Stairs & Railings
Pencil & Paper Stringer Layout
Parts Of A Step
Step 1 - Calculate The Rise
- Divide Total Rise By Maximum Riser Height - Before you can begin
calculating your stair stringer layout, you'll need to measure the "total
rise". For stairs that land on the ground, the total rise is the distance
from the ground to the top of the finished floor. Once you know the total
rise, divide this number, by the maximum allowable riser height.
According to International Building Code (IBC), the maximum riser height is 7-3/4".
limit the maximum riser height to 7".)
You don't have to use the maximum allowable riser height. If you look at the Rise
& Run table on the following page, you may elect to use a smaller value for your maximum
allowable riser height. For example, if your knees just aren't what they use
to be, you may elect to reduce the riser height to 6".
- Always Round Up Gives Number Of Risers - For this example, we'll assume the total rise from the ground to the top of
the decking is 53". Since I personally don't like risers any taller than
7", I divide 53" by 7 and get 7.57. Always rounding up gives me
8 risers. At this point, I now know that my steps will have eight risers. By the
way, even if the
total rise had only been 51" and I divided by 7 to get 7.29, I would still
round up to 8 risers.
- Dividing Total Rise By Number Of Risers Gives Riser Height - Now that
we know how many risers the stairs will have, divide the total rise by the
number of risers to get the actual riser height. For my example, I divide 53" by
8 to get
a riser height
Check Point - It's the lower part of the stair stringers, below the
notches, that carries all the weight. It's important to size the
stringers based upon the total stair run, the width of the stairs, the type of
stringer, and the number of stringers. When you get a
we'll help you to select the right size stair stringers for the job.
Step 2 - Calculate The Tread Run
- Determine The Number Of Treads - If you're building stairs that place
the uppermost tread one step down from the deck/floor then the number of
treads is one less than the number of risers. If your stairs have the top tread
level with the deck/floor then the number of treads is equal to the number of
risers. Since the stairs in my example have two or more risers and are over
30" high, by IBC code, I'm required to install a handrail and railing.
Knowing this, I'm going to elect to place the top tread one step down since
this will make it easier to install the handrail - won't require additional
posts to prevent the stair railing from overshooting the deck guardrail. So for this example, I know there are
- Dividing Total Run By Number Of Treads Gives Tread Run - In this example, since
the stairs are used outdoors and extend to the ground, the stairs don't need to have a specific total run.
In this case, a standard tread run
of 10" is selected. This is a good tread run because two 2x6 boards laid side by side
add up to 11" which will give a comfortable 1" nosing. Looking at
the Rise & Run table on the following page, we see that a rise of 6.625" and a tread run
of 10" produces a nice 33.5° stair angle so we're all set; the tread run is
Check Point - The area of the deck where the stairs connect must be reinforced to handle
the weight from the stairs. You don't want the framing to fail
if there is an emergency and a lot of people fill up the stairs. The amount and
type of reinforcing depends on the location where the stairs attach. There are four
different types of reinforcing approaches (depending on whether the stairs
attach to a side or end band joist and whether the joists are cantilevered). When
you get a password, we'll teach you how to add
extra stair reinforcing so your deck is strong enough to support the heaviest of
The content under the "How-To" menu is a small
sampling of all the material covered on BestDeckSite.
For immediate access to in-depth information on Building Codes related to stairs and railings, an on-line
selecting the size of lumber for the stringers, and intermediate landings, as well as, comprehensive
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