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joining boards for deck cap rail

milanuk | Posted in Construction Techniques on November 2, 2005 04:43am

Hello,

I’m finishing off my deck project, pretty much down to the cap rail now. The way this is supposed to work is that the cap rail board runs straight down the top of the handrail, from one end to the corner, meets in the corner at a mitered 45, then goes on to the next corner, and so on. The posts are trimmed flush w/ the rail member underneath, and do not protrude above at all.

I’m looking at what would be the best way to join these boards together… I’d been thinking of putting a 45 angle on the end of each board, and then glueing with a biscuit or spline of some sort in there to keep the boards together, and to avoid having one warp or shrink away from the other leaving a gap. Putting a biscuit in at that particular angle seems a bit… challenging, at least sitting here thinking about it w/ out biscuit joiner and board in hand at the moment.

Any other ideas or suggestions?

TIA,

Monte

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Replies

  1. FastEddie | Nov 02, 2005 05:56am | #1

    I don't see the problem.  Cut a 45 on the end of the board, then cut a biscuit slot on the 45 face by pushing the biscuit joiner face square against the cut face.

     

     

    "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

  2. DougU | Nov 02, 2005 06:03am | #2

    Monte

    If you have a router you can biscuit with it if you get the right bit, save you from buying the bis. jointer.

    My concern would be that cutting treated wood (just assuming your using treated) at a 45 and jointing it you may get shrinkage that will open up the joint.

    Doug

     

  3. dug | Nov 02, 2005 06:40am | #3

    Most of the deck rails that I build are capped with 5/4x6'' syp.I have found that if I make a perfect miter with this stuff it will open up in a few months.Now what I do is cut the joint so it is open at the heel or inside corner by maybe 1/8''. I then hold my ''face nails'' back about 12'' to 16'' and run a screw thru the outside miter angle and explain to the HO that this screw will need to be''checked'' in a few months to close the gap.This is not a perfect setup, but it will look better in a few months than  a tight miter if the HO does their part. Never tried a biscuit...may work if you use the right glue.

    1. milanuk | Nov 02, 2005 07:38am | #4

      Thanks for your help, guys! The wood I'm using for the cap rail is 5/4x6 cedar, no PT stuff. I guess the thing that seemed like it'd be a problem w/ the biscuit (I have a PC557, but haven't used it much) would be whether the blade would extend far enough to make an adequate cut in the angled face, and also registering it against the what little lip there would be on the mitered 45 face... maybe I could make a jig w/ ####small lip on it to register the plate joiner against, and just clamp the board w/ the edge of the miter flush w/ that lip...whaddya think?Thanks,Monte

      1. FastEddie | Nov 02, 2005 03:30pm | #6

        Ok, now I get it.  You're thinking about trying to cut a slot on the 5/4 edge of the board, not on the 6" face.  I think.  That sounds very hard to do accurately.

          

        "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

      2. User avater
        Homewright | Nov 02, 2005 11:43pm | #7

        Cedar will shrink on you as well so I usually plan on the gappage by keeping the joint apart by about 1/8" and either bevelling the edge or rounding it over, whatever treatment I give the entire rail cap.  When the inevitable occurs, they'll be used to seeing the gap already and won't notice the opening up of your original joint.

        The only way I've ever made a miter tight that stayed tight was to do a half lap joint and glue with gorilla glue then nail from the underside.  It's held up to two Georgia winters and one summer.  But that's a lot of work...

  4. storme | Nov 02, 2005 08:30am | #5

    If you cut the joint across and in-cut as well, then when get shrinkage, there will be no visible gap.

  5. User avater
    Thumbnailer | Nov 03, 2005 01:19am | #8

    I'm at the same point on my deck and something you may want to consider is using 2x6 cedar for top rail. It's much more stable and accceptable to biscuit joining. A single 4" screw counter sunk into the least visible side of the corner into the adjoining rail will double lock the joint and can easily concealed with a dowel cap cut flush and sanded.

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