Appendix AQ — TINY HOUSES

(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user.

See Chapter 1 for state agency authority and building applications.)

APPENDIX AQ

TINY HOUSES

This provisions contained in this appendix are not mandatory unless specifically adopted by a state agency or referenced in the adopting ordinance.

User note:

About this appendix: Appendix AQ relaxes various requirements in the body of the code as they apply to houses that are 400 square feet in area or less. Attention is specifically paid to features such as compact stairs, including stair handrails and headroom, ladders, reduced ceiling heights in lofts and guard and emergency escape and rescue opening requirements at lofts.

walls. Light-frame walls perpendicular to, or at an angle to a strawbale wall assembly, shall be fastened to the bottom and top wood members of the strawbale wall in accordance with requirements for wood or cold-formed steel light-frame walls in this code, or the abutting stud shall be connected to alternating strawbale courses with a ¹ /2-inch diameter (12.7 mm) steel, ³ /4-inch-diameter (19.1 mm) wood or ⁵ /8-inch-diameter (15.9 mm) bamboo dowel, with not less than 8-inch (203 mm) penetration.

Strawbale walls shall be protected from moisture intrusion and damage in accordance with Sections AS105.6.1 through AS105.6.9.

AS105.6.1 Water-resistant barriers and vapor perme- ance ratings. Plastered bale walls shall be constructed without any membrane barrier between straw and plaster to facilitate transpiration of moisture from the bales, and to secure a structural bond between straw and plaster, except as permitted or required elsewhere in this appendix. Where a water-resistant barrier is placed behind an exterior finish, it shall have a vapor permeance rating of not less than 5 perms, except as permitted or required elsewhere in this appendix.

AS105.6.2 Vapor retarders. Wall finishes shall have an equivalent vapor permeance rating of a Class III vapor retarder on the interior side of exterior strawbale walls in Climate Zones 5, 6, 7, 8 and Marine 4, as defined in Chapter 11. Bales in walls enclosing showers or steam rooms shall be protected on the interior side by a Class I or Class II vapor retarder.

AS105.6.3 Penetrations in exterior strawbale walls. Penetrations in exterior strawbale walls shall be sealed with an approved sealant or gasket on the exterior side of the wall in all climate zones, and on the interior side of the wall in Climate Zones 5, 6, 7, 8 and Marine 4, as defined in Chapter 11 .

AS105.6.4 Horizontal surfaces. Bale walls and other bale elements shall be provided with a water-resistant barrier at weather-exposed horizontal surfaces. The water-resistant barrier shall be of a material and installation that will prevent water from entering the wall system. Horizontal surfaces shall include exterior window sills, sills at exterior niches and buttresses. Horizontal surfaces shall be sloped not less than 1 unit vertical in 12 units horizontal (8-percent slope) and shall drain away from bale walls and elements. Where the water-resistant barrier is below the finish material, it shall be sloped not less than 1 unit vertical in 12 units horizontal (8-percent slope) and shall drain to the outside surface of the bale wall’s vertical finish.

AS105.6.5 Separation of bales and concrete. A sheet or liquid-applied Class II vapor retarder shall be installed

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APPENDIX AS—STRAWBALE CONSTRUCTION

strawbale structural walls. Buildings using strawbale structural walls shall be subject to the following limitations and requirements:

1. Number of stories: Not more than one, except that two stories shall be allowed with an approved engineered design.

2. Building height: Not more than 25 feet (7620 mm), except that greater heights shall be allowed with an approved engineered design.

3. Wall height: In accordance with Table AS105.4, AS106.13(2) or AS106.13(3) as applicable, whichever is most restrictive.

4. Braced wall panel lengths: The greater of the values determined in accordance with Tables AS106.13(2) and AS106.13(3) for buildings using strawbale braced wall panels, or in accordance with Item 4 of Section AS105.2 for buildings with load-bearing strawbale walls that do not use strawbale braced wall panels.

Live and dead loads and other limitations shall be in accordance with Section R301. Strawbale wall dead loads shall not exceed 60 psf (2872 N/m ² ) per face area of wall.

Foundations for plastered strawbale walls shall be in accordance with Chapter 4, Figure AS105.1(1), Figure AS105.1(2) or an approved engineered design.

Bales in strawbale structural walls shall be laid flat or on-edge and in a running bond or stack bond, except that bales in structural walls with unreinforced plasters shall be laid in a running bond only.

Plaster on load-bearing walls shall be in accordance with Table AS106.12. Plaster on shear walls shall be in accordance with Table AS106.13(1).

AS106.6.1 Compressive strength. For plaster on strawbale structural walls, the building official is authorized to require a 2-inch (51mm) cube test conforming to ASTM C109 to demonstrate a minimum compressive strength in accordance with Table AS106.6.1.

TABLE AS106.6.1 MINIMUM COMPRESSIVE STRENGTH FOR PLASTERS ON STRUCTURAL WALLS

For SI: 1 pound per square inch = 6894.76 N/m ² .

Plaster on strawbale structural walls shall be straight, as a function of the bale wall surfaces they are applied to, in accordance with all of the following:

1. As measured across the face of a bale, straw bulges shall not protrude more than ³ /4 inch (19.1 mm) across 2 feet (610 mm) of its height or length.

2. As measured across the face of a bale wall, straw bulges shall not protrude from the vertical plane of a bale wall more than 2 inches (51 mm) over 8 feet (2438 mm).

3. The vertical faces of adjacent bales shall not be offset more than ³ /8 inch (9.5 mm).

Strawbale structural walls shall not have a membrane between straw and plaster, or shall have attachment through the bale wall from one plaster skin to the other in accordance with an approved engineered design.

Mesh in plasters on strawbale structural walls, and where required by Table AS105.4, and where used to resist wind uplift in accordance with Section AS106.14, shall be installed in accordance with Sections AS106.9.1 through AS106.9.4.

AS106.9.1 Mesh laps. Mesh required by Table AS105.4 or AS106.12 shall be installed with not less than 4-inch (102 mm) laps. Mesh required by Table AS106.13(1) or in walls designed to resist wind uplift of more than 100 plf (1459 N/m) in accordance with Section AS106.14, shall run continuous vertically from sill plate to the top plate or roof-bearing element, or shall lap not less than 8 inches (203 mm). Horizontal laps in such mesh shall be not less than 4 inches (102 mm).

AS106.9.2 Mesh attachment. Mesh shall be attached with staples to top plates or roof-bearing elements and to sill plates in accordance with all of the following:

1. Staples. Staples shall be pneumatically driven, stainless steel or electro-galvanized, 16 gage with 1 ¹ /2-inch (38 mm) legs, ⁷ /16-inch (11.1 mm) crown; or manually driven, galvanized, 15 gage with 1-inch (25 mm) legs. Other staples shall be as designed by a registered design professional. Staples into preservative-treated wood shall be stainless steel.

2. Staple orientation. Staples shall be firmly driven diagonally across mesh intersections at the required spacing.

3. Staple spacing. Staples shall be spaced not more than 4 inches (102 mm) on center, except where a lesser spacing is required by Table AS106.13(1) or Section AS106.14, as applicable.

AS106.9.3 Steel mesh. Steel mesh shall be galvanized, and shall be separated from preservative-treated wood by Grade D paper, No. 15 roofing felt or other approved barrier.

AS106.9.4 Mesh in plaster. Required mesh shall be embedded in the plaster except where staples fasten the mesh to horizontal boundary elements.

APPENDIX AS-12 2022 CALIFORNIA RESIDENTIAL CODE

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

Plaster skins on strawbale structural walls shall be continuously supported along their bottom edge. Acceptable supports include: a concrete or masonry stem wall, a concrete slab-on-grade, a wood-framed floor in accordance with Figure AS105.1(2) and an approved engineered design or a steel angle anchored with an approved engineered design. A weep screed as described in Section R703.7.2.1 is not an acceptable support.

Where plastered strawbale walls are used to support superimposed vertical loads, such loads shall be transferred to the plaster skins by continuous direct bearing in accordance with Figure AS105.1(3) or by an approved engineered design. Where plastered strawbale walls are used to resist in-plane lateral loads, such loads shall be transferred to the reinforcing mesh from the structural member or assembly above in accordance with Figure AS105.1(3) or AS105.1(4) and to the sill plate in accordance with Figure AS105.1(1) or AS105.1(2) and with Table AS106.13(1).

Bearing capacities for plastered strawbale walls used as load-bearing walls in one-story buildings to support vertical loads imposed in accordance with Section R301 shall be in accordance with Table AS106.12.

AS106.12.1 Precompression of load-bearing strawbale walls. Prior to application of plaster, walls designed to be load-bearing shall be precompressed by a uniform load of not less than 100 plf (1459 N/m).

AS106.12.2 Concentrated loads. Concentrated loads shall be distributed by structural elements capable of distributing the loads to the bearing wall within the allowable bearing capacity listed in Table AS106.12 for the plaster type used.

AS106.12.3 Roof-bearing assembly. Roof-bearing assemblies shall be of nominal 2-inch by 6-inch (51 mm by 152 mm) lumber with ¹⁵ /32-inch (12 mm) plywood or OSB panels fastened with 8d nails at 6 inches (152 mm) on center in accordance with Figure AS105.1(3) and Items 1 through 6, or be of an approved engineered design.

1. Assembly shall be a box assembly on the top course of bales, with the panels horizontal.

APPENDIX AS—STRAWBALE CONSTRUCTION

2. Assembly shall be the width of the strawbale wall and shall comply with Section AS106.11.

3. Discontinuous lumber shall be spliced with a metal strap with not less than a 500-pound (2224 N) allowable wind or seismic load tension capacity. Where the wall line includes a braced wall panel the strap shall have not less than a 2,000-pound (8896 N) capacity.

4. Panel joints shall be blocked.

5. Roof and ceiling framing shall be attached to the roof-bearing assembly in accordance with Table R602.3(1), Items 2 and 6.

6. Where the roof-bearing assembly spans wall openings, it shall comply with Section AS106.12.3.1

AS106.12.3.1 Roof-bearing assembly spanning openings. Roof-bearing assemblies that span openings in strawbale walls shall comply with the following at each opening:

1. Lumber on each side of the assembly shall be of the dimensions and quantity required to span each opening in accordance with Table R602.7(1).

2. The required lumber in the assembly shall be supported at each side of the opening by the number of jack studs required by Table R602.7(1), or shall extend beyond the opening on both sides a distance, D, using the following equation:

D = S × R /2 / (1- R ) (Equation AS-1)

where: D = Minimum distance (in feet) for required spanning

lumber to extend beyond the opening S = Span in feet R = BL / BC BL = Design load on the wall (in pounds per lineal foot) in

accordance with Sections R301.4 and R301.6 BC = Allowable bearing capacity of the wall in accordance

with Table AS106.12

TABLE AS106.12 LLOWABLE SUPERIMPOSED VERTICAL LOADS (LBS/FOOT) FOR PLASTERED LOAD-BEARING STRAWBALE WALLS

For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.5939 N/m. a. Plasters shall conform to Sections AS104.4.3 through AS104.4.9, AS106.7 and AS106.10. b. Any metal mesh allowed by this appendix and installed in accordance with Section AS106.9. c. In accordance with Section AS106.9.2, except as required to transfer roof loads to the plaster skins in accordance with Section AS106.11. d. For walls with a different plaster on each side, the lower value shall be used. For walls with plaster on only one side, half of the tabular value shall be used. e. Shall use hydraulic or natural hydraulic lime.

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AS—STRAWBALE CONSTRUCTION

Plastered strawbale walls used as braced wall panels for one-story buildings shall be in accordance with Section R602.10 and Tables AS106.13(1), AS106.13(2) and AS106.13(3). Wind design criteria shall be in accordance with Section R301.2.1. Seismic design criteria shall be in accordance with Section R301.2.2. An approved engineered design in accordance with Section R301.2.1 shall be required where the building is located in a special wind region or where wind design is required in accordance with Figure R301.2(2) and Section R301.2.1.1, respectively.

AS106.13.1 Bale wall thickness. The thickness of strawbale braced wall panels without their plaster shall be not less than 15 inches (381 mm).

AS106.13.2 Sill plates. Sill plates shall be in accordance with Table AS106.13(1).

AS106.13.3 Sill plate fasteners. Sill plates shall be fastened with not less than ⁵ /8-inch-diameter (15.9 mm) steel anchor bolts with 3-inch by 3-inch by ³ /16-inch (76.2 mm by 76.2 mm by 4.8 mm) steel washers, with not less than 7-inch (177.8 mm) embedment in a concrete or masonry foundation, or shall be an approved equivalent, with the spacing shown in Table AS106.13(1). Anchor

bolts or other fasteners into framed floors shall be of an approved engineered design.

Plaster mesh in skins of strawbale walls that resist uplift forces from the roof assembly, as determined in accordance with Section R802.11, shall be in accordance with all of the following:

1. Plaster shall be any type and thickness allowed in Section AS104.

2. Mesh shall be any type allowed in Table AS106.13(1), and shall be attached to top plates or roof-bearing elements and to sill plates in accordance with Section AS106.9.2.

3. Sill plates shall be not less than nominal 2-inch by 4inch (51 mm by 102 mm) with anchoring complying with Section R403.1.6.

4. Mesh attached with staples at 4 inches (51 mm) on center shall be considered to be capable of resisting uplift forces of 100 plf (1459 N/m) for each plaster skin.

5. Mesh attached with staples at 2 inches (51 mm) on center shall be considered to be capable of resisting uplift forces of 200 plf (2918 N/m) for each plaster skin.

TABLE AS106.13(1) PLASTERED STRAWBALE BRACED WALL PANEL TYPES

For SI: 1 inch = 25.4 mm. a. Plasters shall comply with Sections AS104.4.3 through AS104.4.9, AS106.7, AS106.8 and AS106.12. b. Sill plates shall be Douglas fir-larch or southern pine and shall be preservative treated where required by the California Residential Code . c. Anchor bolts shall be in accordance with Section AS106.13.3 at the spacing shown in this table. d. Installed in accordance with Section AS106.9. e. Staples shall be in accordance with Section AS106.9.2 at the spacing shown in this table. f. Shall use hydraulic or natural hydraulic lime.

APPENDIX AS-14 2022 CALIFORNIA RESIDENTIAL CODE

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AS—STRAWBALE CONSTRUCTION

TABLE AS106.13(2) BRACING REQUIREMENTS FOR STRAWBALE BRACED WALL PANELS BASED ON WIND SPEED

For SI: 1 foot = 305 mm, 1 mile per hour = 0.447 m/s. a. Linear interpolation shall be permitted. b. All braced wall panels shall be without openings and shall have an aspect ratio (H:L) ≤ 2:1. c. Tabulated minimum total lengths are for braced wall lines using single-braced wall panels with an aspect ratio (H:L) ≤ 2:1, or using multiple braced wall

panels with aspect ratios (H:L) ≤ 1:1. For braced wall lines using two or more braced wall panels with an aspect ratio (H:L) > 1:1, the minimum total length shall be multiplied by the largest aspect ratio (H:L) of braced wall panels in that line. d. Subject to applicable wind adjustment factors associated with “All methods” in Table AS106.13(2) e. Strawbale braced panel types indicated shall comply with Sections AS106.13.1 through AS106.13.3 and with Table AS106.13(1).

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AS—STRAWBALE CONSTRUCTION

TABLE AS106.13(3) BRACING REQUIREMENTS FOR STRAWBALE BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY

For SI: 1 inch = 25.4 mm, 1 foot = 305 mm, 1 pound per square foot = 0.0479 kPa. a. Linear interpolation shall be permitted. b. Braced wall panels shall be without openings and shall have an aspect ratio (H:L) ≤ 2:1. c. Tabulated minimum total lengths are for braced wall lines using single braced wall panels with an aspect ratio (H:L) ≤ 2:1, or using multiple braced wall

panels with aspect ratios (H:L) ≤ 1:1. For braced wall lines using two or more braced wall panels with an aspect ratio (H:L) > 1:1, the minimum total length shall be multiplied by the largest aspect ratio (H:L) of braced wall panels in that line. d. Subject to applicable seismic adjustment factors associated with “All methods” in Table R602.10.3(4), except “Wall dead load.” e. Strawbale braced wall panel types indicated shall comply with Sections AS106.13.1 through AS106.13.3 and Table AS106.13(1). f. Wall bracing lengths are based on a soil site class “D.” Interpolation of bracing lengths between Sds values associated with the seismic design categories is

allowable where a site-specific Sds value is determined in accordance with Section 1613.3 of the California Building Code . g. Where using wall Type A3, the minimum total length of braced wall panels in this column shall be multiplied by 1.25.

Post-andbeam with strawbale infill systems shall be in accordance with Figure AS105.1(4) and Items 1 through 7, or be of an approved engineered design.

1. Beams shall be of the dimensions and number of members in accordance with Table R602.7(1), where the space between posts equals the span in the table.

2. Beam ends shall bear over posts not less than 1 ¹ /2 inches (38 mm) or be supported by a framing anchor in accordance with Table R602.7(1).

3. Discontinuous beam ends shall be spliced with a metal strap with not less than 1,000-pound (454 kg) wind or seismic load tension capacity. Where the wall line

includes a braced wall panel, the strap shall have not less than a 4,000-pound (1814 kg) capacity.

4. Each post shall equal NJ + 1 in accordance with Table R602.7(1), where the space between posts equals the span in the table.

5. Posts shall be connected to the beam by an approved means.

6. Roof and ceiling framing shall be attached to the beam in accordance with Table R602.3(1), Items 2 and 6.

7. Posts shall be supported by the sill plate of the bale wall in accordance with Section AS105.3 or AS106.13.2, with fastening in accordance with Table R602.3(1), Item 16, or shall be supported and fastened at their base by an approved means.

APPENDIX AS-16 2022 CALIFORNIA RESIDENTIAL CODE

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.