CHAPTER 4-02
INTERNATIONAL RESIDENTIAL CODE
Sections:
4-02-001-0001 AMENDMENTS, ADDITIONS, AND DELETIONS
4-02-001-0001 AMENDMENTS, ADDITIONS, AND DELETIONS
The following provisions shall have the effect of either amending, adding to, or deleting from the International Residential Code adopted in Flagstaff City Code, Title 4, Building Regulations, Chapter 4-01, Administrative Enactments, Section 4-01-001-0002, Adoption.
CHAPTER 3, IRC, BUILDING PLANNING
Revise the amendment to Section R325, Manufactured Housing Design Requirements, as follows:
All new manufactured housing (housing classified as modular, factory built or manufactured house) installed within the City of Flagstaff will be designed to meet HUD minimum standards. The City of Flagstaff enforces a 40 pounds per square foot roof snow load for site built construction. HUD standards for snow winter areas in Arizona are not consistent with local conditions and owners should be aware of the differences.
For "used" manufactured housing or "resale"/relocated manufactured housing being brought into the City of Flagstaff, the following applies. As per direction from the State of Arizona, Office of Manufactured Housing, A.R.S. Title 41, specifically requires that all manufactured housing units be certified to meet the minimum standards of the United States Department of Housing and Urban Development and are to be designed in accordance with consistent State of Arizona Standards for manufactured homes and related industries. An applicant requesting an installation permit and inspection will be required to provide proof to the Building Official of the current State certification or re-certification of the unit.
Amend Section R309.5, Fire Sprinklers, by deleting entire section.
CHAPTER 4, IRC, FOUNDATIONS
Revise the amendment to Section R401.4.1 as follows:
All new residential subdivisions require a geotechnical soils report be prepared with foundation recommendations. In established areas of the City of Flagstaff, "in-fill" or vacant lots in subdivisions established prior to 1996, the designer may use 1500 pounds per square foot. Where the Building Official determines that in-place soils with an allowable bearing capacity of less than 1500 pounds per square foot (psf) are likely to be present at the site, then allowable bearing capacity shall be determined by a geotechnical investigation at the expense of the permit applicant.
Amend R403.1 by adding:
All footings located less than 18 inches (457 mm) below existing grade to be air entrained, 3,500 psi concrete (severe weather), and pinned to rock at intervals specified for foundation wall vertical reinforcements or as specified by the Arizona design professional.
Revise the amendment to R403.1.1 by deleting the following language:
Spread footings shall be at least 8 inches (204 mm) in thickness. Footing projections, P, shall be at least 4 inches (102 mm) and shall not exceed the thickness of the footing.
Amend R403.1.2 and R403.1.3 by adding:
Add Seismic "C" category to both sections at all seismic D1 and D2 locations.
Amend R403.1.3 by deleting the exception.
Amend Table R403.1 by changing:
All references to 1,500 and 2,000 psf Load Bearing columns shall be changed from 12 inch (305 mm) and 15 inch (383 mm) minimum width of concrete or masonry footings to 16 inch (408 mm) minimum width for one and two story convention light-frame construction and one story under 4-inch brick veneer and 8-inch solid or fully grouted masonry structures.
Delete R403.1.3.1 in its entirety and add the following language to the replacement amendment:
Foundations with stem-walls shall be provided with a minimum of one No. 4 bar at the top of the wall and two No. 4 bar at the bottom of the footings equally spaced.
Exception: Footing designs without reinforcing steel must be "sealed" by a certified or registered Design Professional.
Delete Section R403.3 in its entirety.
Amend R404.1.1, R404.1.2, R404.1.4, and R404.1.8 by adding:
Add Seismic Design Category "C" to all references of D1 and D2.
Amend R404.1.4, Number 1, by deleting "in the upper 12 inches of the wall" and adding:
1. Minimum reinforcement shall consist of one No. 4 horizontal rebar located at top of wall not more than 5 inches (128 mm) below the finished concrete and at the top course of concrete masonry unit walls within close proximity to the anchor bolts.
Amend R404.1.4, second paragraph, by changing:
Change the vertical reinforcement bar reference from #3 rebar to #4 rebar.
Amend R407.3, Exception, by deleting:
Delete Seismic Design Category "C" from this exception.
CHAPTER 6, IRC, WALL CONSTRUCTION
Amend R602.5 by adding:
Ladder backing shall be spaced a maximum 8 inches (204 mm) on center.
CHAPTER 9, IRC, ROOF ASSEMBLIES
Revise the amendment to Section R904.2 as follows:
All roofing materials used must be a class "A" or "B" and rolled roofing is to be a Class A or B material and shall be a self-adhering, polymer modified bitumen material.
Delete Sections R905.7 and R905.8 in their entirety.
CHAPTER 11, IRC, ENERGY EFFICIENCY
Amend Section N1102.1 by adding:
Section N1102.1.1. Insulation values in 2x6 wall construction will remain the same at R-19. Insulation values in 2x4 wall construction will remain at R-15 (high density). Construction using Structural Insulated Panels (SIPS) and/or straw bale in-fill methods will be a minimum of R-21 (industry standards often show results of R-30 to R-45 depending upon materials and thickness of the wall).
Amend Section N1102.1.2 by adding:
Section N1102.1.2.1. All new construction and replacement windows to have National Fenestration Rating Council (NFRC) total unit U-factor of 0.45 or less. Windows shall also be low-E where practical (not recommended for southern exposures) or not being used for solar heat gain to fuel a solar massing device.
Amend Section N1103 by adding:
Section N1103.7 Furnaces: All furnaces installed in new construction shall be 90% condensing type furnaces.
Exception: Replacement furnaces are to be voluntary 90% condensing type furnaces.
Amend Section N1105 by adding:
Section N1105.10 Dual Plumbing. All new residential single family detached units are "voluntarily" requested to install the piping only for dual plumbed for "gray water" disposal and conservation efforts. Access for future valving must be provided. The initial installation will be connected to sanitary sewer. The piping shall be installed in accordance with Chapter 13, Gray Water Recycling Systems, of the International Plumbing Code, 2012 Edition, and the regulations established by ADEQ. Reference Type 1 General Permit Best Management Practices for the 13 points of using gray water, at www.adeq.state.az.us or call at 1-800-234-5677.
CHAPTER 13, IRC, GENERAL MECHANICAL
Revise the amendments to Section M1305.1.4.3 by adding the following language:
Furnaces are to be hard-wired (no cord & cap unless specifically supplied by the manufacturer) with a 20 ampere motor rated disconnect within sight of the furnace.
Revise the amendment to Section M1307.3.1 to read:
See G2408.3 for appliance protection.
Amend Section 1507.1 by deleting "or whole-house mechanical ventilation," from the first sentence.
Amend Section 1507.3, Whole-house mechanical ventilation system, by deleting in its entirety.
CHAPTER 24, IRC, FUEL GAS
Amend Section G2406.2 by deleting numbers 3 and 4.
Change the amendment to Section G2408.3 to read as follows:
Appliances shall not be located in a location where subject to mechanical damage unless protected by approved barriers such as steel bollards filled with concrete, poured in place concrete curb, or installed wheel stops, or on a platform with a minimum clearance of 24 inches (460 mm) above the floor. Appliances not subject to mechanical damage shall be installed per Section 305.3. The exception is deleted in its entirety.
Change the amendments to Sections G2417.4.1 and G2417.4.2 by making the following revisions:
The test pressure shall be 10 psi (or half the maximum of the gauge) for a period of 15 minutes. Gauges shall be of 1/10 pound increments or less and shall have a pressure range no greater than twice the test pressure.
In Section G2439.4 (614.5), Makeup Air, change the amendment to read as follows:
Installations exhausting more than 200 cfm (0.09 m3/s) shall be provided with makeup air.
CHAPTER 26, IRC, GENERAL PLUMBING REQUIREMENTS
Revise the amendment to Section P2603.6.1 to read as follows:
Building sewers that connect to private sewage disposal systems must be approved by the Coconino County Environmental Health Department. Building sewers for single family detached buildings shall be a minimum of 18 inches (306 mm) below grade.
CHAPTER 29, IRC, WATER SUPPLY AND DISTRIBUTION
Amend Section P2303.5.1 by deleting the words "other than plastic," in the first sentence.
Amend Section P2904, Dwelling Unit Fire Sprinkler Systems, by deleting section in its entirety.
CHAPTER 31, IRC, VENTS
Revise the amendment to Section P3101.1, Roof Extension, to read as follows:
Add "12 inches (306 mm) above the roof."
INTERNATIONAL RESIDENTIAL CODE (IRC), 2012 EDITION, PART X – APPENDICES
Revise the amendments to Part X - Appendices as follows:
APPENDIX F – Radon Control Methods
APPENDIX G – Swimming Pools, Spas and Hot Tubs
APPENDIX H – Patio Covers
APPENDIX J – Existing Buildings and Structures.
APPENDIX M – Home Day Care, R-3 Occupancy (a home occupation permit is required prior to receiving any building permits for conversions or improvements).
APPENDIX O – Gray Water Recycling Systems (cross reference to Chapter 11 and timing for implementation. Applicant must also meet the requirements of ADEQ if systems are larger than what the State of Arizona allows).
APPENDIX R – Straw Bale construction guide for residential use.
Section AR101 TITLE, SCOPE and PURPOSE
AR101.1 Title. These provisions shall be known as the City of Flagstaff Straw Bale Construction Code.
AR101.2 Scope. This appendix shall govern the use of baled straw as a building material, and shall apply to Group R occupancies, Group U occupancies and other occupancies when secondary and appurtenant to Group R or Group U occupancies. Unless stated otherwise in this appendix, all other provisions in this code shall apply to structures using baled straw as a building material.
AR101.3 Purpose. The purpose of this appendix is to provide minimum requirements specific to alternative building materials, reference Section R104.11 and associated testing in Section R104.11.1 Tests, with regards to using straw bale as a building material. With the provisions of this appendix, straw bales may be used as a structural or non-structural material. Structural uses include elements designed to support gravity loads, and elements design to resist in-plane wind and seismic loads. Non-structural uses include, but are not limited to, infill walls, insulation, landscape walls and benches.
AR101.3.1 Current test studies done by Bou-Ali, Ghailene (1993), University of Arizona, Tucson; Ruppert, Grandsaet (1999), University of Colorado, Boulder; show that structurally bearing elements of straw bale are limited to between 300 - 800 pounds per linear foot depending upon the wall plaster used. The CBC also limits the walls to 20 PSF snow live loads.
AR101.3.2 For Flagstaff, with a 40 PSF snow load, the bearing capacity shall be limited to 150 - 400 pounds per linear foot. No floor loading will be allowed on straw bale walls without structural engineering.
AR101.3.3 Trussed roof spans are limited to fifteen (15) feet in width and top plates and anchoring for uplift must be provided. All other spans or sections of a house which would be two story or more must use a structural "space" frame or post and beam method. In these designs, the straw bale is being used as infill for insulation value.
Section AR102 DEFINITIONS
AR102.1 General. The following words and terms shall, for the purposes of this appendix, have the meanings shown here. Refer to Chapter 2 for general definitions used elsewhere in the International Residential Code.
Bale. Equivalent to "straw bale" for the purposes of this appendix.
Bending. A moment (force) acting on a body will induce bending stress.
Bond. The measure of adhesion; i.e., the bond of concrete or stabilized earth to reinforcing bars and anchor bolts.
Bond Beam. A structural element within a wall (usually at the top) intended to stabilize the wall and facilitate the transfer of loads from above.
Buckling. The collapse of a wall or column by bending and breaking under a vertical load.
Flake. A slab or straw removed from an untied bale. In particular, an intact slab (3-5" thick) as created by the baling machine.
Laid flat. Stacking bales so the sides and the largest area are horizontal and the longest dimension of this area is parallel with the wall plane.
Laid On-Edge. Stacking bales so the sides with the largest area are vertical and the longest dimension of this area is horizontal and parallel with the wall plane.
Mesh. An openwork fabric of linked strands of metal, plastic or natural fiber, embedded in plaster to provide tensile reinforcement and/or bonding. (also sometimes lath).
Moisture Barrier. A continuous barrier capable of stopping the passage of water.
Non-Load-bearing. (See Non-Structural.)
Non-Structural. A straw bale wall or other element which supports only its own weight, and may resist out-of-plane lateral loads.
Pins. Metal rod, wooden dowel or bamboo driven into or secured on the surface of stacked bales for purposes of connection or stability.
Plaster. Gypsum, lime, lime-Cement, or cement plasters, as defined by the code and Section AR106 of this appendix, or clay plaster and earth-cement plaster as defined in Section AR106.9 and AR106.10.
Running Bond. The placement of straw bales such that the head joints in successive courses are offset at least one quarter of the bale length below.
Skin. The compilation of plaster and reinforcing, if any, on the surface of stacked bales.
Structural. A straw bale wall or other element which supports gravity loads (dead and live) and/or resists in-plane lateral loads.
Stack Bond. The placement of straw bales such that head joints in successive courses are vertically aligned (similar to the "soldier" courses in masonry construction).
Straw. The dry stems of cereal grains left after the seed heads have been substantially removed.
Straw Bale. A rectangular compressed block of straw, bound by polypropylene strings or baling wire.
Straw-bale. The adjective form of straw bale.
Straw-clay. A mix of loose straw and clay binder.
Three-String Bale. A straw bale bound by three strings or wires. Typically with approximate dimensions of 15"x23"x42" to 48" long.
Truth Window. An area of a straw-bale wall left without its finish, to allow view of the straw otherwise concealed by its finish.
Two-String Bale. A Straw bale bound by two strings or wires. Typically with approximate dimensions of 16" or 14" x 18" x 36" to 45" long.
Vapor-Permeable Membrane. A material or covering having a permeance rating of five (5) perms or grater, when testing in accordance with the desiccant method using Procedure A of ASTM E96. A vapor-permeable material permits the passage of moisture. (This definition is shown for convenience and is identical to that shown in Chapter 2, 2012 IBC.)
Vapor Retarder. A vapor-resistant material, membrane or covering such as foil, plastic sheeting or insulation facing having a permeance rating of one (1) perm or less, when tested in accordance with the desiccant method using Procedure A or ASTM E96. Vapor retarders limit the amount of moisture vapor that passes through material or wall assembly. (This definition is shown for convenience and is identical to that shown in Chapter 2, 2012 IBC.)
Section AR103 BALES
AR103.1 Bales Shall Be Rectangular In Shape. The use of non-rectangular bales, such as circular bales, shall not be used in structural applications.
AR103.2 Size. Bales used with a continuous wall shall be of consistent height and width to ensure even distribution of loads with the wall system.
AR103.3 Ties. Bales shall be bound with ties of polypropylene string or baling wire. Bales with broken or loose ties shall be firmly retied. A visual check by the assigned field inspector of materials delivered to the job site will be done prior to assembly of bale walls.
AR103.4 Moisture Content. The moisture content of bales, at the time of procurement and at the time of application of the first coat of plaster or installation of another weather protective finish, shall not exceed nineteen (19%) percent of the total weight of the bale (ideal moisture content would be the same as kiln dried wood, between 15-17%). The moisture content of bales shall be determined by use of a moisture meter designed for use with baled straw or hay, equipped with a probe of sufficient length to reach the center of the bale. A minimum of five bales, selected by the inspector at random will be tested.
AR103.5 Density. Bales shall have a minimum dry density of 6 pounds per cubic foot. The dry density shall be determined by reducing the actual bale weight by the weight of the moisture content in pounds, and dividing by the volume of the bale in cubic feet. At least five bales and not less than two (2) percent, randomly selected from the bales to be used, may be tested to determine if all of the bales for the building are of acceptable density. This inspection will be done at the same time as the moisture content is done. If equipment is not available, then the builder may elect to use a third party or special inspection to perform the testing.
AR103.6 Partial Bales. Custom-made partial bales shall be firmly retied and where possible, use the same number of ties as the standard size bales.
AR103.7 Types of Straw. Bales of various types of straw, including wheat, rice, rye, barley, oat and similar grain plants, shall be acceptable if they meet the minimum requirements of this Section for density, shape, moisture content and ties. Bales of hay and other grasses containing seed shall not be used as a building material. When securing materials from a supplier, it is practical to remember that straw is for building and hay is for food.
AR103.8 Protection of Bales Prior To Installation. The builder must store the bales in such a manner as to protect them from weather and other sources of moisture damage. Storing bales in direct contact with the earth or uncovered during inclement weather will be subject to rejection by the building inspector.
AR103.9 Unacceptable Bales. Bales which show signs of damage due to moisture, including but not limited to mold or fungus growth or associated discoloration, even if they are of an acceptable moisture content and density, shall not be used. The builder must inspect all deliveries and protect the bales prior to the installation in the wall frames.
AR103.10 Wall Thickness. Nominal minimum bale wall thickness shall be fourteen (14") inches or greater.
Section AR104 MOISTURE
AR104.1 General. All weather-exposed bale walls, other weather-exposed bale elements and bale walls enclosing showers or steam rooms shall be protected from water damage.
AR104.2 MOISTURE CONTENT of BALES (See definitions, Section AR103.4).
AR104.3 Moisture Barriers and Vapor Retarders. Plastered bale walls may be constructed without any membrane barrier between straw and plaster, except as required elsewhere in this appendix. This is allowed to facilitate transpiration of moisture from the bales and to secure a structural bond between straw and plaster. No vapor permeance rating of less than 5 perms, except as permitted elsewhere in this appendix, or as demonstrated to be necessary by a design professional of record (this must be an Arizona Registered Architect or Engineer in accordance with ARS 32-121)shall be used.
AR104.4 Horizontal Surfaces. Bale walls and other bale elements shall have a moisture barrier at all horizontal surfaces exposed to the weather. This moisture barrier shall be of a material and installation that will prevent water from entering the wall system or other bale elements.
AR104.4.1 These horizontal surfaces include, but are not limited to exterior window sills, sills at exterior niches, bale vaults and arches, tops of landscape walls and weather-exposed benches.
AR104.4.2 The finish material at all "horizontal" surfaces shall be sloped a minimum of one inch per foot (8%) and shall drain beyond and away from all bale walls or bale elements. If the moisture barrier is below the finish material, it shall be sloped a minimum of one inch per foot (8%) and shall drain beyond the outside vertical surface of the bale's vertical finish.
AR104.4.3 In areas where snow may collect, the moisture barrier and/or flashing element may have to be extended upwards on the vertical surface to prevent damage to the bale(s).
AR104.5 Parapets - Prohibited Construction. Parapets made of straw bales are prohibited. The roof over-hang must always extend over the top of the straw bale walls.
AR104.6 Bale/Concrete Separation. There shall be a moisture barrier and a capillary break between bales and support concrete. The moisture barrier may be of any durable sheet or liquid applied membrane that is impervious to water. The capillary break may be any material that prevents the "wicking" of moisture across the material and into the bale(s). Where bales abut a concrete or masonry wall that retains earth, there shall be a moisture barrier between the wall and the bales.
AR104.7 No Plumbing Trees Will Be Allowed in Straw Bale Walls. Conventional framed walls will be provided. Plumbing will not be installed in interior non-load bearing straw bale walls. The use of wood framed "false" walls or furred out sections in front of walls will be allowed.
AR104.7.1 Exception: Hose bibs will be allowed to penetrate a straw bale exterior wall as long as the plumbing is sleeved and the bib/sleeve extends a minimum of six (6") inches beyond the exterior/interior surfaces of the wall.
Section AR105 STRUCTURAL USE OF STRAWBALE
AR105.1 Scope. Buildings constructed with straw bales shall comply with this Section, and with all other structural provisions of the International Residential Code, 2012 Edition, Chapters 4, 5, 6 (as it pertains to those areas of a straw bale structure which is conventionally framed) and 8, unless stated otherwise in this appendix. The design considerations for Flagstaff, Arizona are found in Table R301.2(1) as amended in Title 4, City Codes, City of Flagstaff 2011 Building Code Amendments.
AR105.1.1 Energy Considerations. The use of straw bale construction may enable the builder to meet or surpass many of the requirements of the International Energy Conservation Code (IECC).
AR105.2 General. Straw bale buildings may use any type of structural system allowed by this code and this appendix.
AR105.3 Foundations. Foundations for straw bale walls and other straw bale elements may be of any foundation type permitted by this code and amendments thereto. The frost depth requirements remain the same at 30" below finished grade. The amount of steel will remain the same at two (2), #4 rebar laid continuously at the bottom of the footing (three inches above the bottom of the footing). The straw bales may not be buried below finished grade and the first row must be placed a minimum of six (6) inches above the finished grade on a concrete slab (see detail).
AR105.4 Alternative Foundations. Alternate foundations and foundation systems may be used if designed by an Arizona Registered design professional (Architect or Engineer).
AR105.6 Configuration of Bales. Bales may be laid flat or on-edge as limited in height by AR105.5. Bales in walls with reinforced plasters may be a running or stack bond. Bales in walls with un-reinforced plaster shall be in a running bond only.
AR105.7 Pre-Compression of Straw bale Walls.
AR105.7.1 When not required:
AR105.7.1.1 For non-structural walls.
AR105.7.1.2 For walls designed or allowed to resist lateral forces only.
AR105.7.1.3 For walls bearing gravity roof loads, when the full dead load of the roof is imposed and remains on the wall for at least 28 days before plastering. No design snow load greater than 40 psf is allowed (see restrictions on spans in Section AR101.3.3). No floor loads may be supported by walls which are not pre-compressed.
AR105.7.2 When required. All walls bearing gravity loads, which are not described in AR105.6.1, shall be pre-compressed to a force equal to or greater than the design loads on the wall.
AR105.8 Voids and Stuffing. Voids in the field of structural straw bale walls shall be limited to six (6) inches in width and shall be firmly stuffed with flakes of straw or with straw-clay, before the application of plaster.
AR105.9 PLASTER SKINS.
AR105.9.1 General. Plaster skins on structural walls may be of any type allowed in Section AR106, except gypsum plaster, and shall also be limited by Table AR105-A and Table AR105-B.
AR105.9.2 Straightness. On structural walls (load bearing), plaster skins shall be straight as a function of the bale wall surface they are applied to as follows:
AR105.9.2.1 Across the face of the bale - straw bulges shall not protrude more than 3/4" across two feet of its height or length.
AR105.9.2.2 Across the face of a bale wall - straw bulges shall not protrude from the vertical plane of the bale wall more than 2-1/2" over eight (8) feet.
AR105.9.2.3 Offset of bales - the vertical face of adjacent bales may not be offset more than 3/4".
AR105.9.3 Plaster and Membranes. Structural bale walls shall have no membrane between straw and plaster; or shall have sufficient attachment through the bale wall from one plaster skin to the other as designed by an Arizona Registered design professional (Architect or Engineer). See sections AR106.5 and AR106.6.
AR105.10 Transfer of Loads into Plaster Skins. When plastered straw bale walls are used to bear gravity and/or lateral loads, such loads shall be transferred into the plaster skins by direct bearing or by other adequate transfer mechanism (alternatives must be provided to the Building Official for approval).
AR105.11 SUPPORT of PLASTER SKINS.
AR105.11.1 For Structural Walls. Plaster skins for structural straw-bale walls shall be continuously supported along their bottom edge to allow a load path into the foundation system. Acceptable supports include, but are not limited to: concrete or masonry footings, concrete slab, wood framed flooring which is adequately blocked for the width of the imposing load, wood beam or steel angle adequately anchored for the imposed weight of the plaster skin.
AR105.11.2 For Non-Structural Walls. Plaster skins for non-structural walls need not to be supported along their bottom edge. Maximum length of walls without cross bracing (either straw bale or conventional framing) is twenty (20) feet.
|
WALL PLASTERa |
SILL PLATESbc |
Anchor, Bolts or Other Sill Fasteningc |
Meshd |
Staples |
Allowable Bearing Capacityh |
|---|---|---|---|---|---|
|
A. Clay |
c |
c |
None P |
None P |
300 |
|
B. Soil-Cementk |
c |
c |
d |
e,f,g |
800 |
|
C. Lime |
c |
c |
d |
e,f,g |
450 |
|
D. Cement-lime |
c |
c |
d |
e,f,g |
800 |
|
E. Portland Cementh |
c |
c |
d |
e,f,g |
800 |
a Plasters shall conform with AR106.9 through AR106.11.2.3 for makeup and thickness with AR10.92 for straightness and with AR105.11.1 and AR105.11.2 for support of plaster skins.
b Sill plates shall support and be flush with each face of the bale wall.
c For walls supporting gravity loads only (or for non-structural walls), use sill plates and fasteners as required for framed walls in 2308.2 and 2308.3. See table AR 105-B for requirements for shear walls and braced panel walls.
d May be any metal mesh allowed by this code and must be installed throughout the plaster with minimum four (4") inch laps. Fasten with staples per footnote "e". Staples shall be at maximum spacing of two (2") inches o.c. to roof or floor bearing assembly, or as shown necessary to transfer loads into the plaster skins per AR105.10 and at a maximum spacing of four (4") inches o.c. to sill plates.
e Staples shall be gun staples (stainless steel or electro-galvanized, 16 gauge with 1-1/4" legs, 7/16" crown) or manually driven staples (galvanized 15 gauge with 7/8" legs, 3/16" inner spread and rounded shoulder). Other staples may be used as designed by an Arizona Registered design professional.
f Staples shall be firmly driven, diagonally across mesh intersections at spacing indicated. For walls with a different plaster on each side, use the lower value.
g For walls with a different plaster on each side, use the lower value.
h Minimum 1-1/2" thickness. Building Official may require a compression test to demonstrate a minimum 100 psi compressive strength.
i Except as necessary to transfer roof or floor loads into the plaster skins per AR105.10.
j Minimum 1-1/2" thickness. Building official may require a compression test to demonstrate a minimum 1000 psi compressive strength.
k Containing lime as described in AR106.11.
|
Wall |
Plastera (both sides) |
Sill Platesb |
Anchorc Bolts (on center) |
Meshd |
Staplesefg (on center) |
Allowable Shearhi |
|---|---|---|---|---|---|---|
|
A1 |
Clayi |
2x4 |
2'8" |
None |
None |
100 |
|
A2 |
Clayi |
2x4 |
2'8" |
3"x3" knotted hemp |
3" |
120 |
|
A3 |
Clayi |
4x4 |
2'0" |
2"x2" high-density polypropylene |
2" |
180 |
|
B |
soil-cementi |
4x4 |
2'0" |
2"x2" 14 gak |
2" |
300 |
|
C1 |
lime |
2x4 |
2'8" |
17 ga. woven wire |
2" |
200 |
|
C2 |
lime |
4x4 |
2'0" |
2"x2" 14 gak |
2" |
250 |
|
D1 |
cement-lime |
4x4 |
2'8" |
17 ga. woven wire |
2" |
400 |
|
D2 |
cement-lime |
4x4 |
2'0" |
2"x2" 14 gak |
2" |
450 |
a Plasters shall conform with AR106.9 through AR106.11.2.3 for makeup and thickness, with AR105.9.2 for straightness and with AR105.11 for support of plaster skins.
b Sill plates shall be pressure treated or foundation red wood.
c Anchor bolts shall be 1/2" diameter with washers with a minimum seven (7") inch embedment in the concrete foundation.
AR105.11.2 Resistance to out-of-plane lateral loads. Plastered straw bale walls are capable of withstanding out-of-plane design loads prescribed in this code with the following limitations:
AR105.11.2.1. Walls with reinforced plasters shall be limited by a 6:1 ratio of stacked bale height to bale width per AR105.5 (this limits the 23 inch wide bale to 11'-6" in height and 18" inch wide bales to 9' in height).
AR105.11.2.2 Walls with un-reinforced plasters shall be limited by a 4:1 ratio of stacked bale height to bale width (this limits the 23 inch wide bale to 7'-8" and the 18" inch wide bales to 6' in height). Walls may not be built using the overall length of the bale (often 36 to 48" in length to increase the height). An exception can be made for custom made bales if the ratios of height, width and length are maintained. Regardless, no straw bale walls will be allowed to be greater than fourteen (14') feet in height without (1) being engineered by an Arizona Registered design professional or (2) being part of a post and beam structure in which the straw bales are only used as in-fill.
AR105.11.2.3 Wall with un-reinforced plasters or no plaster, and with internal or external pins, shall be limited by a 6:1 ratio of stacked bale height to bale width. Pins may be 1/2" diameter steel (# 4 rebar), wood or bamboo. Internal pins shall be installed vertically at a maximum of two (2') foot spacing into the bales from the top course to bottom course, with the bottom course being connected to its support similarly with pins or other approved means. Pins may be continuous or may overlap through one bale course. External pins shall have full lateral bearing on the sill plate and the roof or floor bearing member and shall be tightly tied through the wall to an opposing pin with polypropylene string or bailing wire at a thirty (30") inch maximum spacing.
AR105.11.3 PRESCRIPTIVE DESIGN USING STRUCTURAL STRAW BALE WALLS.
AR105.11.3.1 General. Plastered straw bale walls may be used structurally, without design by an Arizona design professional (Architect or Engineer), as described in this subsection. Such walls shall also comply with AR105.5 through AR 105.11.2.3 of this Section and shall comply with other Sections of this appendix as applicable.
AR105.11.3.2 Load and Other Limitations. As described in 2308.2-3 through 7, and 2308.2.2.
AR105.11.3.3 Gravity Load Bearing Walls. Limited to wall types B, C, D and E, shown in Table AR105-A. Type A walls may be used if they are demonstrated to support design loads no greater than the allowable load.
AR105.11.3.4 Braced panels. Straw bale shear walls may be used as braced panels per the requirements and limitations in IBC Section 2308.9.3 Bracing, and per IBC Section 2308.12. Additional requirements for conventional construction in Seismic Design Category C. Straw bale shear wall types B, C, D and E shown in Table AR105-B may be used in situations where braced wall panel types 2, 3, 4, 6 and 7 are allowed. Straw bale shear wall type A may be used in situations where braced wall panels types 1 and 5 are allowed.
AR105.12 Connection of Framed Walls to Straw bale Walls. Framed walls perpendicular to or at an angle to a straw bale wall assembly, need only be fastened to the bottom and top wood members of the straw bale wall per framing connections permissible in this code. Where such connection is not possible, the abutting stud shall be connected to alternating straw bale courses with a 1/2" diameter steel (#4 rebar), wood or bamboo dowel with minimum of eight (8") penetration into the straw bale.
AR105.13 Alternate Performance Design Criteria (must provide structural calculations and be stamped by an Arizona Registered design professional). When plastered straw bale walls or other elements are engineered, they may use the model of retained, thin shell, reinforced concrete, as in the American Concrete Institute's ACI-318 Manual. This model may be used for all reinforced plasters, including those without cement. Such design and analysis shall be made in accordance with the following:
AR105.13.1 General. Straw bale structural systems and elements shall be designed using engineering principles, fundamental engineering behavior and principles of mechanics.
AR105.13.2 Rationality. Straw bale structural elements shall be designed based on a rational analysis in accordance with established principles of mechanics. These elements shall provide a complete load path capable of transferring all loads and forces from their point of origin to the load-resisting elements based on a rational connection of components.
AR105.13.3 System Characteristics. Strength, stiffness and toughness (ductility) characteristics or the bales and their skins shall be considered in the design of the system.
Section AR 106 FINISHES
AR106.1 General. Finishes applied to straw bale walls may be of any type permitted by this code and shall comply with this Section and the provisions of Chapter 14 (Exterior Walls, 2012 IBC) and Chapter 25 (Gypsum Board and Plaster, 2012 IBC) unless stated otherwise in this Section.
AR106.2 Purpose and Where Required. Straw bale walls and other straw bale elements shall be finished so as to provide mechanical and fire protection of the bales, restrict the passage of air through the bales and to protect them from weather.
AR106.3 Vapor Retarders. No vapor retarder may be used on a bale wall, nor shall any other materials be used which has a vapor permeance rating of less than 5 perms; except as permitted elsewhere in this appendix or as demonstrated to be necessary by an Arizona Registered design professional (Architect or Engineer).
AR106.4 Plaster. Plaster applied to bales may be of any type described in this section.
AR106.5 Plaster and Membranes. Plaster may be applied directly to straw bale walls and other straw bale elements, in order to facilitate transpiration of moisture from the bales and to secure a mechanical bond between the skin and the bales; except where a membrane is allowed or required elsewhere in this appendix. Structural bale walls shall have no membrane between straw and plaster or shall have sufficient attachment through the bale wall from one plaster skin to the other, as designed by an Arizona Registered design professional (Architect or Engineer).
AR106.6 Lath and Mesh for Plaster. In straw bale construction the surface of the straw bales functions as lath and no other lath or mesh is necessary; except as required for tensile strength of the plaster and/or wall assembly in particular structural applications (see AR105). Straw bales laid flat or on-edge provide a sufficient mechanical bonding surface between plaster and straw.
AR106.7 Plaster on Non-Structural Walls. Plaster on walls that do not carry gravity loads and are not designed to resist in-plane lateral forces, may be any plaster as described in this Section.
AR106.8 Plaster on Structural Walls. Plaster on structural walls shall comply with AR105.9 through AR105.11. Plaster on walls that carry gravity loads shall comply with Table AR105-A. Plaster on walls designed to resist in-plane lateral forces, shall comply with Table AR105-B.
AR106.9 Clay Plaster (Also known commonly as earth or earthen plaster).
AR106.9.1 General. Clay plaster is any plaster whose binder is comprised primarily of clay. Clay plasters may also contain sand or other inert granular material and may contain reinforcing fibers. Acceptable reinforcing fibers include, but are not limited to, chopped straw, hemp fiber, nylon fiber and animal hair.
AR106.9.2 Mesh. Clay plaster may have no mesh.
Exception: A natural fiber mesh, corrosion-resistant metal mesh or high-density polypropylene mesh may be used.
AR106.9.3 Thickness. Clay plaster shall be a minimum one (1") inch thick, unless required to be thicker for structural or fire-resistance as described in this appendix.
AR106.9.4 Rain-Exposed. Clay plaster, where exposed to rain (snow) shall be finished with lime plaster or other erosion resistant finish.
AR106.9.5 Prohibited Finish Coat. Cement plaster and cement-lime plaster are prohibited as a finish coat over clay plasters.
AR106.9.6 Additives. Additives may be used to increase the plasters workability, durability, strength or water resistance.
AR106.9.7 Separation of Wood and Clay Plaster. No separation or moisture barrier is required between untreated wood and clay plaster. (Wood, earth and foundation separation requirements are still enforced and covered in Section R319 and R403 of 2012 IRC).
AR106.10 Earth-Cement Plaster (also known commonly as soil-cement, stabilized earth or pise').
AR106.10.1 General. Earth-cement plaster is comprised of earth (free or organic matter), Portland cement and may include sand or other inert granular material. May contain reinforcing fibers.
AR106.10.2 Mesh. Earth-cement plaster shall use any corrosive-resistant metal mesh permitted by this code and as described in Section AR105 if used on a structural wall.
AR106.10.3 Thickness. Earth-cement plaster shall be a minimum of 1-1/2" thick.
AR106.11 Gypsum Plaster.
AR106.11.1 General. Gypsum plaster shall comply with Section 2511 of the 2012 IBC.
AR106.11.2 Restriction of Use. Gypsum plaster is limited to use on interior surfaces and on non-structural walls, except as a finish coat over an allowed structural plaster.
AR106.12 Lime Plaster.
AR106.12.1 General. Lime plaster is any plaster whose binder is comprised primarily of calcium hydroxide (CaOH). This includes Type N or Type S hydrated lime, natural hydraulic lime or quicklime. Lime plasters shall comply with ASTM Standards C5 and C206. The plaster may be applied in two coats, provided that the combined thickness is at least 7/8" thick and each coat is not greater than 5/8" thick. The combined thickness of all plaster coats (regardless of numbers) shall be no more than 1-1/2" thick.
AR106.13. Cement-Lime Plaster.
AR106.13.1 General. Cement-lime plaster shall comply with Section 2508 of the 2012 IBC, except that the plaster may be applied in two (2) coats, provided that the combined thickness is at least 7/8" thick and each coat is no greater than 5/8" thick.
AR 106.14 Portland Cement Plaster.
AR106.14.1 General. Portland cement plaster shall comply with Section 2512 (2012 IBC) of this code, except that the amount of lime in all plaster coats shall be a minimum of one (1) part lime per six (6) parts cement so as to allow a minimum acceptable vapor permeability. The plaster may be applied in two (2) coats, provided that the combined thickness is at least 7/8" thick and each coat is not greater than 5/8" thick. The combined thickness of all plaster coats (regardless of numbers) shall be no more than 1-1/2" thick.
AR106.15 Alternative Plasters. Plasters or variations of plasters, which do not fit in any other category described in this Section, may be allowed if such plasters are demonstrated to be appropriate for the particular application. Approval shall be made by the Building Official.
AR106.16 Finishes Over Plaster. Other finishes, as permitted elsewhere in this code, may be applied over the plaster, except as prohibited in Section AR106.17.
AR106.17 Prohibited Plasters and Finishes. Any plaster or finish with a cumulative perm rating of less than 5 perms is prohibited on straw bale walls or other bale elements, unless demonstrated to be necessary by the Arizona Registered design professional (Architect or Engineer).
AR106.18 Separation of Wood and Plaster. Where wood framing or wood sheathing occur in straw bale walls, such wood surfaces shall be separated from any plaster finish with No. 15 asphalt felt, Grade 'D' paper or other approved material per Section 1404.2 of this code, unless the wood is preservative-treated or naturally durable.
Exception: Clay plasters, see Section AR106.9.7
Section AR107 FIRE-RESISTANCE
AR107.1 Fire-Resistance Rating.
AR107.2 Rating with Plaster Finish. Plastered straw bale walls have a one-hour fire resistance rating, provided the components of the wall fit with all of the following parameters:
AR107.2.1 Bales may be laid flat or on-edge.
AR107.2.2 The bale wall must have a minimum un-plastered thickness of fourteen (14") inches.
AR107.2.3 Bales may be installed in a running bond or stack bond, but vertical joints in a stack bond and continuous vertical gaps at any posts within both types of wall, must be fire-stopped with straw-clay.
AR107.2.4. The wall must be finished on both sides and exposed ends with a plaster of any type allowed by this appendix. Clay plaster must be a minimum 1-1/2" thick and a minimum of two layers.
AR107.2.5 The wall may be no closer than five (5') to a property line.
AR107.2.6 Rating with other finishes. Straw bale walls covered with finish materials other than or in addition to plaster, shall be deemed to have the equivalent fire resistive rating as wood-frame construction covered with the same finish materials.
AR107.3 Permitted in Types of Construction. Straw bale walls with a one-hour fire resistance rating per Section AR107.2 are permitted wherever combustible one-hour walls are allowed by Chapter 6 of the IBC. Such walls and unrated straw bale walls with any finish allowed by this code are permitted whenever combustible no-hour walls are allowed in Chapter 6 of the IBC.
AR107.4 Openings in Rated Walls. Openings and penetrations in any straw bale wall rated and required to be rated for a particular fire-resistance rating and for a particular applications, shall satisfy the same requirements for openings and penetrations in walls with the same fire-resistive rating and application as stated elsewhere in this code.
AR107.5 Clearance to Fireplaces and Chimneys. Straw bale surfaces adjacent to fireplaces or chimneys shall have a minimum of 2" clearance from the surfaces of the plaster coat and the chimney structure. The space between can be bridged by non-combustible materials, such as flashing and aluminum or other metal channel materials.
Section AR108 ELECTRICAL
AR108.1 Scope. Wiring and other elements of the electrical system within or mounted to straw bale walls shall comply with all Sections of this code which govern electrical systems and with the 2011 National Electric Code.
AR108.2 Wiring. Type NM or UF cable may be used, or wiring may be in metallic or non-metallic conduit (which is the preferred method). Wiring which is unprotected by conduit shall be installed a minimum of two (2") inches from the face of the bale, except as necessary to enter or exit a junction box. The wiring shall be pushed into joints between bales or into the bale itself or the bales may be channeled to receive the wire.
AR108.3 Wiring Attachment. Where not held securely between bales or within a bale and not attached via staples to a wood member, wiring on straw bale walls shall be attached with minimum 17 gauge wire in a "U" configuration with a minimum eight (8") long legs.
AR108.4 Attachment of Electrical Boxes. Electrical boxes on bale walls shall be securely fastened to non-bale structural elements or to wooden stakes driven a minimum of twelve (12") into the bales or shall be secured by a combination of wire mesh and plaster, or by an acceptable equivalent method.
AR108.5 Attachment of Service and Sub-panels. Electrical service and sub-panels on bale walls shall be securely fastened to wood structural members, or to other wood members that have been adequately fastened to the straw bales. All proposed service panel and sub-panel support members shall be approved by the field inspector prior to attachment. The administrative authority, Arizona Public Service, retains the right to make any adjustments for support requirements and should be contacted prior to installation.
Section AR109 WALL AND ROOF BEARING ASSEMBLY ANCHORAGE AND CONSTRUCTION
AR109.1 General. The following is a recommended construction technique for straw bale construction. A designer or Arizona Registered design professional may submit other proposed methods as long as the general requirements of this Section and the International Building Codes are followed.
AR109.2 Bale interconnection support. Vertical reinforcing bars with a minimum diameter of 1/2" (#4 rebar), shall be embedded in the foundation at a minimum depth of six (6") inches and shall extend above the foundation a minimum of twelve (12") for the purpose of impaling the first course of bales. These vertical bars shall be located along the centerline of the bale wall, spaced not more than two (2) feet apart. A vertical bar shall also be located within one (1) foot of any opening (doors or window element) or corner, except at locations occupied by anchor bolts. These pins or bars will be wet set along with the anchor bolts.
AR109.3 Intersecting walls. Wall of other materials intersecting the straw bale walls shall be attached to the bale wall by means of one or more of the following methods or an acceptable equivalent.
(Ord. 2008-12, Amended, 04/15/2008; Ord. 2009-06, Amended, 07/18/2009; Ord. 2011-12, Amended, 07/19/2011; Ord. 2013-12, Amended, 07/02/2013)