Pre-cast blocks are often referred to as "cinder" blocks and foundations utilizing this material are used on well over 80% of all modular construction installations. Typically building foundations utilizing pre-cast block have minimal site preparation. The blocks are placed upon a solid base pad resting directly on the ground. Usually there is no soil investigation to determine if the site can support the loads imposed. This type of foundation work is relegated for temporary smaller short-term lease modular buildings.
Poured-in-place grade beams are the next step in the foundation evolution. This is the industry's preferred foundation for permanent installation. This is due primarily to the reduced amount of formwork required. Poured-in-place installations may require a soils investigation to be performed to determine soil characteristics and values. These values are compared to the loads imposed by the structure and the beams are sized to distribute the loads evenly. Typically, the grade beam is finished at an elevation even or slightly above the surrounding soil. This allows the building modules to be pulled onto the prepared foundation then blocked with pre-cast blocks. The site is prepared by digging trenches at least 12" deep or below the frost line, where applicable, placing reinforcement steel and finally pouring minimum 3000 psi concrete.
Stem-wall building foundations more closely resemble conventional construction than the two listed above. This is the most costly type of foundation due to the extensive formwork and the fact that two different pours are required. A stem-wall is a perimeter concrete wall placed atop a larger footing. This type of foundation provides an enclosed crawlspace. Consideration must be given to access, ventilation and drainage of the crawlspace. Drainage must be addressed via sumps, French drain or other means. Stem-wall foundations are utilized only on permanent installations, often on uneven sites where the building is located on a slope.
From pad-on-grade to a full foundation system, Triumph has capabilities to develop any entity of foundation work for your modular construction project. Triumph has completed numerous building foundations including developing our own structural engineering.