Tie-downs are essential to the structural safety of manufactured homes as they prevent homes from any uplift and turning from strong winds. Tie-downs and anchors are responsible for stabilizing your home to the ground. The number of tie-downs and the kinds of anchors to be used will depend on your climatic region (wind zone, coastal area) and soil type.
Tie-downs are heavy-duty galvanized steel straps and anchors designed to keep your manufactured home stable and fastened to the ground in extreme weather and strong winds. Without these straps or if improperly installed, puts your home at risk of sliding and overturning. Tie-downs properly installed and well maintained will last long term. (1,2)
Since manufactured homes are built economically, many of these are more lightweight compared to site built homes. Also being elevated, these homes become more prone to strong winds if not secured and stabilized correctly. Part of the HUD Code (U.S. Department of Housing and Urban Development) made in 1976 states that all manufactured homes must have approved tie down straps “which help stabilize the structure against movement caused by environmental forces.” (1)
This building standard and requirement was further reinforced in the early 1990’s.Therefore, if buying or living in an older mobile home, be absolutely sure and have your tie-downs inspected by a professional engineer or contractor. Have them update your tie-downs and anchors to modern safety standards.
In hurricanes, tornados and windstorms, manufactured homes won’t be a safe space until you anchor your home as per code with tie downs.
This is due to their lightweight nature and ability to still be a “mobile home” with wheels, manufactured homes aren’t required to have permanent foundations. Instead, a more common foundation system for these homes are being elevated on concrete piers. This provides great energy efficiency and ventilation for the home, but in times of storms the high winds can flow underneath and possibly create an uplift, roll or flip. Given their build and structure, this is why it is crucial to ensure your tie downs are up to date. (2,3)
There are two main types of tie downs needed to stabilize your home:
Vertical Tie Down: This is used above the roof of the home to prevent wind damage. Depending on the home’s length, 2-4 tie downs can be used per side. More can be installed for greater safety against storm damage.
Diagonal Tie Down: This ties the home’s structural frame down to the ground and prevents winds from lifting or creating an “uplift” of the home.A home would need 3-5 per side if located in areas less prone to storms. If located in a storm prone or coastal area, 4-7 tie downs are recommended per side.
Single wide homes will need both kinds of tie-downs. Double wide manufactured homes may only require diagonal tie downs to anchor the home’s frame down. (3)
There are numerous kinds of tie downs and installation methods, however the most popular ones you’ll come across are “over the top” and “frame anchors.”
“Over the top” tie downs consist of a concealed flexible metal strap that wraps around the roof and underside of the structure and is secured using ground anchors to fasten the structure to the adjacent grade and/or slab. “Frame anchors” are metal straps or bars that attach to the chassis or “frame” of the home and anchor to a concrete footing and/or slab beneath the structure. From Tie-Downs for Manufactured Homes – InterNACHI® (1)
The amount of tie downs you need will depend on the length and size of your home as well as your location. If located by the coast or high wind zone areas, more tie downs will be required as more storms are expected. Always have an engineer check the exact structural requirements for your home.
Diagonal tie downs are essential for both single wide and double wide homes as they secure the home’s steel chassis or structural frame by its frame anchors. Anchors are chosen based on the home’s location and soil type. There are anchors better suited for hard clay soils and other anchors for more sandy soils. If a permanent foundation of poured concrete is used, concrete anchors will be utilized.
Be sure to consult a building inspector or professional installer for tie-down installation as they will make sure all materials and processes are building code compliant. First, ensure your home is level before anchoring. Then they will consider any hazards that may be present in your site location and add ties as needed. The anchoring supplies must meet code standards being corrosion and weather resistant. (4)
While consulting your professional installer, also inquire on the different kinds of tie downs and anchors your home might need and why. Find out what anchor you need specifically for your soil. (2)
To maintain your tie-downs and make sure they are in tip top shape, here are a few safety and maintenance tips from InterNACHI inspectors: (1)
- Check for loose straps, they must all be tight and straight.
- Replace any straps or anchors showing signs of corrosion or damage
- Replace any straps that are kinked, bent or unusually stressed
- Protect straps at sharp edges with radius clips
- Anchors must be installed to their full depth/length.
- Ask your local building department for the minimum number of straps required for your area and check if your home is compliant.
In short, tie-downs are essential in greatly stabilize your manufactured home from severe wind damage. For more on maintaining tie-downs and the different types of tie-downs, check out Tie-Downs for Manufactured Homes – InterNACHI®
References:
- Gromicko, N., & Shepard, K. (n.d.). Tie-downs for manufactured homes. InterNACHI®. Retrieved July 2022, from https://www.nachi.org/manufactured-home-tie-downs.htm
- American Modern. (2020, June 8). Tie-downs are crucial for manufactured homes. American Modern Insurance – Agents. Retrieved July 2022, from https://www.amig.com/agents/blog/your-manufactured-home-and-tie-downs/
- Campbell, J. (n.d.). Tie-down requirements for manufactured homes. eHow. Retrieved July 2022, from https://www.ehow.com/about_5209049_tie_down-requirements-manufactured-homes.html
- Hazelwood, J. (2022, February 10). Tie downs for manufactured homes. Nonprofit Home Inspections. Retrieved July 2022, from https://nonprofithomeinspections.org/tie-downs-for-manufactured-homes/
