I need to replace the deck boards on my 2nd story deck. —The existing deck boards at 7/8 x 4 3/4. I can not purchase this dimension of boards anywhere. The most common deck boards available in my area are 5/4 x 6.

The new deck boards are 3/8 inch taller. How do I deal with the siding directly above the 7/8 deck boards?

See pictures of the existing deck.

Siding meets deck enter image description here enter image description here

  • 1
    Have you measured correctly? It sure looks like a 5/4 deck board that is 1 inch thick will slide in there.
    – RMDman
    May 8, 2023 at 0:14
  • You might be correct! I have to try it with a new board.
    – mykg4orce
    May 8, 2023 at 2:27
  • 1
    Just like a 2x4 is not 2''. A 5/4 deck board is not 1 1/4. It's 1 inch.
    – justin j
    May 8, 2023 at 11:39

1 Answer 1


The new deck boards are not 3/8" taller only 1/8.

5/4 x6 decking is 1" thick and 5 1/2 " wide.

  • And once dried out it could get down to 7/8.
    – justin j
    May 8, 2023 at 11:37
  • Once the PT lumber has been allowed to dry (prior to installation) if that 1/8" is still too much to slip under the J-channel, just run the board through a planer until it will slip in there. The 1/8" from the edge board to the next one is not likely to be a trip hazard, but if you don't like it, plane the next board down to 1/2 the difference between the edge board and the rest - a 1/16" difference in thicknesses between the first 3 boards will definitely not be an issue. You don't have a planer? Find a local woodworker or lumber yard to do it for you.
    – FreeMan
    May 8, 2023 at 17:22
  • Another option would be to mark the clearance needed on one edge of the board then just sand a slope into that board so the side closest to the house is low enough to fit under the J-channel and the other edge of the board is full height. The odds of anyone stepping on the board that close to the house to notice the slope will be very low, as are the odds of anyone putting any sort of furniture that close to the wall.
    – FreeMan
    May 8, 2023 at 17:26
  • Thank you very much. These are the best ideas! I think I will go ahead and use the chamfer option as that will probably be the least noticeable!
    – mykg4orce
    May 10, 2023 at 11:54

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