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I have a higher and lower level decks, attached to each other. Between the decks there was a single-step staircase built as a block attached to deck boards.

I removed those and need to re-do the stairs. I want to do it using small stair stringers. How do I attach them to the lower deck's joists, if I were to space them so that each stringer is right above a joist?

enter image description here

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    TBH, I don’t think stringers are what you want for a single step. Just redo the deck boards and duplicate what was there, taking drainage into account. And check that the upper deck boards aren’t so rotted that they aren’t supported at the rim board. Jun 28, 2023 at 11:50

3 Answers 3

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If you place the stringers directly on the joists, you can toe nail 1 nail ( or screw) in the front of the stringer and scab a piece of PT 2x4 on either side vertically.

Even better but a bit more expensive is to use a mending plate. One on each side will make the stringers strong as you will ever need.

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Even better than placing the stringers directly above a joist is to place them between joists and support them with blocking hung between a pair of joists with joist hangers. Then you can use an appropriately sized bracket to attach the two 2x boards at a 90° angle.

From the top down it would look something like this:

 + Existing Joist
 |
 |       + New Stringer
 |       | 
 |       |       + Existing Joist
 |       |       |
 v       v       v

 ~       ~       ~
| |     | |     | |
| |     | |     | |
| |----+|-|+----| |
| |----+|-|+----| |  < New Blocking
| |     |_|     | |
| |             | |
 ~               ~

Note: The plus sign + indicates metal brackets for attaching the stringer to the blocking.

Some additional notes:

  • Use the same size material for your new blocking as the existing joists (i.e. if you have 2x10 joists, use 2x10 blocking.
  • Use joist hangers sized for the size joists you have
  • For the stringer to blocking brackets, something like this product: enter image description here
    Image courtesy of Lowes.com. No affiliation with the mfgr or retailer, but I've used these with great success.
  • Be sure to properly attach any/all joist hangers by following the manufacturer's instructions (which, for the referenced Simpson Strong-Tie™ product noted above, includes filling all holes in the bracket with the appropriate sized nails/screws).
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  • With the blocking solution wouldn't I need two blocks at 90 degrees to support the stringers at the bottom? Wouldn't the stringers deform the blocking and get deformed themselves with a single blocking piece, sagging slowly over time? Jun 28, 2023 at 17:49
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    No more so than the deck joists themselves. You could double up the blocking (actually makes finding appropriate connectors a bit easier) if you wanted.
    – FreeMan
    Jun 28, 2023 at 23:46
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You really don't need to, at least for structural purposes.

A single stair that wide can't possibly go anywhere, and it doesn't support anything other than itself (assuming adequate attachment at the top), so the only reason to attach at the bottom is for abatement of noise due to bounce vibration.

Just toenail each stringer once to the decking below. Consider predrilling because the short segments of angled grain are highly prone to splitting.


I agree with Aloysius Defenestrate that stringers aren't the right solution unless your goal is to extend the upper deck. Then it's a good strategy, if a lot of extra work. Stringers are putzy. Fit carefully and check thoroughly that you aren't creating a ski jump or downslope, which would be a safety concern and look bad.

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