This question below that someone else asked fits my situation. One of the answers said to use double wedges. What are those? How can I raise the railing slowly so as not to break or crack the existing composite railing?

The original question: How to fix sagging composite deck railing

I have a composite deck (Fiberon boards with a Trex Designer railing system). The guy that built the deck didn't install any of the crush/foot blocks and now the railings are sagging. He's no longer in business, so now I need to try and fix this myself. I found a place online https://www.diyhomecenter.com/trex/transcend-railing-adjustable-footblock.aspx that sells the adjustible foot block, but I don't know if that'd do me any good. How can I install the footblocks now that the deck railing are already in place?

  • A link to the original question you're referring to would be more useful than a copy-paste.
    – brhans
    Jul 19, 2016 at 17:39

2 Answers 2


Since I was the commenter in question ;-)

Doubled wedges are just wedges put point-to-point and driven towards each other - the wedge is one of the basic machines if your history class even touched on those.

I'll be very amused to see alfreema try what alfreema has written. The wedges described there are at a very steep angle and would be quite difficult to make work in practice. Something more like a 1:12 angle works a lot better - if you have a 4 inch gap you need to be a 5 inch gap, you put 3 inches of blocking flat, and drive two 1.5" thick (at the fat end) 12-18" long wedges point to point on top of the blocks.

Felling wedge - image from stihl usa - there are others

If making the wedges daunts you you can buy plastic wedges for felling trees at a logging supply, or you can use cedar shingles or shims, which are sawn with a taper (they are rather soft for some heavy jobs, but would be up to the railing job) - you may need to use a sizable stack of those since each one is quite slim - but you can do that - and they are 16-18" long with less than 1/2" of taper, so the wedge angle is low (which makes it powerful - at least until the force is so great the wood crushes, where a harder wedge would be better.)

  • Haha, yes the wedges in my solution are too steep. You'd need to measure up an inch from the 5" sides and cut that diagonal instead. Too lazy to edit it on my phone though. In principal, that's the free way to go assuming you have a 2x6 scrap.
    – alfreema
    Jul 20, 2016 at 19:37
  • 1
    shims. composite shims. not wood shims they can compress.
    – Alaska Man
    Aug 21, 2016 at 19:47

1) Measure the height of the railing near the post to determine how high it should be.

2) Now take a short length (say 8") of 2x6 and cut the 6" width down to the height that you measured. Let's say it's 5". So now you have a 2x5 that's 8 inches long.

3) Now put a straight edge from one corner of the 2x5, diagonally, to the opposite corner of the 2x5.

4) Cut along the line, and you will have two 5" x 8" x 9.43" triangles of wood, that are 1.5" thick.

Those are your wedges.

Put one just to the right of where you want to put the foot block, and put the other wedge up against it ... start tapping it lightly and slowly and watch your railing come up to level.

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