Mr. Jason McJury and COSAA Anchor Committee Members   January 30, 2001
505 Huntmar Park Drive, Suite 210
Herndon, VA 20170

RE:   Comments regarding the proposed HUD/COSAA
Installation Committee testing protocol

Dear Mr. McJury:

After listening to the various comments from the conference calls and reading all of the material presented, we feel that we need to comment and document our concerns regarding the proposed HUD/COSAA Installation Committee testing protocol being discussed.

In all discussions, distinctions need to be made between "design" or "working load" conditions and "test" or "ultimate load" conditions.

Design loads, or the working loads, are established to provide a safe, secure structure. The primary Federal Standard regarding manufactured housing is the Manufactured Home Construction and Safety Standards, Part 3280. Others, including the Permanent Foundations Guide for Manufactured Housing, HUD-007487, also provide insight into the application of the design loads versus test loads.

Part 3280 gives basic design conditions, which must be met by all manufactured housing. Paragraph 3280.306 establishes the windstorm protection requirements. Briefly, all manufactured homes must have provisions for support/anchoring or foundation systems that will resist overturning and lateral movement of the manufactured homes as imposed by the respective design loads. The resistance to sliding and overturning is critical to the safety of the home. The wind loads, which can be sustained by a structure, are significantly higher when the home is at rest than once it begins to move. Therefore, foundation design assumes zero movement.

Paragraph 3280.306(f) requires that all anchoring equipment be capable of resisting an allowable working load equal to or exceeding 3,150 pounds, and capable of withstanding a fifty percent (50%) overload without failure, of the anchoring equipment. This paragraph does not allow movement at the working load. This is in keeping with standard engineering design practice, which assumes that at design conditions, foundations do not move. This stability is essential to provide safe structures.

John McDonald, former head of the Florida DMV described scenes from wind damaged homes as a "zipper" effect - having the appearance that the initial movement had allowed the overloading of the anchoring components, culminating in the destruction of the house. While Mr. McDonald's observations were far from a scientific study, we have observed similar conditions in our full scale field-testing. We have seen that once the at-rest condition is overcome, it takes as little as 2,500 pounds to keep a double-wide home moving.  With design lateral loads of as much as 30,000 pounds, allowing three inches (3") of movement by design would be disastrous.  This is why the design codes are so strict regarding sliding and overturning. Three inches (3") of movement, at design conditions cannot be tolerated.

Concerns & Comments
Jason McJury
January 30, 2001
Page #2

Further evidence that foundations are expected to remain in place without movement is provided in ASCE-7, Minimum Design Loads for Buildings and Other Structures, published by the American Society of Civil Engineers.  Paragraph 2.4.4 states: "Buildings and other structures shall be designed so that the overturning moment due to lateral forces (wind or flood) acting singly or in combination does not exceed two-thirds of the dead load stabilizing moment unless the building is anchored to resist the excess moment. The base shear due to lateral forces (wind or flood) shall not exceed two-thirds of the total resisting force due to friction and adhesion unless the building or structure is anchored to resist the excess sliding force." This same requirement is used for all standard building codes for conventional housing. Anchoring components, which are designed for these loads, and are tested for standard building code compliance, are allowed 1/8" movement at a test load equal to three (3) times the design load. This is indicative of how serious the engineering community is regarding "zero movement". Comparatively speaking, it is being suggested that the manufactured housing standards be established at 2400% less than conventional homes, when tested at design loads, and not test loads. This disparity is too great to ignore!

The importance of keeping the building at rest cannot be overstated - it must remain stationary. Allowing three inches (3") of movement at design conditions cannot be supported by any engineering rationale. The fact that something is difficult to achieve in some soils is not a valid reason for relaxing the design requirements for a home. If a national standard is to exist, it must be consistent with acceptable engineering practice and account for all design conditions, no matter how difficult the task may be.

Jason, please submit this letter to all of the members of the COSAA anchoring committee prior to our next scheduled conference call on February 5, 2001 at 2pm EST. We would be glad to answer and/or discuss our viewpoints with anyone and can be reached at (904) 384-8150.

Respectfully submitted,
PRODUCT TESTING, INC.