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Stringer for deck stairs

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  • Stringer for deck stairs

    I am putting stairs on my deck in an area where I don't have much space for the total run but I think that it will work. The deck is an extension of our original deck to allow access to our new (one year old) lean-to fiberglass greenhouse. The deck is only ~18" high at the gate that I built. I originally planned to leave one large step (for me) and basically use the gate for getting supplies and plants, etc into the greenhouse but my wife who is vertically challenged decided that she would like to have stairs suited to her size (5'4") so she can get to that area with a raised planter bed and a small patio at the end of the greenhouse by the stairs rather than walking around the deck or the house to come in from the other direction.

    Even though the deck is 18" at the ground just below the gate I ran a level to the total run of the stairs, (30") and the height at that point is 16" to the concrete driveway.

    I have built about 4 decks with stairs over the past 40 years so each time it is back to square one. So here's what I figured: I would have two steps from the deck with 5 1/4" rise and 15" run (total 30" run. and 16" rise) which would give me adequate clearance to walk around the deck to access the ground level raised planter and the patio area without tripping on the bottom step. The gate is 40" wide so my stairs will match that. I am using 5/4" X 4" cedar decking so I will need a max 16" between stringer - I figure i will have 4 stringers for the 40" wide stairs so that gives me about 13.3" OC for the stringers.

    I found the clips for my carpenters square so that i can do an accurate repeat of each cut and I have marked it on a piece of cardboard that i will use for a template for the first 2" X !0" stringer which i will then use for the template. If I remember and/or understand the process I will shorten the rise on the bottom of the stringer by the thickness of the decking so that I can maintain the 5 1/4". Two of the stringers sit on the end of the concrete driveway so that is the determining point for the total 16" rise and two of the stringers will be put on concrete blocks to match the first two on the concrete driveway.

    I do have a concern that the 2" X 10" is adequate and if I may need 2" X 12". If 2" X 10" is adequate I do have about 8' of that material so I will only have to by another 8" to do the other two stringers. At the risk of sounding overly thrifty I try to keep the amount of unused lumber to a minimum as it tends to stack up. I suppose that I can do two stringers with 2" X !0" and two stringers with 2" X 12", perhaps?

    At the risk of bragging, the 8' x 12' fiberglass lean-to greenhouse is awesome. I installed it last year - with help from a younger stronger handyman, Buzz, who made it work better. it is on an 18" high base built of 4" X 6" PT timbers with rigid foam insulation in the cavity with 30' of 4" perforated drainpipe with elbows connecting them covered with gravel and an 8' standpipe with an inline fan to blow warm air from the upper part of the greenhouse and circulate it thru the pipes and then exhausts low in the greenhouse.. The idea is for the base to collect some heat that will help keep the air temp in the greenhouse warm at night. So far the greenhouse stay about 7-9 degrees F warmer than the lowest outside temp over night ie. 50 degree low outside but 58 degrees F in greenhouse. Tomatoes do better if temp is above 50 degrees F. I've also put three 55 gal drums painted black filed with water to hopefully capture some of the solar heat. I don't plan to heat is in the winter but hopefully the base plus the water drums will keep the temp high enough for cool weather crops like lettuce and to over winter some of my wife's many flower baskets and pots that are all over the yard and deck. We are in Anacortes, WA about 100" from salt water and our temp is more moderate than Seattle or Bellingham

    If anyone has comments concerning use of 2" X 10" vs 2" X 12" stringers (or other comments) please post them.

  • #2
    I like 2x12. When you cut the stringer for that deep of a run (15”) you might not have much stringer left. If the stringer gets to looking skinny you can always sister another 2x12 to each side, and not cut the sisters for steps. 15” seems much for run, it may be uncomfortable climbing the steps, you might want to mock it up with some concrete blocks or something.


    • #3
      Thanks for the reply. I’m going to make a cardboard template to check it out. I was trying to follow a formula of run plus rise = 20 but I think I made it too long. Back to the book to check the numbers. I do this so seldom that it’s easy to screw it up.

      i had thought of using blocks to simulate the two steps with 4 X 6 timber pieces on concrete blocks with the 5 1/4” rise.
      I’ll keep you posted.



      • #4
        I use to have to design a lot of steps/stair. If I remember back that far, 11” run/ 7” rise was the most popular and comfortable to use. A 15” run is uncomfortable for people with short legs and small feet.


        • #5
          I don't have a lot of experience with this - but I used 2x12 stringers when I built my deck 5 years ago, and I'm glad I did. (I believe that I have 12 stairs though.) I remember being extra sure that I got it right, as 2x12s that long are expensive.


          • #6
            2 x 12 is code here in Hawaii.


            • #7
              Thanks guys,

              i did use 2 x 12 and it worked out great. For the 40” wide stairs I used four stringers making the about 13” OC for the 5/4 x 4 boards fit the treads.