A crucial trade in the home-building world is the walls and fencing! And this can be a tricky one if you’re not careful. Now unlike the other land development trades, the walls and fencing don’t necessarily start in any specific order. Perimeter walls can be installed as soon as the rough grading is finished while the side P/L walls can go in later when the houses are being built.

Although the walls may seem like a fairly simple concept to wrap your head around, there are a few details that you MUST know when dealing with this trade. If you don’t, it could hurt you in the end!

In this post we will be discussing:

1. General Sectional Wall Terms
2. CMU Block Wall Types
3. Wall Height Calculations
4. Retaining Walls
5. Other Fencing (Vinyl and Tube Steel)

GENERAL SECTIONAL WALL TERMS

1. Perimeter Walls (below in red) – all the walls surrounding your site that separate your tract from all other areas around it (including any perimeter streets).
2. Side P/L Walls (or “Property Line” walls) (below in green) – these are all the side walls separating each individual homeowner’s property line from one another.
3. Spine Walls (below in purple) – This is similar to the P/L walls. However, this is the rear P/L that separates the houses that are back to back from each other.
4. Return Walls (below in blue) – These are the walls in between the houses that face the street (usually where the side access gates are located). These walls “return” off of the side P/L walls.

CMU BLOCK WALL TYPES

CMU stands for “Concrete Masonry Unit”. It is the most common type of walls in land development construction and can come in a few different styles. They are:

1. Precision Block (8″ high)
2. Split Face (8″ high)
3. Slump Stone (6″ high)

To see more block styles and examples, you can visit Orco’s website here.

WALL HEIGHT CALCULATIONS

One of the biggest things to keep in mind when contracting or budgeting for your walls is the height! The height of a SINGLE standard CMU block is 8” (for a precision block or a split-face block as stated above), therefore, each course (or level) of the wall is also 8” high. Also keep in mind, typically when you build a masonry wall the bottom 4”-6″ of the first course is usually going to be buried.

So for example, if the “Conditions of Approval” for your tract is requiring a 6’-0” high wall MINIMUM, then you will need at least 10 courses in your wall with a 2” cap on top (or 9 courses if your cap is 4″ high!). (See calculation example below for SPLIT-FACE or PRECISION block.)

Notice how in the example shown above the wall height is more than 6′. However, if you take one course away (which is 8″), you will now be less than the required minimum height of 6′.

(See below for calculation example for SLUMP STONE. Remember, the height of a slump stone block is 6″. That’s 2″ LESS than a split-face or precision block as mentioned above. Which means we’ll need more courses.)

RETAINING WALLS

These types of walls “retain” earth. They may be required for different reasons. One of the main reasons could be because the rear or side yards of a house may not meet the minimum setback requirement from the back of the house to the toe of slope (as dictated by your local jurisdiction). Therefore, a retaining wall would be used to retain the slope and give more “livable” space to the homeowners. (See example below).

OTHER TYPES OF FENCING

Other types of walls and fencing that are also used within communities are vinyl and tube steel.

VINYL

This type of fence is also very common. It’s cheaper than masonry walls and still looks nice. BUT, you have to make sure you do your research and due diligence because some jurisdictions may not allow it! For instance, some jurisdictions may limit vinyl to just side P/L and spine walls and allow masonry for the return and perimeter walls. (That way all walls that can be seen from the street will be masonry and not vinyl). ON THE OTHER HAND! Other cities won’t allow ANY vinyl at all! And some cities may not even have a preference.

But again, it’s important you do your due diligence! Because if you budget for vinyl and you find out later that the city requires all block walls, you could be looking at a cost difference of about $50 / LF! Depending on how big your job is, that can add up to hundreds of thousands of dollars!

TUBE STEEL

This fence is a great option for projects that offer great views, but still need to restrict public access. This could be for basins, or for private rear yards with a spectacular view, etc.

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