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  1. #1
    Join Date
    Sep 2012
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    Default Where to rest porch column -- atop floor, or atop framing

    I've been working on redoing my wrap around porch -- replacing all the framing, getting ready for flooring. As I was cutting off one of the columns I had that uneasy feeling that maybe I was cutting away too much. My plan was to build the framing, install the t&g flooring, and then simply rest the load bearing columns atop the flooring. It occurred to me that maybe I should rest the column directly on the framing, and run the t&g flooring around it. Well -- in two cases I've already pulled the trigger, but I have 7 more to go. Thoughts?

  2. #2
    Join Date
    Jul 2010
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    SoCal
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    Default Re: Where to rest porch column -- atop floor, or atop framing

    The posts should rest on the framing.

  3. #3
    Join Date
    Jan 2010
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    Default Re: Where to rest porch column -- atop floor, or atop framing

    IMO the only time the column resting on anything other than flooring is the occasional porch where a brick or stone pier is brought up to finish floor height, or higher, like a plinth. Otherwise tradition dictates that the column base rests on flooring, and the flooring board make a straight uninterrupted line from end to end as the drip edge. Fitting 2" pieces of short grain floor boards at the edge as separate entities becomes a maintenance nightmare, as they split, do not stay straight, and the whole perimeter is something of a water trap.
    The other way to look at this question is from the framing angle; there indeed should be adequate support under the column so that the load carries through to the supporting foundation below. A column should not stand solely on flooring with air underneath. That will cause the flooring to sag into a dish. So add some blocking; an open box structure is preferable to a thick sandwich of wood, which traps water and leads to premature rot of the flooring. As much support as is needed, but no more than is required.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  4. #4
    Join Date
    Sep 2012
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    Eastern Kansas
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    104

    Default Re: Where to rest porch column -- atop floor, or atop framing

    Appreciate both viewpoints.

    I'm pretty much planning to do it this way -- http://www.finehomebuilding.com/how-...-rim-beam.aspx

    My porch "was" already done - but for some of the reasons noted, and others - it rotted, settled, etc. So I am completely replacing the framing and the flooring. I am supporting the columns, and then doing the retro work, then putting the columns back onto the floor. Like the video, my columns will be nearly directly over the treated post and double rim joists. So the framing is there.

    It does bug me that if (when) the flooring decays, then my column is sitting on that. That is what precipitated the Q about framing vs flooring. Also, should the column be installed in a bracket that sits atop the flooring -- or just directly onto the floor?

    I'm planning treated t&g flooring.

  5. #5
    Join Date
    Dec 2007
    Location
    Tennessee
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    1,381

    Default Re: Where to rest porch column -- atop floor, or atop framing

    The column does NOT rest on the framing. You want to spread the load, not concentrate it. If it was sitting on the framing, you could end up with a 2x6 section holding up a 6x6 post, only one third of the bottom of the post supporting the weight of the roof. You might as well have a 2x6 column.

    You can use a bracket under the column if you want. I use a treated 2x6 5.5" long so that it makes a nice square block to put under the column between the column and the deck. The horizontal grain of this block keeps moisture from wicking up into the bottom of the column. You can frame the bottom of the column with PT 1x4 if you want to hide it.

  6. #6
    Join Date
    Sep 2012
    Location
    Eastern Kansas
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    104

    Default Re: Where to rest porch column -- atop floor, or atop framing

    Quote Originally Posted by keith3267 View Post
    The column does NOT rest on the framing. You want to spread the load, not concentrate it. If it was sitting on the framing, you could end up with a 2x6 section holding up a 6x6 post, only one third of the bottom of the post supporting the weight of the roof. You might as well have a 2x6 column.

    You can use a bracket under the column if you want. I use a treated 2x6 5.5" long so that it makes a nice square block to put under the column between the column and the deck. The horizontal grain of this block keeps moisture from wicking up into the bottom of the column. You can frame the bottom of the column with PT 1x4 if you want to hide it.
    I like the block idea -- though my columns are rough cut cedar and a real 6" x 6". I can use a 2x8 easy enough. So I'll have framing - then flooring -- then the block -- then the column. Your point about the grain direction is good. This will give me some wiggle room with adjusting the column to get a straight header at the porch roof. I can wrap it with trim as you say to hide both the block and possibly the height of the block (I can plane off to custom fit).

    But I was really more concerned about the flooring rotting than the column. I guess I can try to keep a tight seal on the t&g and keep the exposed end grain of the flooring sealed.

  7. #7
    Join Date
    Dec 2007
    Location
    Tennessee
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    Default Re: Where to rest porch column -- atop floor, or atop framing

    Since you are using PT for the floor, I don't think you will have to worry about rot for awhile. I have 6x6 rough cut cedar columns too. The block under them is 5.5 x 5.5 on purpose, it yields a 1/4" of exposed end grain to help the column dry out if it gets wet.

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