Rough-Framed Stairs - 03

Rough-Framed Stairs - 03


This week’s focus will be on TERMINOLOGY.

We all need to use common language to describe the components and parts that make up the stair system.  These terms are often regional across north America and I’m sure globally as well.

Stair Parts:

Building Codes | Stringer | Riser | Tread | Nosing | Fire Blocks

Thrust Plate | Spacing Ledger | Anchor Ledger | Pressure Blocks

So lets talk about these things.

Building Codes.  

The riser height and tread depth are strictly regulated and inspected. Specific allowable variations in the height of each riser or length of each tread, individually as well as collectively, is provided.  (IRC R311.7.4.1 Riser Height and R311.7.4.2 Tread Depth)

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. 


Study the (engineer and city/county approved) set of plans for your project.

Look for section views of the stairs; finished floor to floor heights; joist and sub-flooring types.


The diagonal structural component of the stairs that is typically cut from 2 x 12’s or LVL (Laminated Veneer Lumber)material.


The single unit of rise per step. 


The single unit of run per step.  

Nosing.  This is the length of tread that extends past the riser underneath it.  This can vary from 0 to 1 ¼” and can even be incorporated into sloped risers.  It’s purpose is to make transiting steps safer by presenting, what feels like, more tread depth to step on..

Fire Blocks.  

Solid draft stopping is typically required in the stud bays of all the walls that are part of the stairwell.  

Thrust Plate.  

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.

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.

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.

Pressure Blocks.  

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

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