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House has crawl space with a strange shape.

Home Construction Styles

Over the past several decades, construction preferences and styles have evolved and changed. In some styles, such as bungalows, minimal traditional and cape cod style homes from the 1920s to 1950s, the layouts stayed mostly within a rectangular frame. Once the ranch style home grew to prominence during the 1950s and 1960s, the footprints started getting more creative. With new attached garages, homes often have L- or U-shaped layouts. Newer designs in neo-colonial to modern style homes continue to have more unique angles and looks. Houses also vary in size from small modest homes to large mansions. With all the changes, very few homes have a perfectly rectangular crawl space footprint.

Examples of More Complex Crawl Space Layouts

We often see crawl spaces that are compartmentalized by additions or unique designs.

  • Layout for crawl space moisture control system
  • Layout for crawl space moisture control system
  • Layout for crawl space moisture control system
  • Layout for crawl space moisture control system

Ventilation in Crawl Spaces

In a traditionally vented house, passive vents are often installed all around the house perimeter. With odd-shaped crawl spaces, the air flow will often not easily pass over all areas of the space. These problems are greatly compounded when a house gets an addition or is segmented in the crawl space in some other way.

When we add mechanical ventilation with the use of fans, we generally suggest exhaust fans on one side of the house and intake fans on the opposite side to get a good cross flow of air. How many fans will vary based on size. However, there are times when the air from one side to the other will not pass over some corners or hard-to-reach areas.

Air flow of a crawl space with an ATMOX system installed

Balanced Air Flow

So, how do you solve this problem? It’s a very simple concept. We add joist-mounted fans to blow air into those hard-to-reach areas to aid the air movement of the exhaust and intake fans.

Even a rectangular house with an attached garage will have a “dead” corner or area.  As houses get more complex, the need for additional joist-mounted fans will increase.

Crawl Space Shapes and Sizes

It’s important to address all corners of the house and to be sure not to neglect any areas of the crawl space. You don’t want a mold or wood rot problem – even in just a small area. Take a birds-eye view of your crawl space to look at the shape and size to think about complete air movement when determining how moisture issues will be solved.

Post Author: ATMOX TOM