Reading Main Floor Plans

By Jason Hofer

1. Walls

The first thing people usually look at when looking at their home plans are the walls. We shade the walls on our plans to make them more defined, and easier to read.  There are a number of different types of walls:

  • Exterior Supporting Walls:  These are the main type of walls and will be constructed of 2×6’s, and generally spaced at 24” apart (or 24” on center), but in some cases in order to improve the wall strength, we’ll space them closer together.
  • Mechanical Walls or Plumbing Walls:  Sometimes we will also use a 2×6 wall inside the house in order to allow our trades room to run all the mechanical lines (heating, plumbing, and electrical) up to the next floor, or back down to the basement. These will usually be labeled as “Mechanical Walls” or “Plumbing Walls” on the plan.

Mechanical and Plumbing Wall Example

  • 2×4 Interior partition walls:  These are the walls that define and separate the interior spaces, but very rarely will they be used to support any significant weight.
  • Half Wall or 39” wall:   These walls will sometimes be used under your kitchen island to support the breakfast bar ledge, but are more commonly used to separate and define interior spaces without interrupting the sight lines, and disrupting that open feel of the room. We will also use them at the stairs in place of railing. Railings at stairs will be shown on the plan by using a half wall and drawing a thick dotted line down the middle of it to represent the spindles. If you look at your stairs you will likely see this shown at the stairs leading up to the second floor near the foyer, or sometimes along the living room/great room. Railings are typically 36” high; this is a building code requirement in Alberta.

Half wall and railing

2. Floor Joists

In most Shane Homes, the floor joists will run front to back. You’ll see the joist direction noted on the Main Floor Plan. We typically use joists that are 11 7/8” tall, but in some cases, such as when longer distances between beams or support walls, we’ll use 14” deep joists. Running the joists in that direction makes it easier for our Heating and Plumbing Contractors to run the lines to where they need them without having to go under, or through, the joists.

3.  Beams

Where joists need support, but are too far away from a supporting wall, that’s where we will use a beam. There are 3 different positions to place a beam in a floor system.
o A dropped beam is what is most common, and most economical. The floor joists will sit on top of the beam, and the beam will be positioned below the floor system.
• The other two are Flush or Semi-Flush. In these cases the joists will butt up against the beam and be connected to it with steel joist hangers.
o A Flush Beam will allow for a flat ceiling, but will also block access for mechanical (we cannot go through the beam). So, even though a flush beam will give you a nice flat ceiling, it will mean that we will have to route the heating and plumbing through another location. In these situations we are constructing boxes and bulkheads in order to ensure the mechanical can get to where it needs to go.
o A Semi-Flush beam is the in-between. The beam is still dropped, but is not completely below the floor joists. This can be used effectively in a breakfast nook to reduce the intrusion of a beam into the room, but still allow for mechanical to the room above without the need for bulkheads or box outs into the room.


Dropped Beam

A dropped beam separates the kitchen and nook in the Tofino II showhome in Hillcrest in Airdrie.

4.  Posts

Sometimes when viewing your plan you will see a box with an “X” drawn through it inside a shaded wall. Those are there to represent the location of a support post. These will reduce the span on beams that support the floor above so they will not need to be as deep, and thus won’t protrude down into the main floor as far. These posts will need to be supported from below by an adjustable steel column. We’ll go over the steel posts in more detail when we break down what is shown on our basement plans in another blog. Sometimes these posts will be labeled (ex: “3-2×6 Post”) if the specific post is required to be of a certain configuration to support the weight above it while still fitting into the available wall space.

In case you missed Part I, please click here.

Make sure to watch for Part III coming out next week which will provide more information on Reading Main Floor Plans including Lines, Notes and Details.