Replacing Existing Deck Stairs (First Time DIYer)


Old 06-21-15, 08:24 PM
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Replacing Existing Deck Stairs (First Time DIYer)

We just recently bought a house. The deck appears to have been recently re-done, but whoever did it used the old stairs. From what I'm reading, they are far outside of code for a few reasons; 1) no mid-supports, 2) rise/run exceeds max allowed. My question is what would be the best way to re-design these? Current dimensions are:

Rise: 8-1/2"
Run: 11"
Total Rise: 85-1/4" (from finished patio to finished deck)
Total Run: 96"
Tread Width: 39"

Total of 9 stairs (PLUS top riser flush with deck). I'm kind of OCD in the fact that I want all of the components to be of the same material (same PT wood as the deck). One of the guys at HD that I talked to said I'd be better off using their pre-cut 5-step 7-11 (rise-run). I looked at them, and they were sloppy cuts... I'd prefer to do it myself. I just have no experience with this, and I want to do it right the first time.

My first idea was to do either an 11 or 12 step design (with an 85.25" total rise, would be 7-3/4" or 7-3/32", respectively). My understanding of Building Code is that anything over 5-steps needs supporting; so I would need 2 supports built in, roughly around the 3-4 step range. (Which is another question I had; what's the best way to support mid-span? I'm guessing they make brackets to attach to the top of a 4x4 post to adapt a 2x12 stringer? And I'm thinking the patio slab would suffice for support of the 4x4, using wedge anchors and and brace at the base, no? I'm unsure of slab thickness at that point, but exterior perimeters are over 4" thick at the thinnest point.)

Another idea i had was to make a landing somewhere towards the bottom and open up the width of the stairs to the width of the landing (which, from what I see from Building Code, is required to be 60x60" if stairs change direction). At a later date, I'd like to extend another set of stairs, essentially making it a 'T' instead of an 'L'.

Attached are pictures of the current setup. Any input would be greatly appreciated. I think everything else checks out, but if you notice anything in the pictures that could possibly be a concern, please let me know. Thanks!
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Old 06-24-15, 12:27 AM
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More research and math says that I should go with:

7" rise due to 85-1/4" finish to finish MINUS 1-1/2" '2x4' to make flush with the deck (total of 83-3/4").

That means 12 stairs with a 7" rise.

Stairs are 39" wide; planning on 3 2x12 risers.

More questions:
1) Run: Undetermined (3/4" tread nose), but more than 11". What size lumber, and what gap between them? 2x6 w/ 1/4" gap?

2) Toe kick... required? My wife and I agree it would be better to go without and I cannot find code (in Seattle) that says it's required unless the run is less than 11".
Old 06-24-15, 06:50 AM
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Stair Stringers

I would go with 13 steps. The rise is 6 9/16 in. Reduce the bottom rise by 1.5 in. if you are using 2x treads. 11+ in. tread depth.

Stairs are 39" wide; planning on 3 2x12 risers
Stringers are the saw tooth members supporting the treads.
Old 06-24-15, 04:22 PM
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You may need risers (what you are calling "toekick") because of the 4" sphere rule. R311.7.4.3 (IRC 2009)

You also don't subtract 1 1/2" from your total rise. 12 steps at just under 7 1/8" will get you close to 85 1/4" finish to finish.

You cut that extra 1 1/2" off the bottom of the stringer (also called a stair jack) with a level heel cut once you have the stairs all laid out... otherwise that bottom step would be 1 1/2" taller than all the rest once you put the treads on.

With 3 stringers, two 2x6 for treads would work fine. Cut the stringers so you have the right amount of nosing once your treads and riser are applied.
Old 06-30-15, 09:32 PM
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Stringers are the saw tooth members supporting the treads.
My apologies, I did know that, just not familiar with the terminology in day to day.

More questions:
1) Stringers: With a total rise of 85-1/4" and a run of 11" (x12 steps = total run of 132"), using Pythagorean's Theory, I need stringer lengths of around 13', so 2x12x16' stringers.
Per code, 16" OC; @ 39" width, 3 stringers @ 13" OC.

2) Tread Overhang: I recently read that it's common practice to have 1-1/2" over-hang on each side of the tread on notched stringers. I was not accounting for that, and will interfere with the railing balusters (which I haven't even began designing or researching) if I were to keep it uniform with the deck. Is this necessary?

3) Vertical Supports: Can I 'block' with 4x4s at the bottom and middle with these brackets (Simpson Strong-Tie 12-Gauge Black Powder-Coated E-Z Base-FPBB44 - The Home Depot) and wedge anchors since I'm installing on top of existing slab? Do they make brackets to attach stringers to vertical 4x4 supports, or will I need to build cross-bracing with lumber between the 4x4s?

If I need to build cross-bracing between the uprights, should I just use another 4x4 and these brackets (Simpson Strong-Tie ZMAX Galvanized Post Cap/Base-BC4Z - The Home Depot) to attach those, and then carriage bolts to the stringers? Or is there a better way to support mid-span?

4) Toe-kicks/riser board: Are they normally installed flush to the bottom of the riser to push out the treads for nosing, or at the top of the riser opening to further support the upper tread? If I'm using a 7-1/16" rise with 2x6 treads, what size lumber should I use for toe-kick?

5) End-cut solution: What, if anything, do I need to use at the end of PT boards? I'm reading mixed opinions. I was thinking of picking this up (Wolman 5-gal. CopperCoat Green Below Ground Wood Preservative-1902A - The Home Depot) just to be safe, but is it necessary, or is something better?

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