What component should be installed before backfilling to help the foundation withstand soil pressure?

The floor frame should be installed before backfilling because it plays a critical role in distributing loads and providing stability to the foundation against the lateral pressure exerted by the surrounding soil. When backfilling, it is essential to have a solid framework in place, as this structure helps transfer and distribute the weight of the soil evenly across the foundation walls. This prevents potential movement or settling that could compromise the integrity of the foundation.

Other components, such as wall panels and roof trusses, are important for the overall structural integrity of the building, but they do not provide the necessary support against soil pressure during the backfilling process. A crawl space, while useful in certain foundation designs, does not offer the same load-bearing capacity as a floor frame, especially during the critical phase of backfilling. Therefore, the floor frame is the best choice for ensuring the foundation can effectively handle the pressures from the surrounding soil.