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  • stairs

    I'm involved in building a set of stairs. Is there a formula for the angle to mount the tread based on the run and rise of the flight of stairs?

    chasin' the $

  • #2
    There are a lot of variables in building a staircase. I always like to draw it out before I do anything so that I can figure pitch rise and depth giving me the number os stairs. Stairs, I like to be 11 or 12" deep with a rise of 7 or 8 inches. I think code says you can go as high as 9" or as low as 6" both of the latter are uncomfortable to walk up. It is important to have the same rise in each stair, cuz a person going up or down develops a cadence and if you have uneven stairs they become hazardous. It is even recommended that for every 6 feet of height you need a landing, of minimum of 4 feet. I see a lot of staircases that don't, though. I just keep working it in paper until it all lines up...maybe someone has an easier method, and will chime in. 45 degrees is a good angle, but you can go a little more or less, depending on how much room you have.

    Is this for the chickens?


    • #3
      The simplest method is to chalk line the project onto the floor. Give yourself a base line, then a 90 degree line off of one end. This way you can simply measure out your rise and the run, put the steps in perfectly level and even mark out your cuts perfectly. Use the directions Rocky gave you for the steps, he is right on there.
      Mike Sherman
      Shermans Welding


      • #4
        Mike Sherman mentioned the way I also layout stairs. Depending on your application, you will need to keep to code for ADA regulations. Normally the angle will run around 30 to 35 deg.
        Most of our work is for apartments, some new & some replacement. You need keep the spacing between the steps the same. Easier said than done since the rise never seems to be in your favor. Just keep in mind the thickness & depth of the treads when you layout. 10" Jr. Channel works well for the stringers.
        Good Luck, John
        John C


        • #5
          You didn't mention what the staircase was made out of....since you asked the question I assume you will be making it for the chicken plant. For the stairs I have used Grip strut, Diamond plate and cement. You can order Grip-Strut in any length and they will have a weld plate on each end, the diamond stair tread is just that except you can order it to length but it doesn't have any plates, because you weld it directly to the channel or you can put 1/4" angle to weld it to. The cement stair tread has plates molded into the bottom for welding. You may have to paint the stair tread after with NonSkid paint...It'd ne terrible for some one to slip on a gizzard or something.

          Lay your channels 10" or 12" depending on how high this is going, and layout your stairs using a carpenters square with a bar clamped to it to simulate the stair. and mark you stair tread out so that you have left and right exactly the same on both channels. I build mine laying on the front this way the treads will stop and be even on the front. There's probably more that I forgot, but that's the basics.

          Where's it going to go? How high, and wide is it? Who will be using it...These are factors that may change some of what I have said.


          • #6
            If steps are steeper than 30 degrees you go from stair to ladder.


            • #7

              Rocky D, you can get a neat set of doo-dads from Stanley (I think) that clamp on a framing square at whatever point you wish to aid in quick set-up when making multiple marks.


              • #8

                The stairs will run from the ground to a catwalk for the feather meal loadout operator. We're using 10" channel, 2" angle, and 1"x 12" bar grate steps. We put the channel side-by-side during layout to make sure the steps lined up. It's much trickier than I ever imagined...
                chasin' the $


                • #9
                  Rules for stair design

                  2 risers + 1 tread = 25"
                  1 riser + 1 tread = 17" to 18"
                  1 riser multiplied by 1 tread = approx. 75"
                  7" to 7-5/8" rise ideal
                  nosing should be approx. 1-1/4"

                  These rules work for wood stairs, maybe they will be of some help in your project also.


                  • #10
                    Re: square

                    Originally posted by cope
                    Rocky D, you can get a neat set of doo-dads from Stanley (I think) that clamp on a framing square at whatever point you wish to aid in quick set-up when making multiple marks.
                    I've seen those, Cope, and they are pretty nifty...I just couldn't justify the price, since I would only use them once in a great while. I have more than enough junk, now.


                    • #11

                      Rocky D, as I remember, mine weren't expensive, but I've had them for over 30 years and never used them yet, Just never needed to make a set of stairs! These look like hex nuts except they are slotted for the square and have knurled head bolts to clamp it with. Come to think of it, you caould probably make a pair with a couple of nuts and bolts.


                      • #12
                        Michigan building code requirements for commercial stairways are as follows - tread depth = 11" min. (nose to nose) - riser height = 7" max. / 4" min. - handrail required if more than 2 risers or if over 30" above floor - handrail height = 34" to 38" - minimum stair width = 36" - there may be no more than 3/8" difference in the height of the shortest to tallest step - if the riser is solid, a 1" nose shall be provided.

                        Formual for figuring angle of stairs would be to divide rise by run to obtain percent of slope, where 100% = 45 degrees. (thus a 60% slope would be 45 x .6 = 27 degrees)

                        Didn't notice where you were from Mike, your codes may differ, but hopefully this information will assist you.


                        • #13
                          stair project

                          We used a model to get the angles although a few simple trig formulas could have done it. We set the whole thing up on temparary legs to square it out. i'm learning much about good layout.
                          chasin' the $