Key Concept: Before leaving the factory, foldable or expandable modular units are typically tested for wind resistance in accordance with the European standard EN 1991-1-4. A common test result is a wind pressure resistance of 4.18 kN/m²-a figure that corresponds to a 50-year return period (i.e., a wind event expected to occur, on average, once every 50 years). In imperial units, this is approximately 87 psf (pounds per square foot). Regarding snow loads, similar products are typically tested to withstand 36–40.7 psf (depending on roof slope), and they are verified for seismic resistance at an intensity level of 8 (corresponding to a peak ground acceleration of 0.2g).
Implications for the Client: These figures represent the maximum performance limits achieved by the product under controlled testing conditions; they do not guarantee compliance with local building codes at any given site. Design requirements for wind and snow loads vary significantly across different regions in the United States-for instance, coastal hurricane-prone areas may require designs for wind speeds of 140–180 mph, while mountainous regions may see snow loads ranging from 30 to 70 psf. Clients must cross-reference the specific design load requirements of their intended site against the test data provided by the manufacturer. If the site's wind or snow load requirements exceed these test values, the structural safety limits of the unit are not sufficient; in such cases, additional engineering reinforcement or a change in site location will be necessary.
