Wood-Framed Stairs

!A manual for people who want to do it right. !!!!!!!!!!!!!!!!!!!!!!!

I dedicate this to my son, Wil. He is the eternal optimist and the inspiration in my life. (And his mom is pretty cool too!) !Thanks for reading !v/r !Mike

Wood-Framed Stairs !by Mike Morrison!

Copyright (c) 2013 All Rights Reserved

TABLE OF CONTENTSACKNOWLEDGEMENTS 4

DISCLAIMERS 5

INTRODUCTION 6

A LINEAR PROCESS 7

TERMINOLOGY 8

STRINGER 8

BUILDING CODES 8

RISER 8

TREAD 9

FIRE BLOCK 9

THRUST PLATE 9

SPACING LEDGER 10

MEASUREMENT FORMATS 13

Traditional/Imperial: 13

Feet - Inch - Sixteenth: 13

THE STRINGER 14

INTERIOR WOOD-FRAMED STAIRS 15

REQUIRED SITE INFORMATION 16

Floor-to-Floor Height (F2F): 16

Riser Count: 16

Tread Length: 16

ADA REGS 17

TYPICAL STANDARDS (non-ADA) 17

So in review: 17

CONSTRUCTION CALCULATORS 18

-The Construction Master 18

-The Jobber 6 18

-The HP 50g Graphing Calculator 18

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CONSTRUCTION CALCULATORS (continued) 19

-BuildCalc 19

-Rafter Tools + 19

PRACTICAL EXAMPLE #1 - Determining the Riser Height 20

Floor-to-Floor height (F2F): 20

Riser Count: 20

Tread length: 20

RISER CALCULATIONS 20

THE FRAMING SQUARE 21

STEP DIAGONALS 22

NOT ALWAYS 90˚ 23

STRINGER CALCULATIONS FOR LAYOUT 24

LANDINGS 24

WORKSHEET 25

AS-BUILT SECTION VIEW 26

STRINGER MATERIAL SELECTION 27

STRINGER MARKING 28

STRINGER CUTTING 29

STRINGER INSTALLATION SEQUENCE 30

MIDDLE STRINGER SUPPORT 31

FINAL COMPONENT INSTALLATION 32

STAIR TOWER 34

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ACKNOWLEDGEMENTS!I have worked with many great carpenters and architects and have learned much from each. Without naming each and every individual, let me just say that from Texas to Tennessee from Kentucky to Washington state and even in Western Canada, I have seen many different ways that framers have figured out how to build structures to meet or exceed applicable building codes. !And in this world of amazing technologies, it has also been very rewarding to make “friends” on different construction related forums. !My favorite is Contractor Talk (www.contractortalk.com). !There are a great many, very wise and capable, contractors who are exceptional in their trade. When it comes to framing, some of these contractors could teach college-level trigonometry with their knowledge and understanding of the mathematics required in some aspects of wood framed carpentry. !I have been fortunate that I was able to work in a field that I found thoroughly enjoyable. During this time, I have been blessed with a very loving and capable wife who put up with all of the ups and downs inherent in the construction field. She has been amazing! !Finally, I wish to acknowledge my son who is the single most amazing aspect of my life. I hope that someday soon I will be able to spend time sharing with him the things that I have learned about framing and construction. He may never choose this as a profession but it’s always nice to know how to do things like this for yourself and to help your friends. !!!!!!!!!!!!!!!!

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DISCLAIMERS!If anything written in this book conflicts with current or future building codes, then the building codes would obviously supersede the information in this book. !!

!!The concepts and instruction provided in this book is for educational use only. There is no promise of liability by the author or publisher regarding if someone who builds a set of stairs and becomes engaged in any subsequent damage or injury that may result from such is any one’s fault but the person building the stairs. !!Basically, it’s like this. If you think you are capable of constructing something like stairs and you use this manual to make such an attempt, the entire responsibility of that construction endeavor falls on you. !!!!!!!Now with that out of the way let’s get started.

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INTRODUCTION!So you want to build a set of stairs? That’s awesome! You have chosen the right “book/manual” to learn how to do this. !And, it’s FREE! !In the following several pages you will be given all the relevant information to successfully plan and build a wood-framed set of stairs. If you happen to be a beginner, a good practice would be to work through several scenarios on paper before beginning your project. Also, if you have the material and time available, building a mock-up will greatly increase your skill level and understanding of wood-framed stairs. There are also numerous additional resources available online that will help guide you if your project is outside of the specific examples provided here. Check YouTube and Google. !The main focus will be on straight run style stairs. If time allows I will include circular stairs that have direct vertical support under each step. I will not be addressing curved or circular stairs that are freestanding since the mastery of that skill-level is extremely complex and one that I don’t think I could adequately explain in written words. !Now, this is by no means the final authority on wood-framed stair construction. The focus is building things out of wood in a manner that is extremely sound and strong. I have always stopped and considered everything that I build and ask myself, ‘is there a better way’, under those two conditions? !Also, never build anything to “just meet” or “just pass” applicable building codes. !

ALWAYS build to exceed the minimum applicable building codes. !For the small amount of time and money that it takes to build to this level, I believe that it is completely worth it. !Don’t feel like you have to do things exactly the way shown in this manual. This book captures a successful way to build stairs. Take the parts that work for you and use them. If you have developed techniques that aren’t covered here, please let me know and your methods will be included in future releases. !If you have questions or suggestions about this manual or framing in general, feel free contact me by email at wallmaxx@gmail.com. Depending on how busy I am I will do my best to reply to every inquiry promptly. !There will be those who will not agree with the level of overbuild that is presented within. Everyone is entitled to an opinion, even if those opinions come from hacks. (That’s a joke)

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A LINEAR PROCESS !The process in this manual will be linear from design through project completion. !Additionally, we will work with some terms that explain the components we will be working with. Most will be standard industry terms. Some may be more regionally specific but I will attempt to include enough pictures so that the reader will not be too confused. !So if you are like me, and lists make you happy, here’s one about what we just talked about: !• understanding the terminology used in defining stair components • understanding different measurement formats used in this manual and the industry • understanding how the stairs are designed on paper • understanding the different aspects of stair calculations with a calculator • understanding the required physical site information necessary to perform proper

calculations (stairwell opening, floor/stair coverings, platforms, etc.) • performing accurate calculations • transferring calculated information on to the material to be fabricated • understanding the proper installation sequence of all the stair components • enjoying the satisfaction of a job very well done !Also included is a worksheet and a section view as-built drawing. Let me know what you think of the worksheet. I will entertain any good suggestions to modify it to make it better for everyone. !Building stairs is actually very simple. That’s why I chose to write about it. There are more complex things to build when framing a structure. I will address those as time permits in the future writings. !Once someone grasps the idea and concepts for stair construction, it will become second nature whenever a stair building task is before them. !

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TERMINOLOGY!It is assumed that the reader (you) already possess a somewhat thorough understanding of the terminologies used in the carpentry field. However, if that is not the case, the following terms are included for use as a unified reference as they relate to the parts and fabrication of a stairway. !STRINGER The diagonal structural component of the stairs that is typically cut from 2 x 12’s or LVL (Laminated Veneer Lumber) material. !!!!!BUILDING CODES The riser height and tread length are strictly regulated and inspected. Also things like the

total maximum number of steps in a single run are posted (22), then there must be a landing. These are just a few of the many requirements in code-compliant stair building. !! !!!!!!!!!!!

RISER The single unit of rise per step. This is determined by dividing the total rise height by the number of steps. This value typically falls nearest to 7 5/8” but is in a range from 6 ¾” per riser to 7 ¾” per riser.

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TREAD The single unit of run per step. This is the part that you actually step on on each step. This is usually given in the plans, by the designer. This value typically is between 10” and 11”. In some cases, treads have been made less than 10” and are difficult to safely transit. These are no longer allowed by code. !!FIRE BLOCK Solid draft stopping is typically required in the stud bays of all the walls that are part of the stairwell. Their length is determined in the Construction Master calculator as follows: !

• Stud bay width [INCH][RUN] stair pitch in degrees [PITCH] press [DIAG] !

They are then cut long of a bevel to short of a bevel (I used job-site short-hand = L2S) using the stair pitch in degrees. Each block is installed parallel to the bottom edge of the stringer. !!THRUST PLATE This is a 2x4 plate that is fastened securely to the lower floor system that is to resist the horizontal “sliding” pressure that is exerted by the stringers. It helps to “lock-in” the stringers. At the bottom of the stringer is notched out sufficient wood to allow for the thrustplate to fit correctly.

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SPACING LEDGER Is a 2x4 or sometimes a 1x4 that is sandwiched in between the stringer and the wall. It allows for the drywall and a skirt board to be easily installed, leaving a ¼” final gap on each side of the treads. It is best to glue and nail this to the wall first, then glue and nail your wall stringers to this ledger. This ledger should follow the bottom edge of the stringer as well as the fire blocks. !Dry fit the stringer to the stairwell and trace the bottom edge of the stringer along the 1 1/2” edge of the stairwell studs. This gives the proper location to install the fire blocks and spacing ledger. !It’s not required to enable a proper fire stop, but it is not a bad idea to “split” the fire blocks along the reference line to act as a sheet rock nailer and also for nailing the spacing ledger into. !!ANCHOR LEDGER Some architects draw / require that the top of the stringer be notched in a way to rest on a horizontally installed 2x4 ledger (apparently similar to the thrust plate). !This appears to be an additional consideration that does not bear out any real structural significance. JMHO. !In the following pages you will be shown a method to fabricate and install wooden frame stairs using a method that will ensure a structurally sound finished product. !!!!

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PRESSURE BLOCK This is the way to add shear nailing prior to the introduction of metal fasteners. !

•Install the first wall side stringer. •Cut a 2x8 or 2x10 block the length of the space between the first and second stringer. •Glue and nail it up tight to the first stringer, at the top of the stairs (into the header). •When installing the second stringer, glue, toe and face nail it into the header and the pressure block. !!

In the photo above, the plans called for a Simpson A35 clip to be installed from stringer to header first, thus the gap between the pressure block and the stringer is because the A35 clip is in the way of the block being pressed tightly against the stringer. !!NOSING Nosing is the part of the tread that sticks past the riser once everything is installed. Typically this can be from 0” to 1 1/4”. Nosing makes the stairs feel more “natural” when walked on, because they provide a small amount of tread extension to allow the foot to not have to get too close to the riser.

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PHYSICAL CONSIDERATIONS!It is imperative to follow the approved plans. Any physical condition at the stairwell location that causes an issue with following the plans must be elevated to the proper authorities. !Study the approved set of plans for your project. Look for section views of the stairs; finished floor to floor heights; joist and sub-flooring types. It is critical to make sure that whatever floor surface covering and stair coverings are taken into consideration so that the finished product has as near as exactly the same riser height from finished floor to finish floor regardless of surface type change. !A common mistake made by architects and designers is that they don’t draw the section views to the actual “real-world” sizes using the actual material sizes. !For example, an architect will draw a section view of a wall and call out the height of the wall to be 8’. Actually, that wall will be the total height of the thickness of 3 plates (3 x 1 ½”) plus a stud, in our region (7’-8 5/8”) for a total of 8’-1 1/8”. That 1 1/8” difference

means that you can’t pre-cut your project from using the architect plans alone. !Ensure that the stairwell (the hole framed in the floor system) is in the correct location and is the correct size. Determine if the treads are going to be real hardwood, synthetic wood, or OSB or 2x’s treads with carpet on top. !Finally, also check to make sure that any framing directly above the stairwell allows for the proper amount of headroom clearance. As of the writing of this manual that vertical measurement is 6’-8” or greater. !!

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Notice that the plan above calls for the treads to be 9.5”. This was typical in Memphis, TN up through 2006. Out of over 60+ sets of stairs that I have built over the decades, this was the only place I had ever been told to build stairs with such short treads. !Also, notice that the F2F height is written as 9’-11 1/2”. These homes were all framed as follows: 104 5/8” studs + 3 plates (4 1/2”) + 2x12 joists (11 1/4”) + 3/4” plywood T&G subfloor for a grand total of 10’-1 1/8”. That’s a difference of 1 5/8”. If you were to build this off-site, according to the plans, it would be wrong.

MEASUREMENT FORMATS!Depending on which method is easier to enter, I will be using two different formats for measurements. I will not be using metric. !!Traditional/Imperial: I will mostly try to use the traditional imperial system that is common to American carpenters. It will look like this: 10’-1 1/8” (that would read ten foot one and one eighth inch). !!Feet - Inch - Sixteenth: Truss companies often send their documentation with dimensions listed in F-I-S. It will look like this: 10-1-2 (that would read ten foot one and two sixteenths) FYSA 2/16” = 1/8”. !! !

The reason why I often choose to use the F-I-S method is that it is what I have developed for use in my HP 50g scientific calculator. Also it’s less numbers of strokes to input in a calculator and/or write on building material than the traditional imperial method. You will see that after a while of working with this method is very easy. !Finally, because I may wish to draw some of these things using a CAD program, I will take the calculations to what might appear to be an extreme number of decimal places or to an absolute value. This level of measurement accuracy helps to maintain drawing accuracy during CAD work like when using multiple offset or other sequential movement commands for example. If you are offsetting a series of lines 16 times and you are 1/16” off from exact, then you will be 1” off at the 16th line. !!!!!

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16THS1 = 1/162 = 1/83 = 3/164 = 1/45 = 5/166 = 3/87 = 7/168 = 1/29 = 9/16

10 = 5/811 = 11/1612 = 3/413 = 13/1614 = 7/815 = 15/16

F-I-S7-5-10

STANDARD7'-5 10/16"

THE STRINGER!Stairs are made up of several components, the most important being the stringer. It is the stringer that we will be focusing on with our calculations so that it will be cut correctly. The remaining components typically just need to be cut to length and installed correctly. !Wood-framed stairs are either going to exist inside or outside of a structure. This environmental considerations will dictate the types of materials and fasteners that you will use. The method for calculating how to fabricate the stringer is the same for both and only the exposure conditions are the only real difference between the two. !

!!

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INTERIOR WOOD-FRAMED STAIRS!Starting with interior wood-framed stairs it is assumed that they will never be exposed to water for any length of time except possibly during the initial framing of the structure. Once the structure is dried in, the stairway and all of its components should remain dry. !Nominal 2x12s, LVL, or other structural members may be used for stringers. Stringers are sloped load-bearing members (like joists or beams). Some places allow 2x10 stringers. Why compromise on the strength of the stairs just to save less than $50? Don’t compromise. Don’t use 2x10s. There is nothing that says “cheap builder” faster than springy stairs or other less solid aspects of a home. !Typically, the plans will have some design reference regarding any stairs since they are a code enforced feature that has local,state and federal regulations governing their fabrication and they are inspected as part of the final framing inspection. !Do not cut corners to try to “git r done” when you are building stairs. !

The method that you will learn in the following pages will ensure that your stairs will exceed all current building codes.

!Never just try to meet the required codes. Aim to exceed them. Use good material and proper fasteners as well as thoughtful technique so that the stairs you build will never fail due to your failure to plan and execute correctly. !

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REQUIRED SITE INFORMATION!Floor-to-Floor Height (F2F):

The vertical distance between the top of the finished floor elevation of the first floor to the top of the finished floor elevation of the next floor. What this means is you want an evenly distributed number of segments, called risers, between the finished surface of each of the floors. Any deviations can become a trip hazard. This can be an odd or even number of risers. !

Now might be a good time to point out that measuring the vertical floor to floor height is not done from the top of the stairwell opening straight down to the floor beneath it. Unless the floor at the bottom is completely level, you will need to measure from a line that extends horizontally from the top of the opening down to where the

bottom of the stringers will be sitting. This becomes especially important when building stairs that are attached to a deck and the terrain slopes. Make sure that your measurement is from the point of the ground where the stringers sit, vertically to a truly horizontal line that represents the top of the finished floor. !Riser Count:

The number of risers required to satisfy the code requirements as directed for individual riser height to transit the vertical distance. !

Tread Length:The individual tread length. Sometimes you will be given a horizontal distance that the stairway is supposed to be constructed within. It is rare that you will have to cut a non-inch standard tread length, but if that is required that method will also be explained. Typically trends are between 10” to 12” long.

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ADA REGS!Finally, on July 26, 1990, the federal government passed the Americans with Disabilities Act (ADA) under Bush 41  . If you are building a set of stairs that must be ADA compliant, 1

the riser and tread length are governed by this federal regulation. !If these requirements are part of your project, become thoroughly familiar with them since they can change over time with code updates and amendments. !TYPICAL STANDARDS (non-ADA)!The target ratio currently is for the riser to be near 7 5/8” and the tread to be around 10”. This is of course only a guide and not a mandatory set of measurements. If your Floor-to-Floor height does not evenly divide into 7 5/8” risers, then any remainder would become a trip hazard or you would have to install the stairs in an out-of-proper angle. This would result in the treads no longer being horizontal but having a slope which is also wrong. !Sometimes the best method to confirm the plans, or if not given in the plans, to determine the proper number of risers is to take the Floor-to-Floor height and divide it by the ADA maximum riser standard. This would give you the maximum number of risers for the given vertical distance. Typically there will be a remainder so you would round up to the next whole number and then divide the vertical distance by that whole number to get the exact riser length. Then take the next number lower and divide that into the total vertical height to get the riser height for one less riser. You can continue this until you reach a riser height that exceeds 7 7/8”. As of this writing, risers are not allowed to be taller than this. !So in review:

• Take the Floor-to-Floor (F2F) height and divide it by 6 ⅞” (7” as of 2010). • Round up the answer to the next whole number.

• This will be the maximum Riser Count. • Divide the F2F height by the Riser Count.

• This will be the actual riser height of each riser for ADA compliant stairs. • Subtract 1 from the Riser Count and divide it into the F2F height.

• This will be a good typical riser height (non-ADA compliant). • Subtract 2 from the Riser Count and divide this into the F2F height.

• This will be typically the maximum height of a riser allowed by code. !We will run through this mathematically on the following pages.

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� http://en.wikipedia.org/wiki/Americans_with_Disabilities_Act_of_19901

CONSTRUCTION CALCULATORS!It will be helpful if you have a construction calculator. I have tried the following: ! -The Construction Master from Calculated Industries http://www.calculated.com Amazon Direct Link here

-The Jobber 6 from Jobber Instruments http://www.jobbercalculator.com Amazon Direct Link here

-The HP 50g Graphing Calculator

This is a very powerful scientific calculator and it is my personal preference since I have been able to write custom equations that “prompt” the user to input the proper numerical information without having to memorize the steps necessary to perform the calculations. It operates in RPN, Textbook and Algebraic formats. !Note: It does NOT come pre-loaded with any construction equations. You will need to come up with your own and write them yourself. Amazon Direct Link here !!

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CONSTRUCTION CALCULATORS (continued)!Finally there are even apps for “smart” phones. I have tried most. Here are two excellent ones: ! -BuildCalc from Ben http://buildcalc.com !!!!!!!!!!!!!!!! -Rafter Tools + from SBE Builders www.sbebuilders.com !!!!!!!!!!!!!!Choose something that works for you.

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PRACTICAL EXAMPLE #1 - Determining the Riser Height!Floor-to-Floor height (F2F):

• 8’-11 3/4” (non-typical 8’ foot stud at 7’-9” [plans called for a precision cut, non-standard stud length] + 3 plates + 9.5” I-joists + 3/4” subfloor)

• 8-11-12 (F-I-S) !Riser Count: 8’-11 3/4” divided by 6 7/8” (ADA max) = 15.6727 Rounded to the next higher whole number equals 16 risers for ADA compliant stairs. !Tread length:

• 10” • 0-10-0 (F-I-S) !

The first thing to do is to see if the ADA requirement is necessary for this project. If it is not a requirement then perform the calculations using one and two less risers so that your stairs become one and then two tread lengths shorter with each reduction of a riser up to the point where the risers are no taller than 7 7/8”. This will give you options for consideration in the number of risers/treads (thus the “steepness” of the stairs) if you have the freedom to make that call. !!RISER CALCULATIONS!Dividing the F2F height by the number of risers results in the individual riser height shown: ! ADA: 16 risers @0-6-12 (6 3/4”) ADA COMPLIANT TYP: 15 risers @0-7-3 (7 3/16”) TYP CODE COMPLIANT MAX: 14 risers @0-7-11 (7 11/16”) TYP CODE COMPLIANT NOPE: 13 risers @0-8-5 (8 5/16”) NOT CODE COMPLIANT For the example project in this manual we will not be building it in compliance with ADA regulations. Therefore, our risers will be 7 11/16”” tall and our treads will be 10” in length. !At this point, you have enough information to trace out a pattern on whatever material you will be using for the stringer. However, there are additional steps that we will discuss at this point that will increase your accuracy and are worth considering. !!!

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27 is a repeating set of numbers

THE FRAMING SQUARE !The parts that we are going to cut out of the stringer, end up being a square connection between the riser and tread. The result

creates what looks like sawtooth cuts on the stringer. This is where it is valuable to have a set of framing square nuts to attach to your framing square in such a manner that the outside 90° edge of the framing square can be traced out with the result of an 10” tread and a 7 11/16” riser (or whatever your specific riser and tread lengths calculate out to be). !

Now, when you are tracing the outside edge of a framing square, there is the possibility that you will introduce scribing errors based on the thickness of the lines and how accurately the framing square nuts

are seated against the stringer member. If you use a fat pencil or sharpie you will introduce errors that will compound themselves so that by

the time you get to the end of the stringer you will have created lines that are no longer correctly located on the stringer. A way to prevent this error is to mark the stringer material prior to the tracing with a series of diagonal measurements of each step. This will allow you to have a “check point” to reset your framing square prior to each step being traced. !The framing square is much more than just a 90° tool. In a future manual we will cover some of the “magic” that can be performed when using framing square. If

you wish to learn about the capabilities of a framing square, go to http://chappellsquare.com !

When attaching the framing nuts to the framing square I find it useful to test their location accuracy on something that has a very straight and square edge such as a 4 foot level or the factory edge of a piece of plywood. !

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STEP DIAGONALS!The method for marking diagonals simply requires calculating the hypotenuse or diagonal of the tread and riser. With this length you just sequentially add this length to itself for the entire length of the stringer. !I prefer to use the scientific calculator because it will perform repetitive steps with complete accuracy (removing the possibility of erroneous data entry due to pressing the wrong buttons during the calculation process - fat fingering). In addition to determining the diagonals, sequentially, you are also able to determine the length of the fire blocking that will be installed parallel to the bottom edge of the stringer in each stud bay. We will discuss this later in the manual. !The calculated diagonal numbers are as follows: ! DIAG = √((F2F/Riser Count)2 + (Tread Length)2 = √(7.6964285712 + 102) = √159.235012755 = 12.6188356339 = 12 5/8”   2

!This information also informs you that your stringer will need to be cut out of material that is 14’ long or longer. Typically the ends of a 2 x 12 are split and so being this close to a full-size board you would probably want to go to the next full-size...16’. !Now that you have the diagonals marked on the stringer material, you can trace out steps, and use the diagonals to keep yourself in check. !!!

The image to the left shows a CAD layout for Step Diagonals. !This information can be determined in many ways. CAD and calculators provide the most accurate means.

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Step Diagonals

1-0-10! 2-1-4! 3-1-14! 4-2-8! 5-3-2! 6-3-11! 7-4-5!

8-4-15! 9-5-9!10-6-3!11-6-13!12-7-7!13-8-1!

� It is important to use the most precise value when sequentially adding step diagonals and not use the rounded off value. 12 5/8” is actually 12.625 2

and it is 0.0061643661” more than exact. Using the less accurate number will result in the diagonals being off at the end of the stringer.

NOT ALWAYS 90˚ !Although most stringers have steps that are 90° from tread to riser planes, there are instances where the riser may be sloped as part of the inclusion of the nosing. !When this happens you will not be able to use a framing square easily. For this application it will be best for you to create a pattern from some plywood or other material. !This is a rare type of stairs to be made with wood. Sloped nosing is more commonly found in concrete stairs.

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STRINGER CALCULATIONS FOR LAYOUT!We can now calculate all the relevant lengths required for us to successfully build the components of a roughed-in, wood-framed set of stairs. !

Use the worksheet included on the following page to write down all your calculated numbers. !This is where you need to be as accurate as possible. If you step off with a number that is already rounded off you will end up with an incorrect final product. !Most calculators will show you the rounded off number but they will maintain a several digit decimal point in their memory for calculation purposes. !Try different methods to achieve different lengths. You may even develop your own technique to maintain calculated accuracy. !

LANDINGS !Another reason to write out all of the finished tread elevations is that when the plans call for a landing to be built at a certain step then it is relatively easy to find that elevation in your list and build the landing down from that finished height. !Using the example above, if the plan called for a U-turn landing at Step 7, then the finished height of the platform would be 4-5-14 from a horizontal line that extends from the bottom of where the stringers make contact with the lower floor. !I have included a graphic showing multiple landings and coatings in the back of the book. It will help you to understand some of the many considerations involved in complex stair building projects. !!

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WORKSHEET

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AS-BUILT SECTION VIEW

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STRINGER MATERIAL SELECTION !When considering material to be used in a set of stairs, always choose the most structurally sound members. Additionally, try to select material that is straight as opposed to being crowned. Often times if you trace out a stringer along the top edge of a crowned 2x12 the act of removing the triangular-shaped scrap pieces causes the 2x12 to lose its crown which will result in it not being the same dimensionally as when you originally laid it out. !This is where engineered lumber such as LVL’s are an excellent choice for stringer fabrication. !!

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STRINGER MARKING !Start by marking off the step diagonals. If your material is long enough try to adjust your layout so that if there are knots or other imperfections that you might be able to cut them out. !Never use material that already has serious structural defects in it. Take the best material that you have available and prioritize the best single member as the center stringer and any lesser quality members as the outside members. Typically stairs will be installed with the outside members being attached to walls so that mitigates any minimal structure weakness in those stringers. For freestanding stairs, it is essential to have structurally sound stringers, thus LVL’s are an excellent choice. !Once the step diagonals are marked And your framing square is correctly set up with the framing square nuts attached, trace out the parts that you will be removing from the

stringer. !Use the thinnest/appropriate drawing instrument (a waterproof pen often works well) to draw your cut-lines. !Number the outside tip of each step so that you will be able to correctly identify how many that you need to have when you actually cut the stringer. !!!!

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STRINGER CUTTING !It’s a good policy to always dry fit your stringer prior to completely cutting it and any others. !When dry fitting a stringer, cut the 90° cuts at the bottom of step 1 and at the top (of which ever number that happens to be) before you cut all of the steps out of the entire stringer. !Then take this unfinished stringer into the building and set it where it will eventually be going to make sure that it is the correct length and that the steps that are drawn on the stringer are actually sitting horizontally. !This is a quick way to make sure that you have marked the stringer correctly and that all your calculations are correct and that the stringer will work before you take the time to cut out all the steps. !If everything fits correctly, then cut out all of the steps that you have drawn on the stringer. !Look down the uncut side of the stringer to see if the crown has changed after you have cut all the steps out. When using the stringer as a pattern to trace out the other stringers, flush the uncut side of this stringer with the similarly crowned bottom edge of the additional members that you will be cutting as stringers and tack them together so they don’t move while you are tracing. !The reason why you want to flush the bottom edges of the stringer for tracing is that it will force all the stringer materials to end up being cut exactly the same in depth regardless of how wide the original material is. For example you will be able to use 2x12s that vary from 11 1/2” down to 11” and once they are all cut the steps will all be the same relative distance from the uncut edge of each stringer. Then when these are installed, they will all plane the same across the bottom and top so that the steps and risers will work correctly as well as any applied veneer such as sheet rock across the bottom edge.

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!STRINGER INSTALLATION SEQUENCE!Prior to installation is a good time to take one of your finished stringers and trace out 2 @ 2x4’s and 2 @ 2x6’s that have the same length along the uncut edge from the plumb cut to the seat of the stringer. The 2x4‘s will be used as spacer ledgers nailed along the stairwell walls (if that’s how your stairwell whole exists). The 2 @ 2x6’s will be glued and nailed, flush, along the bottom edge of the middle (structurally strongest) stringer to add additional load-bearing support. !During the dry fit is when it’s efficient, if the stringer is cut correctly, to temporarily tack it in place and scribe the bottom edge along the studs of the wall or walls that make up the stairwell. This line will be used as a reference so that the fire blocks can be correctly put in between each stud as well as the spacing ledger. !

Although not required to maintain a compliant fire stop, it is a good practice when installing the fire blocks, to try to install them with the stringer line being along the centerline of the fire block. This will allow 3/4” of block to act as a sheet rock nailer below the stringer-line and 3/4” of the fire block to be available to nail the spacing ledger into if necessary. !Apply glue to each stud for about 2 to 3 inches above the trace line on each stud and the fire blocks then nail the 2x4 spacing ledgers to the studs and the fire blocks

with the bottom edge of the ledger flush to the trace line. !Some people will argue that it is better to nail the spacing ledgers to the bottom of the outside stringers first and then toenail through the studs into the spacing ledger during the installation of the stringers. Structurally, a face nail is always stronger than a toenail for shear load applications. !Apply glue to the face of the spacing ledger, and install the first stringer nailing it into the ledger and into the header at the top and into the thrust plate at the bottom. !Apply glue prior to every piece of lumber that you will be attaching.

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!Cut and install a pressure block into the header at the top, tight against the first stringer. Take into consideration the 2 x 6s attached to the center stringer. you may have to cut them back an inch and a half in length at the top so that they are not competing for space with the pressure block. !Install the second stringer nailing it into the header and thrust plate. !Install a second pressure block, Again adding sufficient construction adhesive where all the wood components meet so as to make a solid structure that will not squeak or move. !Finally, slide in the final stringer and nail it in place. !!MIDDLE STRINGER SUPPORT !To increase the strength of the middle stringer, you can add two 2x6s to it as shown. Additionally, some stairwells get used for under stair storage and a knee-wall is installed to create a stop. This also greatly increases the strength of the stairs by shortening the actual clear span distance. ! !!!!

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Note: These stairs are going to have hardwood (oak) treads and risers added later, so temporary treads were screwed in place until that time

FINAL COMPONENT INSTALLATION !Once the stringers are installed, measure over both outside stringers at the header to get a baseline measurement for cutting the treads and risers. There may be additional coordinations required to ensure that these 2 items are the right amount of distance away from where the finished sheet rock will be, depending on how the stairway will be trimmed out. !For example, if no skirt board is being installed as a final trim piece, then sometimes it is expected that the treads and risers be cut and installed with only 3/4” space from the framing to where they begin. This leaves a 1/4” space between the finished sheet rock and the stair tread/riser framing. If carpet is going on the stairs, typically they will be installing it tight to the sheet rock. !On nicer homes, trim carpenters will typically install a 3/4” skirt board against the sheet rock. When this is the final condition, then measure and cut the treads and risers to match the over-both measurement of the outermost stringers measured at the header. !!Typically it is the best practice to install all of the risers on to the stringers first. Also, it helps to start midway up the stairs and work your way up and down from there. That way if there is a crown or sag in the middle stringer, it is easiest to work it out starting in the middle of the stringer. GLUE EVERYTHING! !You also have people say that it is not necessary to use 2x material for the risers. Many track homes and cheap contractors will use ripped plywood or 3/4” wood in this application. Every riser acts as a single beam so using 2x lumber for the risers makes the entire set of stairs stronger. !Once the risers are installed, do the treads. !I mostly use HDG (Hot Dipped Galvanized) nails for all my framing and they hold exceptionally well, but some may use to screw the treads instead. !!

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PRACTICAL EXAMPLE # 2 !F2F = 11-1-8 = (10’ walls [10’-1 1/8”] + 2x12 joists [11 1/4”] + 1 1/8” subfloor) ADA = yes Details= straight run; no platform; 52” wide framed. !!!PRACTICAL EXAMPLE # 3 !F2F = 10-1-12 = (9’ walls [9’-1 1/8”] + 11 7/8” TJI + 3/4” subfloor) ADA = no (The stairwell has 15’-10” run which the owner wants filled. Determine tread lengths.) Details= a platform will occur at step 5 and the stairs will turn 90 degrees. The ground floor will have 1/2” tile on 1/4” thinset on a slab. The landing will have carpet and the upstairs and each step will have 3/4” oak treads. The upstairs will have only a single oak tread at the top of the stairs that butts into carpet for the rest of the upper floor covering. !!!

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STAIR TOWER !!

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