In addition to the standard pier supports currently used to support vertical loads, there are other devices used for supplementary bracing that are not required by Department regulations.
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Tiedowns:
Tiedown systems have been required by manufactured home manufacturer's installation instructions since 1971 to meet the manufactured home's design capacity; however, tiedowns are only required by Department regulations for singlewide manufactured homes installed in areas with documented wind loads in excess of 15 pounds per square foot. Testimony provided at Department Fact Finding Hearings indicated the average cost of installing tiedowns on a 24' X 60' doublewide manufactured home was $1,000. (5 per chassis beam X 4 chassis beams = 20 X $50)
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Saddles and Locking Top Devices:
As indicated earlier the standard steel and concrete pier supports have an adjusting bolt and a flat piece of steel at the top for the manufactured home chassis to rest upon. The "saddle" and "locking" top devices replace the flat piece on top of the adjusting bolt and more securely connect the pier to the manufactured home. Testimony provided at Department Fact Finding Hearings indicated the average cost of installing locking devices on steel piers supporting a 24' X 60' doublewide manufactured home was $528. (44 piers X $12)
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Marriage Locks:
A "marriage lock" is a device designed to connect the chassis of multiwide manufactured homes together. The purpose of these devices is to improve the structural integrity between the separately transportable sections of multiwide manufactured homes. Generally these devices consist of a threaded steel rod running through or below the chassis at a 90 degree angle. They are mechanically connected to the chassis with clamps and locking nuts. Three-to-four marriage locks are normally installed between the separate transportable sections of multiwide manufactured homes. Marriage locks are an after market item primarily sold and installed in conjunction with Earthquake Resistant Bracing Systems. Testimony provided at the Department's Fact Finding Hearings indicated that the cost of installing marriage locks on a 24' X 60' manufactured home would be $360. (3 X $1 20)
Heavy Duty Piers, Super Piers and Safety Jacks:
These types of devices are typically steel piers designed and manufactured to carry as much as 10 times the load of a standard steel pier. The base of these piers is generally 1.5 to 2 times wider than the standard pier and they are equipped with a locking mechanism at the top to secure the pier to the chassis of the manufactured home. These devices are marketed as a replacement pier with claims of improved stability and strength. Normally, these type of piers are installed as replacements to every third or fourth standard steel pier under an existing manufactured home. Testimony provided at the Departments Fact Finding Hearings indicated that the cost of installing these piers under a manufactured home would be $1,800. (12 X $150)
Earthquake Resistant Bracing Systems (ERBS):
Department regulations require all ERBS, prior to being sold or installed under manufactured homes in California, to be certified by the Department. As a condition of certification, Department regulations require that manufacturers of ERBS obtain a listing from a Department approved listing and/or testing agency. The listing provides assurance that ERBS complies with Department regulations for the design and construction of ERBS.
The design criteria for ERBS contains two basic elements. First, the ERBS must be designed and constructed to resist seismic forces while supporting the manufactured home; and, second, the ERBS must be designed and installed to limit any downward vertical drop of a manufactured home displaced from its primary support system to a maximum of 2 inches.
The installation of an ERBS is an option of the manufactured home owner. During the Loma Prieta Earthquake less than 4 percent of the manufactured homes surveyed by the Department had ERBS installed. The Department's preliminary report entitled "Evaluation of Manufactured Housing Support System Performance in the Loma Prieta Earthquake" (Attachment A) reported no failures of ERBS that had been installed. Testimony provided at the Department's Fact Finding Hearings indicated that the average cost to have an ERBS installed under a typical 24' X 60' manufactured home was $2,500 while the average cost of damage to manufactured homes, accessory structures and utilities in the Loma Prieta Earthquake was from $12,000 to $15,000.
While ERBS have demonstrated their ability to perform as designed, they continue to allow for the home to fall as much as 2". The home still has to be reset on its support system and accessory structures are still damaged.
