The wooden cages under mobile homes: a false foundation too often ignored

When buying a mobile home, attention is often focused on the condition of the siding, roof, or interior fittings. However, a critical element too often goes unnoticed: the type of foundation on which the home rests. In a significant number of cases, mobile homes rest on wooden frames, a widespread but fundamentally problematic practice.

In reading numerous pre-purchase inspection reports, I regularly find that these wooden cages are neither mentioned nor analyzed. This omission is concerning, as this type of support cannot be considered a permanent foundation that meets the requirements of the Building Code.

Why wooden cages do not constitute a suitable base

The Building Code requires that every building rest on a structural system capable of ensuring stability, durability, and load-bearing capacity. In practical terms, this means that the structural elements must be adequately:

– placed on a stable support;

– anchored to the ground to resist uplift and movement;

– fixed and attached to each other to ensure structural continuity;

– braced to resist lateral forces, especially wind.

The wooden cages used under many mobile homes generally do not meet any of these requirements. They are often simply placed on the ground or on unanchored blocks, without any real structural connection to the building. They do not form a continuous system, are not braced, and do not allow for adequate transfer of vertical and lateral loads.

In addition to this, there is another major factor: the durability of the material. The wood used for these cages is frequently exposed to soil moisture, freeze-thaw cycles, and biological degradation. Over time, this exposure leads to rot, gradual sagging, and a loss of load-bearing capacity.

A tolerated practice, but not compliant

It is important to make a clear distinction: the fact that a mobile home has been resting on wooden frames for several years does not make this situation compliant. This is a practice tolerated in some contexts, but it does not respect the fundamental principles of structural construction.

These wooden cages should be considered temporary or non-compliant supports, not a permanent foundation or base. A mobile home should instead rest on recognized supports, such as piles, stilts, properly installed concrete blocks, or a compliant foundation, depending on municipal requirements and soil conditions.

A major issue during a pre-purchase inspection

The absence of any mention or analysis of the wooden frames in an inspection report can give the buyer a false sense of security. However, the foundation of a building is one of the most important elements, as it determines the overall stability of the structure and future upgrade costs.

In a pre-purchase inspection context, this element should always be documented, explained and brought to the buyer's attention, so that they can make an informed decision and anticipate the required corrective measures.

In short, a seemingly well-maintained mobile home may nevertheless rest on an inadequate foundation. Ignoring the wooden frames means ignoring a real risk, both structural and financial.