My deck has a diagonal decking. To attach the decking to the ledger side of the deck, 2x4 blocks were screwed directly to the ledger. I'm trying to improve water flow from the ledger. I'd like to move the blocks so that they are as seen in the picture I found below

rotated and staggered

This is what the blocks look like now:

bottom view

top view

In the photo, you can see that there was some sort of filler or something to attempt to seal the space between the block and the ledger. It just doesn't seem like the right way to do it. There the space between the decking boards is so narrow and having this blocking here just makes the distance the water has to travel to escape the ledger flashing longer. Compound it with all the debris that builds up between decking boards and I suspect it is contributing to my water problems.

Will moving the blocks as I described cause too much unsupported overhang of the decking? Is there some other reason I shouldn't move the blocks? Is there some other standard way diagonal decking is fastened on the ledger side of the deck?

2 Answers 2


First off, You mention the water escaping the ledger flashing - it's doesn't look like there's any flashing on that ledger board at all to me. Is that something you were planning to add? (I certainly would if I were you).

As for weakening the decking by moving those blocks back - I wouldn't worry about it. An overhang of an inch or two shouldn't cause any problems.

  • Thanks for your answer. In the pictures, you can only see the shiny edge of a drip flashing which covers the ledger and ends right before the blocking.
    – Jon
    Jul 6, 2017 at 20:05

I ended up using treated 2x6's suspended on joist and saddle hangers. I think this looks nice and allows me to attach the decking an inch or two closer to the wall than the 2x4 method I was considering in my question.

I left space for water to flow between the ledger and the new blocking. As part of this project, I also used a larger drip cap over the ledger and properly integrated that with new 12" flashing and the wrb. (previously, the wrb went behind the drip cap). The aluminum drip cap is protected from corrosion from the treated ledger with a strip of butyl self adhesive flashing. I'll need to fill some holes in the decking now where it used to be attached to the old blocking. Its rained a couple times now and I've been very happy with the way the water has flowed away from the house an past the ledger. View from above without decking

View from underneath without decking

View from underneath with decking

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