Z240 MH Series Manufactured Homes

Z240 MH Series Manufactured homes

Proposed Updates to 2009 Edition

Technical Committee Review of Draft – 06 January 2014

Z240.2.1 Structural Technical Requirements for Manufactured Homes

A. General Approach

Z240.2.1 currently addresses much more than structural design; it is proposed that this part of the MH Series re-titled Technical requirements for manufactured homes and serve as the main technical standard for this product.

The National Building Code is referenced in the general requirement and provisions have been retained only as needed to provide additional requirements or exceptions that are particular to manufactured homes. This allows the withdrawal of Z240.9.1 on load calculations an ducting. A cross-reference to Z240.4.1 has been added. (Z240.4.1 and Z240.5.1 are proposed to be combined to reduce repetition; see Z240.4.1 and Z240.5.1 below.) The document “Z240.2.1 Contents” indicates where provisions have been added or deleted.

B. Technical Changes, and Unique Editorial/Technical and Editorial Changes

/ Provision / Edit’l or Tech’l / Summary of Change(s) / Reason / Support For Change / Reason
Must be provided where support is qualified or change is not supported / Suggested solution /
Yes / Yes with comment or revision / No /
Title / E/T / Change “Structural” to “Technical” / The requirements currently provided in Z240.2.1. go far beyond what are normally considered to be structural requirements.
1 / Scope
1.1 / preamble / E / Replace “quality of work” with “practice” / “Quality” is undefined and open to interpretation. “Practice” more accurately describes what the standard addresses.
Clause (a) / E / Add “including resistance to vibration and deflection” / To provide information on what is included in “rigidity”
Clause (d) / E / Delete Clause / Redundant; addressed by Clause (b) and by other objectives
Clause (e) / E / Delete Clause / “Durability” is an undefined term. Redundant; addressed by Clause(b)
Clauses (d) to (g) / E / Insert objectives / To recognize issues addressed in the Standard; consistent with NBC objectives
2 / Reference Publications
preamble / T / Refer to editions in force at the installation location / Keeps the standard up to date with the codes or standards referenced by the AHJ where the MH Series is recognized
CSA
CAN/CSA-A440 & A440.1 / T / Delete / The CSA A440 standard and A440.1 User guide have been superseded by the referenced AAMA/WDMA/CSA standard (see below)
CAN/CSA-B365 / E / Delete / Redundant; referenced through reference to NBC
CAN/CSA-B366.2 / E / Delete / Redundant; referenced through reference to NBC
CAN/CSA-O86 / __ / No change / Retained; referenced in a note.
CAN/CSA-O132.2 / E / Delete / Redundant; referenced through reference to NBC
O132.5 / E / Delete / Redundant; referenced through reference to NBC
O141 / E / Delete / Redundant; referenced through reference to NBC
CAN/CSA-S16.01 / E / Delete / Redundant; referenced through reference to NBC
CAN/CSA-S136 / E / Delete / Redundant; referenced through reference to NBC
CAN/CSA-S136S1 / E / Delete / Redundant; referenced through reference to NBC
CAN/CSA-S157 & S157.1 / E / Delete / Redundant; referenced through reference to NBC
S307 / E / Delete / Redundant; referenced through reference to NBC. Note: Reference to this standard may be deleted from the NBC as compliance is normally by calculation..
CAN/CSA-Z240.4.1 / E / Insert / Proposed to be referenced in Z240.2.1
AAMA/WDMS/CSA / E / Delete / Redundant; referenced through reference to NBC
A440S1 / E / Delete / Redundant; referenced through reference to NBC
CWC
Engineering Guide / -- / No change / Retained; referenced in a note.
CGSB
CAN/CGSB-1.501 / E / Delete / Redundant; referenced through reference to NBC
CAN/CGSB-12.1 / E / Delete / Redundant; referenced through reference to NBC
CAN/CGSB-55.33 / E / Delete / Redundant; referenced through reference to NBC
CAN/CGSB-51.34 / E / Delete / Redundant; referenced through reference to NBC
CGSB/ANSI/BHMA
CAN-CGSB-69.18-M90/ ANSI/BHMA A156.1-1981 / E/T / Delete “CAN-CGSB-69.18-M90/” / Withdrawn as a CGSB standard in 2003
T / Update reference to 2006 / Retained; not referenced in the NBC.
CGSB
CAN/CGSB-82.1 / E / Delete / Withdrawn; addressed by AAMA/WDMA/CSA-101/I.S.2/A440 which is referenced in the NBC
NRCC
NBC / T / Update reference to 2010
NLGA
Standard Grading Rules / E / Delete / Redundant; referenced through reference to NBC
ULC
CAN/ULC-S102 / E / Delete / Redundant; referenced through reference to NBC
CAN/ULC-S531 / E / Delete / Redundant; referenced through reference to NBC
CAN/ULC-S610 / E / Delete / Redundant; referenced through reference to NBC
3 / Definitions
Habitable room / E / Delete / Term not used in the standard
4 / General requirements
4.1 / Compliance
(heading) / E / Change heading from “Minimum requirements” to “Compliance / To more clearly reflect the content of the provisions
(provision) / T / Specify compliance with the NBC as the basic compliance requirement / See General Approach above. More and more requirements in the standard refer to the NBC or provide copies of NBC requirements. A single reference allows for deletion of multiple cross-references and copied requirements
Note (1) / E / Add note. / Explains that provisions in the standard are in addition or exceptions to the requirements of the NBC
Note (2) / E / Replace “Shall be considered” with “are” / Notes are not mandatory so mandatory language should not be used
E/T / Insert reference to the NBC / The note applies equally to the NBC.
Note (3) / E/T / Replace “quality of work” with “practice / “Quality” is undefined and open to interpretation.
4.2 / Construction Methods and Practice
(heading and provision) / E / Replace “quality of work” with “practice / “Quality” is undefined and open to interpretation.
(provision and Note) / E/T / Move the intent to a Note replacing “ensure” with “provide”. / “Durable” and “livable” are undefined so should not be specified in a requirement. Nothing can ever truly be “ensured.”
4.3 / Equivalence
4.3.1 / General / E / Delete “new” / Unnecessary; not clear if this is new rather than used or new as in innovative
preamble / E/T / Insert reference to the NBC / The provision applies equally to the NBC
T / Insert “achieve at least the minimum level of performance required by this standard and shall” / To state the basic criterion of achieving equivalent level of performance
Clause (a) / E / Move from preamble / Describes an option to testing.
4.3.2 / Test Procedures
--- / E / 1. Delete reference to Clause 4.1 / Unnecessary
E/T / 2. Change “structural” to “required” / Should apply to all equivalence testing not just structural.
T / 3. Insert “component” and “assembly” / Should apply to all elements of the building and its construction including, for example, windows, doors, walls, roofs.
4.3.3 / Independent testing
--- / E / Delete reference to Clause 5.1.3.1. Replace reference to 5.1.3.2 with 4.3.2. / Unnecessary or clause moved.
4.3.4 / Verification
(heading) / E / Add heading / To make information easier to find
(provision) / E / Replace “the CSA-Z240 MH Series of Standards” with “this Standard” / Does not apply to Z240.0.1. Reference in Z240.2.1. to other Standards in the Series applies the provision as applicable.
Note / E / 1. Replace “Clause” with “Section” / Consistent with correct terminology re. NBC structure
E / 2. Add “to requirements in the NBC” / To make clear that the requirements in the referenced provisions apply to the NBC requirements
4.2 / Minimum requirements
sentence 1 / E / Delete / Addressed in 4.1
sentences 2 and 3 / E / Delete / Provided in Note (2) to Clause 4.1
5 / Materials
(heading) / E / Insert heading / To make information easier to find
5.1 / Lumber
4.4.1 / Grading / E / Delete Clause and Table 1 / CSA O141 is in NBC by reference to NLGA
Re. Table 1, NBC does not differentiate based on width, and allows standard grade for all load bearing and utility grade for all non-loadbearing. There does not appear to be any reason for the more stringent requirements in Z240.
4.4.3 / Trusses / E / 1. Delete reference to testing / In NBC by reference to test standard.
E / 2. Delete sentence on equivalence / Alternatives must be in accordance with O86 in any case per NBC
6 / Structural design
6.1 / Compliance
(heading) / E / replace “General” with “Compliance” / To better identify the issue addressed by the clause
6.1.1 / Design and construction
(provision) / No change / First sentence is retained largely for information.
Second sentence needed to address in-transit loads
Note / E / Replace references to NBC and CWC Engineering Guide with reference to Clause 6.2.1 / NBC and CWC references covered by general reference to the NBC. Clause 6.2.1 addresses additional in-transit wind load.
5.1.2 / Structural members and their connections / E/T / Delete / Addressed by NBC.
5.1.3 / Equivalency of performance / E / Delete / All equivalency provisions provided in Clause 4.3.
Reference to engineering design redundant; provided in Clause 4.1
6.2 / Loads
Note / E / Delete / Referenced clause proposed to be deleted
5.2.1. / Floor loads / E / Delete / Addressed by general reference to NBC.
5.2.2 / Specified snow loads / E / Delete / Addressed by general reference to NBC.
6.2.1 / Wind Loads
6.2.1.1 / Wind loads on walls
(heading) / E / 1. Add heading / To make information easier to find
(preamble) / T / 1. Add “and constructed” / Home must be constructed to resist loads
T / 2. Replace “full design wind load of at least “ with “the greater design wind pressure of” / If the design wind load at the installation location is greater than 0.7 kPa, the home must be designed and constructed to the greater load.
E / 3. Change “load” to “pressure” / Consistent with accepted engineering terminology
Clause (b) / T / insert “the design hourly wind pressure at the installation site” / As above
6.2.1.2 / Wind loads on roofs
(heading) / E / 1. Add heading / To make information easier to find
(preamble) / T / 1. Add “and constructed” / Home must be constructed to resist loads
T / 2. Replace “full design wind load of at least “ with “the greater design wind load of” / If the design wind load at the installation location is greater than 0.7 kPa, the home must be designed and constructed to the greater load.
E / 3. Change “load” to “pressure” / Consistent with accepted engineering terminology
Clause (b) / T / insert “the design hourly wind pressure at the installation site” / As above
Note / E / insert Note / To explain the minimum stated design wind pressure
6.2.1.2 / Component fastening
E / Revise cross references
6.3 / Floor Deflection
(heading) / E / Revise to refer to floors / NBC reference addresses all other deflections
Note / E / Delete / Referenced Clause proposed to be deleted
6.3.1 / General
6.3.1.1 / Structural Members
(heading) / E / Delete / Not needed with deletion of clause 5.3.1.2.
(preamble) / E/T / Delete reference to engineering design and testing / Deflection limits apply regardless of design approach
(preamble and sub-clauses) / E/T / 1. Floors
- Replace “structural members” with “floor joists and floor trusses” and “L/240”
- Delete sub-clause (a) / Retain limit for floors only. Less stringent than NBC.
See below for roofs.
2. Roofs
- Delete sub-clauses (b) to (e) / Minimal differences with NBC
Roof beams and rafters
- 3 deflection limits consistent with NBC
- 1 limit more stringent
- 1 limit less stringent
Trusses
- differences only pertain to testing
- limits the same as NBC but NBC includes dead load
See “Z240 – Implications of Major Proposed Changes”.
Note (2) / E / Delete / Note does not explain exception for floors; NBC Part9 limit of L/360 applies to all cases including floors with no ceiling below.
5.3.1.2 / Subfloor / T / Delete / This deflection is excessive and does not reflect the material requirements for subfloors.
- 3 mm/16" o.c. = L/135
- 3 mm/24" o.c. = L/203
To achieve L/240, deflection would have to be limited to
- 1.7 mm @ 16” o.c. and
- 2.54 mm @24” o.c.
To achieve L/360
- 1.13 mm/16”
- 1.69 mm/24”
6.3.2 / Cantilever Assemblies
5.3.2.1 / Note / E / Replace clause with a Note / In NBC
6.3.2.1 / Prescriptive criteria for narrow units
(heading) / E / Add heading / To make information easier to find
E / Provide maximum unit width, minimum joist dimensions and grade, and maximum spacing in a list / To make finding information easier
6.3.2.2 / Performance criteria for longer cantilevers
(heading) / E / Add heading / To make information easier to find
No change to technical requirement / Retain to describe test criteria for acceptable alternative solution.
E / Insert reference to base requirements in the NBC / To make clear that the exception relates to both the NBC and Z240 requirements
6.4 / Anchorage of the home
(headings) / E / Add headings / To make information easier to find.
6.4.1 / Application
-- / E/T / Insert application statement / To make clear that the requirements apply only to homes on surface foundations
6.4.2 / Standard
-- / E/T / Change “geographical location of” to “site conditions at the installation location for” / To make clear that the conditions at the specific installation site are of concern
6.4.3 / Attachment
(heading) / E / Add heading
6.4.4 / Instructions, fittings and fixtures