g. cross bracing or intermediate support). Installing this intermediate support is likely the key to extending the length of the column/post. Wherever the support ends up is where you tie your next piece together. So if it is crossbracing, you have a metal connector for both the crossbrace and the next column piece ... all in one. I'm just recalling my structural engineering from college (what I can remember).