26386 Federal Register / Vol. 63, No. 91 /Tuesday, May 12, 1998 /Rules and Regulations

1Note, i.e., the option of using the Table would

provide structural performance within permissible

deflection limits.

2One kind of roof design, which is specified in

footnote 7 of the Table, has been deemed to meet

the performance requirements of the Table without

the need for additional engineering analysis or load

tests.

DEPARTMENT OF HOUSING AND

URBAN DEVELOPMENT

24 CFR Part 3280

[Docket No. FR–4271–N–01]

RIN 2502–AH05

Manufactured Home Construction and

Safety Standards: Metal Roofing;

Interpretative Bulletin I–2–98

AGENCY: Office of the Assistant

Secretary for Housing—Federal Housing

Commissioner, HUD.

ACTION: Interpretative Bulletin.

SUMMARY: In January 1994 HUD

amended the Manufactured Home

Construction and Safety Standards to

improve the resistance of manufactured

homes to wind forces in areas prone to

hurricanes. In part, the amendments

provided that manufactured homes

designed to be sited in high wind areas

must be designed to resist either the

design wind loads in a specified

industry performance standard or

alternative wind pressures set out in a

prescriptive Table included in the

regulations. Some questions have arisen

concerning: Whether manufacturers that

design their products using the wind

pressures in the Table must provide roof

sheathing under metal roofing; and the

appropriateness of the testing of metal

roofing that has been done. Therefore,

the Department finds it necessary to

reiterate, through this Interpretative

Bulletin (IB), its current policy with

regard to the regulations. A related

advance notice of proposed rulemaking

is published elsewhere in today’s

Federal Register.

DATES: Effective Date: May 12, 1998.

FOR FURTHER INFORMATION CONTACT:

David R. Williamson, Director, Office of

Consumer and Regulatory Affairs,

Department of Housing and Urban

Development, 451 Seventh Street, SW,

Room 9156, Washington, DC 20410,

telephone: (202) 708–6401 (this is not a

toll-free number). For hearing-and

speech-impaired persons, this number

may be accessed via TTY (text

telephone) by calling the Federal

Information Relay Service at 1–800–

877–8339.

SUPPLEMENTARY INFORMATION: In this

Interpretative Bulletin (‘‘IB’’) HUD

clarifies the meaning of the standard in

24 CFR 3280.305(c)(1)(ii)(B) as applied

to metal roofing. Under this provision,

elements of manufactured homes that

are designed for high wind areas

currently must be designed to resist

wind pressures prescribed in a Table of

Design Wind Pressures (‘‘Table’’).

(Alternatively, under

§ 3280.305(c)(1)(ii)(A), the design may

be qualified using general performance

standards that utilize the design wind

loads in ANSI/ASCE 7–88; this IB does

not affect the option to use those

performance standards.) This IB is

issued pursuant to 24 CFR 3280.9 and

3282.113.

HUD has received requests from

manufacturers and Design Approval

Primary Inspection Agencies (DAPIAs)

for clarification of design and testing

requirements for metal roofing in wind

zones II and III under the provisions in

§ 3280.305(c)(1)(ii)(B). Because these

requirements are not being applied

uniformly by DAPIAs and

manufacturers, and HUD agrees with

industry representatives that the

regulation needs clarification, the

Secretary has determined that the

public’s interest in the manufacture of

housing that is safe for the conditions

under which the housing is sited would

best be served by the issuance of this IB.

Issuance of the IB also is in the interest

of competitive fairness to members of

the industry. This IB does not denote

any change in policy or interpretation

formulated by HUD, but clarifies

requirements that were adopted as part

of an extensive notice-and-comment

rulemaking process.

Therefore, because of the need for

resolution of any question regarding the

requirements applicable under the

Manufactured Home Construction and

Safety Standards (‘‘standards’’) to metal

roofing in wind zones II and III, and the

fact that this is not a change in the

position or policy of the Department, in

accordance with 24 CFR 3282.113, the

Secretary has deemed it not to be in the

public interest to issue the

interpretation for public comment under

24 CFR part 3282, subpart C.

The Department understands,

however, that there may be concerns

about the requirements or

implementation of roofing standards for

manufactured homes sited in high-wind

areas. In that regard, persons interested

in recommending any changes to the

policy clarified in this IB are directed to

the advance notice of proposed

rulemaking published elsewhere in

today’s Federal Register.

Background

The manufactured housing

construction standards in 24 CFR

3280.305(c)(1)(ii) for wind zones II and

III were established by HUD in a rule

published on January 14, 1994 (59 FR

2469) (‘‘January 1994 rule’’). It is clear

from the history of this rule, which

amended the Federal Manufactured

Home Construction and Safety

Standards in 24 CFR part 3280 to

improve the resistance of manufactured

homes to wind forces in areas prone to

hurricanes, that HUD was intending to

create prescriptive standards that

manufacturers could elect to comply

with as an alternative to the general

performance standards that utilize the

design wind loads in ANSI/ASCE 7–88.

In particular, the January 1994 rule

provided that each manufactured home

designed for wind zones II or III must

be designed to resist either the design

wind loads in ANSI/ASCE 7–88 or the

wind pressures specified in the Table.

A question has been raised

concerning whether manufacturers that

design their homes using the wind

pressures in the Table must provide roof

sheathing under metal roofing to meet

the requirement for resisting the wind

pressures specified for roof coverings in

the Table. Although the preamble of the

January 1994 rule does not address the

issue of metal roofing and roof

sheathing directly, there is ample

evidence of HUD’s objectives in

establishing the higher wind standards.

The January 1994 rule clearly reflects

HUD’s intent to provide, through the

prescriptive Table, an option that would

provide comparable rigidity (‘‘a rigid

box’’),1 as an alternative to designing

manufactured homes using the design

wind loads of ANSI/ASCE 7–88. This

intent also is consistent with the

statement in § 3280.301 that subpart D

of 24 CFR part 3280, which includes

§ 3280.305, is intended ‘‘to assure that

the manufactured home will provide: (a)

Structural strength and rigidity * * *.’’

The January 1994 Rule

Although it is more prescriptive than

the ANSI/ASCE 7–88 performance

standard, the Table allows

manufacturers to use alternative

materials for the roof structure as long

as those materials, and the entire

manufactured home, meet the

requirements in the Table.2 In

explaining the need for the January 1994

rule, HUD noted that storm damage to

manufactured housing is primarily in

the form of roof failure, loss of roof

diaphragm material, connection failures,

and tiedown/foundation failures. HUD

also noted that in Hurricane Andrew,

manufactured homes ‘‘became

dangerous flying missiles, inflicting

more property damage on neighboring
Federal Register / Vol. 63, No. 91 /Tuesday, May 12, 1998 /Rules and Regulations 26387

3See attachments to the comments submitted by

the Manufactured Housing Institute (commenter

#112 in Docket #FR–3380) on the proposed rule that

was finalized in the January 1994 rule.

structures.’’ (See 59 FR at 2457,

‘‘Problem to be Addressed.’’) In the

‘‘Summary’’ in the preamble of the

January 1994 rule, HUD stated: ‘‘The

revised standard also requires exterior

roof and wall coverings to be fastened

adequately to sheathing and framing

members, to resist higher design wind

pressures. The purpose of this rule is to

increase the safety of manufactured

homes, thereby reducing deaths and

injuries and extensive property damage

losses in areas where wind-induced

damage is a particular hazard and risk.’’

(59 FR at 2456.)

Also in the preamble, HUD related

that ‘‘[a]mong the major deficiencies

contributing to manufactured housing

damage in Hurricane Andrew were

inadequate connections between

exterior roof or wall coverings and

supporting sheathing or framing and

between walls, roofs, and floors’’ (59 FR

at 2458, ‘‘Field Investigations’’). This

portion of the preamble continues:

In particular, losses of roof coverings were

widespread, and were considered by some to

be the first mode of failure for manufactured

homes damaged in Hurricane Andrew. Other

roof-related damage was due to loss of

sheathing, failure of connections, or a

combination of these problems * * *

* * * Metal or plastic siding used in

manufactured housing was readily damaged

or penetrated by flying debris during the high

winds in Hurricane Andrew. Loss of roof or

wall cladding allows the building to be

penetrated by the weather and has farreaching consequences beyond the area of

envelope integrity.

* * * In addition, failure of coverings

or attachments to the manufactured

home structure also caused missile-type

damage to other homes.

* * * Edges and corners of roofs and

endwalls of manufactured homes

appeared to have been particularly

vulnerable to the high wind forces,

according to the damage typically

reported in these areas * * * (59 FR at

2458)

Later in the preamble, these same

themes were sounded. For example:

‘‘Commonly observed failures included

loss of roof membranes and blow-off of

roof sheathing * * *.’’ (59 FR at 2458.)

HUD also cited a Federal Emergency

Management Agency (FEMA) report on

the damage in Hurricane Andrew:

It was observed that the breakup of

corrugated metal siding and roofed buildings

such as manufactured homes and preengineered metal frame buildings contributed

significantly to the generation of airborne

debris. This was evident from debris damage

to nearby downwind structures.

(59 FR at 2462, ‘‘Cost Considerations’’).

HUD did state its expectation that the

manufactured housing industry would

be innovative in developing designs,

components, and construction

techniques that meet the standards but

maintain the affordability of

manufactured homes. It was clear,

however, that the final product would

be expected to perform at an acceptable

level. In fact, HUD’s stated intent was to

strengthen the requirements for

structural assemblies, components,

connectors, fasteners, and a number of

other areas so that the manufactured

home would be able to resist the same

wind forces as required for site-built

and modular housing. (59 FR at 2467.)

HUD also notes that the economic

analysis prepared by an industry trade

association factored into the predicted

costs of compliance with HUD’s higher

wind standard proposals the cost of roof

sheathing.3 Therefore, the indications

are that the industry itself, at the time

the rule was being developed,

understood that the requirement was for

a rigid box.

Finally, in summarizing the changes

made by the January 1994 rule to

§ 3280.305(c), the preamble states that:

Exterior roof and wall coverings (excluding

glazing), sheathing, and fastenings need not

be evaluated for the design pressures

specified by the Table, when fastened to a 3/

8′′ structural rated sheathing and the

sheathing is oriented and secured to framing

members in accordance with the fastening

schedule specified in the Table. (59 FR at

2467.)

An IB that was published by HUD in

the Federal Register on July 1, 1994 (59

FR 34294), further bolsters the intent of

the January 1994 rule. In that IB, HUD

recognized that metal siding (such as

vertical steel siding) could, under strict

circumstances, be approved as both a

structural wall sheathing and an exterior

covering material. The strict

circumstances specified in the IB

ensured that the metal siding/exterior

covering would, in effect, maintain a

rigid box, including covering and

fastening requirements, and would

resist the full design pressures specified

in the Table. The same reasoning

applies to metal roofs in Wind Zones II

and III in this IB.

Subsequent Testing of Metal Roofs

In reviewing tests performed under

the higher wind standards on metal roof

systems without sheathing, the

Department has found that none of the

tests satisfied all of the requirements of

the standards. The test methods used

introduced additional resistance for the

test assemblies that would not be

available under actual conditions of

application or construction, contrary to

the requirements of § 3280.303(c). The

test methods also did not consider the

combined effect on fasteners and

components of horizontal wind forces,

nor the compression load added as a

result of the sole use of metal roofing

without sheathing. The tests also did

not measure deflection, as required

under § 3280.401 and as would be

necessary to ensure compliance with

§§ 3280.305 (a) and (h).

Other specific questions about the

tests include:

• Concerns about whether the

laboratory tests simulated factory

conditions for replicating the

workmanship associated with the small

edge distance and installation of the

large number of fasteners required;

• The ability of the quality control

system to prevent production problems

that would be caused because of the

large number of fasteners required and

the small edge distance for the

outermost row of fasteners at the metalto-rim rail connection of the roof, which

is likely to cause damage to wood rim

members or tearing of the metal during

production or when design wind loads

are applied;

• Failure of the tests to include all of

the fasteners required in actual

production, which would have further

damaged the rim rail and weakened the

tested assemblies; and

• Lack of information about

deformation criteria for the connectors

(fastener slip) or other conditions that

would constitute failure of the test

assembly, such as rim rail rotation.

Accordingly, under the authority of

42 U.S.C. 3535(d), Interpretative

Bulletin I–2–98 is issued by the

Department as follows:

Note: HUD Interpretative Bulletin I–2–98

will not appear in the Code of Federal

Regulations.

Interpretative Bulletin I–2–98—

Manufactured Home Construction and

Safety Standards: Metal Roofing (24

CFR Part 3280)

Under section 604 of the National

Manufactured Housing Construction

and Safety Standards Act of 1974, 42

U.S.C. 5403, the Secretary is authorized

to establish, amend, and revoke by order

appropriate Federal manufactured home

construction and safety standards

(‘‘standards’’). On January 14, 1994 (59

FR 2456), HUD published certain

changes to the standards for high wind

areas, as codified in 24 CFR part 3280.

Subsequently, HUD has published

interpretations of the January 1994 rule

at 59 FR 19072 (April 21, 1994) and 59

FR 34294 (July 1, 1994). In the April 21,
26388 Federal Register / Vol. 63, No. 91 /Tuesday, May 12, 1998 /Rules and Regulations

1This designation indicates that this is the second

interpretive bulletin issued in 1998. The

interpretive bulletin issued on February 18, 1998

(63 FR 8330) was not officially designated as I–1–

98 because it was an amendment to an earlier

interpretative bulletin designated as J–1–76.

2 In order for the metal roof to resist the uplift

loads applicable in Wind Zones II and III and

transfer the design loads, the Department expects

that the metal roof would be fastened to the support

members (trusses, edge members, etc.).

3This concern with deflection measurements, and

the concept of a sound structural frame, are also

seen in § 3280.305(h), which specifically requires

that roofs be of sufficient strength to withstand the

load requirements in § 3280.305(c) without

exceeding established deflections, and in

§ 3280.305(a), which states:

Each manufactured home shall be designed and

constructed as a completely integrated structure

capable of sustaining the design load requirements

of this standard, and shall be capable of

transmitting these loads to stabilizing devices

without exceeding the allowable stresses or

deflections* * * .

1994, Interpretative Bulletin, HUD

indicated that it may issue additional

Interpretative Bulletins to provide

further assistance in the implementation

of the new standards. This Interpretative

Bulletin I–2–98 1 is issued to clarify

requirements applicable to the use of

metal roofing in wind zones II and III.

All section references are to sections of

24 CFR part 3280.

HUD interprets § 3280.305(c)(1)(ii)(B)

to require every design for

manufactured housing for high wind

areas to include roof sheathing or

alternative roof material that performs

like sheathing in resisting the wind

pressures specified in the Table of

Design Wind Pressures (‘‘Table’’),

whenever the Table is used as the basis

for qualifying the design. The phrase

‘‘performs like sheathing’’ means that

the roofing system will transfer the

higher wind loads to which the Table is

formulated to structural support

members and components without

compromising the integrity of those

members and components to such an

extent that they cannot resist the

applicable design pressures specified in

the Table.2 In developing the Table,

HUD contemplated a design that utilizes

structural rated roof sheathing that is at

least 3⁄8 of an inch thick and is installed

in accordance with footnote 7. If roof

sheathing is not used in the design for

the roof system, in accordance with

§ 3280.303(c) load tests or engineering

analyses used to determine that the

manufactured home complies with the

Table must account for the additional

high-wind loads transferred to other

parts of the structure because of the

absence of separate load-resistant

sheathing. Thus, metal roofs without

sheathing may be used if they are strong

enough to perform like sheathing and

can meet all of the requirements

discussed in this paragraph.

When separate sheathing is utilized in

a design, the sheathing must be shown

to be capable of resisting the wind

pressures specified for sheathing in the

Table, unless the sheathing is structural

rated roof sheathing that is at least 3/8

of an inch in thickness and is installed

and secured as provided in footnote 7 of

the Table. A manufacturer that includes

in its design sheathing that complies

with the specifications set out in

footnote 7 can avoid having to

substantiate the sheathing as being in

compliance with the loading

requirements for sheathing in the Table.

In both of these cases, however, all other

loading requirements in the Table and

requirements of the standards would

still have to be met.

Of course, manufacturers continue to

have the additional option, set forth in

§ 3280.305(c)(1)(ii)(A), to design any

manufactured home, including the roof

(metal or nonmetal), using the design

wind loads for Exposure C as specified

in ANSI/ASCE 7–88 and the applicable

design wind speed.

Testing Protocols

To be acceptable under the standards,

all roofs, including metal roofs, must be

designed using either engineering

analysis or suitable load testing

protocols, in accordance with

§ 3280.303(c). Until the higher standards

were adopted for wind zones II and III,

metal roofs for manufactured homes

generally had been qualified using

engineering analysis. Manufacturers

have chosen to test metal roofs intended

for wind zones II and III using the

design wind pressures in the Table,

apparently because the metal roofs may

not have been able to qualify under the

higher standards through engineering

analysis.

The regulations set forth a series of

requirements regarding testing. Under

§ 3280.303(c), if the strength and rigidity

of a unit or component is to be

determined by testing, the load tests

must replicate the actual loads and

conditions of application, not just

approximate those loads and conditions.

A manufacturer relying on § 3280.401 to

establish the acceptability of a

compliance alternative also must meet

all of the requirements established in

that section. Section 3280.401(b), for

example, requires that deflection

measurements be taken.3 Further, if a

manufacturer cannot perform an

engineering analysis to demonstrate

compliance with the § 3280.305(h)

design requirements for roofs and the

§ 3280.305(c) design requirements for

systems, components, and framing, the

manufacturer must comply fully with

established testing protocols or obtain

HUD approval of special testing under

§ 3280.303(g).

Section 3280.303(g) allows for the

development of special testing

procedures that demonstrate structural

properties and significant characteristics

when there is no recognized or suitable

testing procedure. In the absence of an

established suitable testing protocol, a

manufacturer that wants to establish

compliance with a standard through

testing must submit the testing protocol

to HUD for approval. HUD would

anticipate that such a protocol would

address test set-up, loading apparatus,

and size and dimensions of the test

assembly, and would establish failure

criteria. Section 3280.303(g) places the

burden on manufacturers for developing

such testing procedures to demonstrate

structural properties and significant

characteristics of a material, assembly,

component, or member.

Summary of Requirements, Using Table

Because there has been confusion

about the requirements of the

regulations in question, HUD will allow

a grace period of 30 days after the date

of publication of this IB for compliance

with the requirements as clarified in

this IB. Thus, in qualifying any roof

through testing, HUD will not recognize

as being in compliance with the

requirements of the Table a metal roof

system that is installed on any unit for

which the manufacturing process is

completed beyond the grace period,

unless that metal roof system is able to

resist the appropriate wind pressures

specified in the Table and complies

with at least one of the following

conditions:

(1) The metal roofing is a covering,

which is designed to resist the

applicable wind pressures specified for

roof coverings in Table and is installed

in conjunction with structural rated roof

sheathing that is at least 3⁄8 of an inch

in thickness and is fastened as provided

in footnote 7 of the Table;

(2) The metal roofing is a covering,

which is designed to resist the

applicable wind pressures specified for

roof coverings in Table and is installed

in conjunction with roof sheathing that

does not qualify as acceptable

automatically under footnote 7 in the

Table, but that has been qualified

through engineering analysis or

appropriate testing procedures as

capable of resisting the wind pressures

established for roof sheathing in the

Table; or

(3) The metal roof itself has been

tested, using procedures that either meet

all of the requirements of §§ 3280.303(c)
Federal Register / Vol. 63, No. 91 /Tuesday, May 12, 1998 /Rules and Regulations 26389

4See footnote 2, above.

and 3280.401 (or another suitable load

test) or have been developed and

approved in accordance with

§ 3280.303(g), and the metal roof has

been determined to perform like

sheathing by transferring the higher

wind loads to structural support

members and components without

compromising the integrity of those

members and components to such an

extent that they cannot resist the

applicable design pressures specified in

the Table.4

As noted, in the absence of recognized

testing procedures, a manufacturer may

develop and submit to HUD for

approval, in accordance with

§ 3280.303(g), a testing procedure that

would demonstrate the requisite

structural properties and significant

characteristics of the alternate design or

material.

Authority: 42 U.S.C. 3535(d) and 5424.

Dated: April 29, 1998.

Art Agnos,

Acting General Deputy Assistant Secretary

for Housing.

[FR Doc. 98–12341 Filed 5–11–98; 8:45 am]

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