What Are Blocking, Foundation, and Tie-Down plans?

Get multiple no-obligation price quotes from suppliers in your area.

Just because the secure grounding of a mobile office takes less time, money and elbow grease than the laying of a foundation for a permanent structure doesn’t mean it’s as much of a “snap” as LEGO-brick building. All mobile offices and homes require detailed blocking, foundation and tie-down plans to ensure they’re properly secured to the ground for maximum occupant safety, particularly in high winds or on a terrain that’s uneven or prone to settlement.


According to Satellite Shelters Inc. of Chicago, a blocking plan details all of the information about the strategic placement of a building’s foundational supports, including concrete or hardwood blocks, lateral arms, and longitudinal stabilizing beams. The plan also outlines the loading of the unit onto the block-and-beam formation and the unit’s plumb leveling according to the evenness of the ground.


A foundation plan contains all the information from the full blocking plan plus details on the locations of the primary supporting piers, the pier pads, and any special piers supporting heavy fixtures inside the unit, as well as information on the ground’s load-bearing soil conditions. Foundation plans often include information such as load-bearing soil capacity, footer type (plastic, concrete, hardwood, etc.), foundation pad size, I-beam pier spacing, perimeter and centerline pier locations, and blocking of special piers for ancillary features, such as shear walls, bathtubs, bay windows and fireplaces.


A tie-down plan itemizes the numeration and placement of anchors, straps, ties, brackets, buffers, etc., for securing the mobile office to the ground to increase wind resistance and ensure stability in hurricane conditions. Tie-down plans could include information on torque probe readings for soil conditions that determine anchor type, number and spacing of anchors, straps and ties, etc. Make sure that your tie-down plan is specific to the type of surface on which your unit is going –grassy soil, gravel, tar-and-gravel, asphalt, concrete pavement, etc. — and that your dealer can supply the appropriate anchors, according to American Mobile Office of Warren, Mich.


Foundation and tie-down plans are usually incorporated into one plan, according to Satellite Shelters Inc.


Some municipalities may require certain types of plans to be in place beforehand. Lake Buena Vista, Florida, for example, requires blocking, foundation and tie-down plans in order to secure a permit for the building, according to the Manufactured Building Requirements Policy of the city’s Building and Safety Department. So be sure to check with your city or town’s building department to find out what kinds of plans are required for the grounding of your mobile office. Finally, check with your prospective mobile office dealer to make certain those plans will be included in the purchase, delivery and set up of each unit.