BILL NUMBER: AB 1314 CHAPTERED
BILL TEXT
CHAPTER 941
FILED WITH SECRETARY OF STATE OCTOBER 16, 1995
APPROVED BY GOVERNOR OCTOBER 15, 1995
PASSED THE ASSEMBLY SEPTEMBER 12, 1995
PASSED THE SENATE SEPTEMBER 6, 1995
AMENDED IN SENATE SEPTEMBER 1, 1995
AMENDED IN SENATE JUNE 28, 1995
AMENDED IN SENATE JUNE 22, 1995
AMENDED IN SENATE JUNE 15, 1995
AMENDED IN ASSEMBLY MAY 10, 1995
AMENDED IN ASSEMBLY APRIL 18, 1995
AMENDED IN ASSEMBLY MARCH 30, 1995
INTRODUCED BY Assembly Members Sher, Richter, and Woods
(Coauthor: Senator Johannessen)
FEBRUARY 23, 1995
An act to add Chapter 4.5 (commencing with Section 18944.30) to
Part 2.5 of Division 13 of the Health and Safety Code, relating to
buildings.
LEGISLATIVE COUNSEL'S DIGEST
AB 1314, Sher. Buildings: straw-bale structures.
Existing law, known as the State Building Standards Law, creates
the California Building Standards Commission and authorizes it to
review proposed building standards, adopt or reject these proposed
standards, and codify and publish the adopted standards in the
California Building Standards Code. Local agencies have the
responsibility for the enforcement of numerous provisions of the
California Building Standards Code.
This bill would amend the State Building Standards Law to
establish safety guidelines for the construction of structures,
including single-family dwellings, that use baled rice straw, as
defined, as a loadbearing or nonloadbearing material.
This bill would provide that the guidelines proposed by this bill
shall not become operative within any city or county unless and until
an express finding is made, as specified, and the finding is filed
with the Department of Housing and Community Development.
This bill would, subject to the availability of funds, require the
California Building Standards Commission, on or before January 1,
2002, to transmit, to the Department of Housing and Community
Development and to the Legislature, a report regarding the
implementation of the bill.
This bill would specify that none of its provisions be construed
as an exemption from either the Architects Practice Act or the
Professional Engineers Act, relative to the preparation of plans,
drawings, specifications, or calculations under the direct
supervision of a licensed architect or registered engineer, for
construction of structures that deviate from the conventional framing
requirements for wood-frame construction.
THE PEOPLE OF THE STATE OF CALIFORNIA DO ENACT AS FOLLOWS:
SECTION 1. Chapter 4.5 (commencing with Section 18944.30) is added
to Part 2.5 of Division 13 of the Health and Safety Code, to read:
CHAPTER 4.5. GUIDELINES FOR STRAW-BALE STRUCTURES
Article 1. General Provisions and Definitions
18944.30. (a) The Legislature finds and declares all of the
following:
(1) There is an urgent need for low-cost, energy-efficient housing
in California.
(2) The cost of conventional lumber-framed housing has risen due
to a shortage of construction-grade lumber.
(3) Rice straw is an annually renewable source of cellulose that
can be used as an energy-efficient substitute for stud-framed wall
construction.
(4) The state has mandated that the burning of rice straw be
prohibited as specified in statute by the year 2000 in an annual
phased reduction.
(5) As a result of the mandated burning reduction, growers are
experimenting with alternative straw management practices. Various
methods of straw incorporation into the soil are the most widely used
alternatives. The two most common methods are nonflood
incorporation and winter flood incorporation. Economically viable
off-farm uses for rice straw are not yet available.
(6) Winter flooding of rice fields encourages the natural
decomposition of rice straw and provides valuable waterfowl habitat.
According to the Central Valley Habitat Joint Venture component of
the North American Waterfowl Management Plan, in California's Central
Valley, over 400,000 acres of enhanced agricultural lands are needed
to restore the depleted migratory waterfowl populations of the
Pacific flyway. Flooded rice fields are a key and integral part of
the successful restoration of historic waterfowl and shorebird
populations.
(7) Winter flooding of rice fields provides significant waterfowl
habitat benefits and should be especially encouraged in areas where
there is minimal potential to impact salmon as a result of surface
water diversions.
(8) An economically viable market for rice straw bales could
result from the use of rice straw bales in housing construction.
(9) Existing regulatory requirements are costly and severely
restrict the development of straw-bale housing.
(10) Statutory guidelines for the use of straw-bale housing would
significantly benefit low-cost housing, agriculture, and fisheries in
California.
(b) It is therefore the intent of the Legislature to adopt safety
guidelines for the construction of structures including, but not
limited to, single-family dwellings that use baled rice straw as a
loadbearing or nonloadbearing material, provided that these
guidelines shall not be effective within any city or county unless
and until the legislative body of the city or county makes an express
finding that the application of these guidelines within the city or
county is reasonably necessary because of local conditions.
18944.31. (a) Notwithstanding any other provision of law, the
guidelines established by this chapter shall not become operative
within any city or county unless and until the legislative body of
the city or county makes an express finding that the application of
these guidelines within the city or county is reasonably necessary
because of local conditions and the city or county files a copy of
that finding with the department.
(b) In adopting ordinances or regulations, a city or county may
make any changes or modifications in the guidelines contained in this
chapter as it determines are reasonably necessary because of local
conditions, provided the city or county files a copy of the changes
or modifications and the express findings for the changes or
modifications with the department. No change or modification of that
type shall become effective or operative for any purpose until the
finding and the change or modification has been filed with the
department.
18944.32. Nothing in this chapter shall be construed as an
exemption from Chapter 3 (commencing with Section 5500) of, or
Chapter 7 (commencing with Section 6700) of, Division 3 of the
Business and Professions Code relative to preparation of plans,
drawings, specifications, or calculations under the direct
supervision of a licensed architect or civil engineer, for the
construction of structures that deviate from the conventional framing
requirements for wood-frame construction.
18944.33. For the purposes of this chapter, the following terms
are defined as follows:
(a) "Bales" means rectangular compressed blocks of rice straw,
bound by strings or wire.
(b) "Department" means the Department of Housing and Community
Development.
(c) "Flakes" means slabs of straw removed from an untied bale.
Flakes are used to fill small gaps between the ends of stacked bales.
(d) "Laid flat" refers to stacking bales so that the sides with
the largest cross-sectional area are horizontal and the longest
dimension of this area is parallel with the wall plane.
(e) "Laid on-edge" refers to stacking bales so that the sides with
the largest cross-sectional area are vertical and the longest
dimension of this area is horizontal and parallel with the wall
plane.
(f) "Straw" means the dry stems of cereal grains left after the
seed heads have been removed.
18944.34. (a) Subject to the availability of funds, on or before
January 1, 2002, the California Building Standards Commission shall
transmit, to the department and to the Legislature, a report
regarding the implementation of this chapter.
(b) The implementation report shall describe which cities and
counties have utilized this chapter, and the number and type of
structures that have been built pursuant to local ordinances. The
implementation report may include recommendations to amend the
guidelines established by this chapter, or any other related matters.
(c) The California Building Standards Commission may accept and
use any funds provided or donated for the purposes of this section.
Article 2. Guidelines for Materials
18944.35. (a) Bales shall be rectangular in shape.
(b) Bales used within a continuous wall shall be of consistent
height and width to ensure even distribution of loads within wall
systems.
(c) Bales shall be bound with ties of either polypropylene string
or baling wire. Bales with broken or loose ties shall not be used
unless the broken or loose ties are replaced with ties which restore
the original degree of compaction of the bale.
(d) The moisture content of bales, at the time of installation,
shall not exceed 20 percent of the total weight of the bale.
Moisture content of bales shall be determined through the use of a
suitable moisture meter, designed for use with baled rice straw or
hay, equipped with a probe of sufficient length to reach the center
of the bale, and used to determine the average moisture content of
five bales randomly selected from the bales to be used.
(e) Bales in loadbearing walls shall have a minimum calculated dry
density of 7.0 pounds per cubic foot. The calculated dry density
shall be determined after reducing the actual bale weight by the
weight of the moisture content.
(f) Where custom-made partial bales are used, they shall be of the
same density, same string or wire tension, and, where possible, use
the same number of ties as the standard size bales.
(g) Bales of various types of straw, including wheat, rice, rye,
barley, oats, and similar plants, as determined by the building
official, shall be acceptable if they meet the minimum requirements
of this chapter for density, shape, moisture content, and ties.
Article 3. Construction Guidelines
18944.40. (a) Straw-bale walls, when covered with plaster,
drywall, or stucco, shall be deemed to have the equivalent fire
resistive rating as wood-frame construction with the same
wall-finishing system.
(b) Minimum bale wall thickness shall be 13 inches.
(c) Buildings with loadbearing bale walls shall not exceed one
story in height, and the bale portion of the loadbearing walls shall
not exceed a height-to-width ratio of 5.6:1 (for example, the maximum
height for a wall that is 23 inches thick would be 10 feet 8
inches).
(d) The ratio of unsupported wall length to thickness, for
loadbearing walls, shall not exceed 15.7:1 (for example, for a wall
that is 23 inches thick, the maximum unsupported length allowed is 30
feet).
(e) The allowable vertical load (live and dead load) on top of
loadbearing bale walls shall not exceed 400 pounds per square foot,
and the resultant load shall act at the center of the wall.
Straw-bale structures shall be designed to withstand all vertical and
horizontal loads as specified in the latest edition of the Uniform
Building Code.
(f) Foundations shall be sized to accommodate the thickness of the
bale wall and the load created by the wall and roof live and dead
loads. Foundation or stem walls which support bale walls shall
extend to an elevation of not less than 6 inches above adjacent
ground at all points. The minimum width of the footing shall be the
width of the bale it supports, except that the bales may overhang the
exterior edge of the foundation by not more than 3 inches to
accommodate rigid perimeter insulation. Footings shall extend a
minimum of 12 inches below natural, undisturbed soil, or to the frost
line, whichever is lower.
(g) (1) Vertical reinforcing bars with a minimum diameter of 1/2
inch shall be embedded in the foundation to a minimum depth of 7
inches, and shall extend above the foundation by a minimum of 12
inches. These vertical bars shall be located along the center line
of the bale wall, spaced not more than 2 feet apart. A vertical bar
shall also be located within 1 foot of any opening or corner, except
at locations occupied by anchor bolts.
(2) Nonbale walls abutting bale walls shall be attached by means
of one or more of the following methods or by means of an acceptable
equivalent:
(A) Wooden dowels of 5/8 inch minimum diameter and of sufficient
length to provide 12 inches of penetration into the bale, driven
through holes bored in the abutting wall stud, and spaced to provide
one dowel connection per bale.
(B) Pointed wooden stakes, a minimum of 12 inches in length and
11/2 inches by 31/2 inches at the exposed end, fully driven into each
course of bales, as anchorage points.
(C) Bolted or threaded rod connection of the abutting wall,
through the bale wall, to a steel nut and steel or plywood plate
washer, a minimum of 6 inches square and a minimum thickness of 3/16
of an inch for steel and 1/2 inch for plywood, in a minimum of three
locations.
(3) (A) Loadbearing bale walls shall be anchored to the foundation
at intervals of 6 feet or less. There shall be embedded in the
foundation a minimum of 21/2 inch diameter steel anchor bolts per
wall, with one bolt located within 36 inches of each end of each
wall. Sections of 1/2 inch diameter threaded rod shall be connected
to the anchor bolts, and to each other, by means of threaded coupling
nuts, and shall extend through the roof bearing assembly and be
fastened with a steel washer and nut.
(B) Bale walls and roof bearing assemblies may be anchored to the
foundation by means of other methods which are adequate to resist
uplift forces resulting from the design wind load. There shall be a
minimum of two points of anchorage per wall, spaced not more than 6
feet apart, with one located within 36 inches of each end of each
wall.
(C) With loadbearing bale walls, the dead load of the roof and
ceiling systems will produce vertical compression of the walls.
Regardless of the anchoring system used to attach the roof bearing
assembly to the foundation, prior to installation of wall finish
materials, the nuts, straps, or cables shall be retightened to
compensate for this compression.
(h) (1) A moisture barrier shall be used between the top of the
foundation and the bottom of the bale wall to prevent moisture from
migrating through the foundation so as to come into contact with the
bottom course of bales. This barrier shall consist of one of the
following:
(A) Cementitious waterproof coating.
(B) Type 30 asphalt felt over an asphalt emulsion.
(C) Sheet metal flashing, sealed at joints.
(D) Another building moisture barrier, as approved by the building
official.
(2) All penetrations through the moisture barrier, as well as all
joints in the barrier, shall be sealed with asphalt, caulking, or an
approved sealant.
(i) (1) For nonloadbearing walls, bales may be laid either flat or
on-edge. Bales in loadbearing bale walls shall be laid flat and be
stacked in a running bond, where possible, with each bale overlapping
the two bales beneath it. Overlaps shall be a minimum of 12 inches.
Gaps between the ends of bales which are less than 6 inches in
width may be filled by an untied flake inserted snugly into the gap.
(2) The first course of bales shall be laid by impaling the bales
on the rebar verticals and threaded rods, if any, extending from the
foundation. When the fourth course has been laid, vertical #4 rebar
pins, or an acceptable equivalent, long enough to extend through all
four courses, shall be driven down through the bales, two in each
bale, located so that they do not pass through the space between the
ends of any two bales. The layout of these rebar pins shall
approximate the layout of the rebar pins extending from the
foundation. As each subsequent course is laid, two pins, long enough
to extend through that course and the three courses immediately
below it, shall be driven down through each bale. This pinning
method shall be continued to the top of the wall. In walls seven or
eight courses high, pinning at the fifth course may be eliminated.
(3) Alternative pinning method: when the third course has been
laid, vertical #4 rebar pins, or an acceptable equivalent, long
enough to extend through all three courses, shall be driven down
through the bales, two in each bale, located so that they do not pass
through the space between the ends of any two bales. The layout of
these rebar pins shall approximate the layout of the rebar pins
extending from the foundation. As each subsequent course is laid,
two pins, long enough to extend through that course and the two
courses immediately below it, shall be driven down through each bale.
This pinning method shall be continued to the top of the wall.
(4) Only full-length bales shall be used at corners of loadbearing
bale-walls.
(5) Vertical #4 rebar pins, or an acceptable alternative, shall be
located within one foot of all corners or door openings.
(6) Staples, made of #3 or larger rebar formed into a "U" shape, a
minimum of 18 inches long with two 6-inch legs, shall be used at all
corners of every course, driven with one leg into the top of each
abutting corner bale.
(j) (1) All loadbearing bale walls shall have a roof bearing
assembly at the top of the walls to bear the roof load and to provide
the means of connecting the roof structure to the foundation. The
roof bearing assembly shall be continuous along the tops of
loadbearing bale walls.
(2) An acceptable roof bearing assembly option consists of two
double 2-inch by 6-inch, or larger, horizontal top plates, one
located at the inner edge of the wall and the other at the outer
edge. Connecting the two doubled top plates, and located
horizontally and perpendicular to the length of the wall, shall be
2-inch by 6-inch cross members, spaced no more than 72 inches center
to center, and as required to align with the threaded rods extending
from the anchor bolts in the foundation. The double 2-inch by 6-inch
top plates shall be face-nailed with 16d nails staggered at 16-inch
o.c., with laps and intersections face-nailed with four 16d nails.
The cross members shall be face-nailed to the top plates with four
16d nails at each end. Corner connections shall include overlaps
nailed as above or an acceptable equivalent, such as plywood gussets
or metal plates. Alternatives to this roof bearing assembly option
shall provide equal or greater vertical rigidity and provide
horizontal rigidity equivalent to a continuous double 2 by 4 top
plate.
(3) The connection of roof framing members to the roof plate shall
comply with the appropriate sections of the California Building
Code.
(k) All openings in loadbearing bale walls shall be a minimum of
one full bale length from any outside corner, unless exceptions are
approved by an engineer or architect licensed by the state to
practice. Wall or roof load present above any opening shall be
carried, or transferred, to the bales below by one of the following:
(1) A frame, such as a structural window or door frame.
(2) A lintel, such as an angle-iron cradle, wooden beam, or wooden
box beam. Lintels shall be at least twice as long as the opening is
wide and extend a minimum of 24 inches beyond either side of the
opening. Lintels shall be centered over openings.
(3) A roof bearing assembly designed to act as a rigid beam over
the opening.
(l) (1) All weather-exposed bale walls shall be protected from
water damage. However, nonbreathing moisture barriers shall not be
used on the upper two-thirds of vertical exterior surfaces of bale
walls in order to allow natural transpiration of moisture from the
bales.
(2) Bale walls shall have special moisture protection provided at
all window sills. Unless protected by a roof, the tops of walls
shall also be protected. This moisture protection shall consist of a
waterproof membrane, such as asphalt-impregnated felt paper,
polyethylene sheeting, or other moisture barrier, as approved by the
building official, installed in a manner that will prevent water from
entering the wall system at windowsills or at the tops of walls.
(m) (1) Interior and exterior surfaces of bale walls shall be
protected from mechanical damage, flame, animals, and prolonged
exposure to water. Bale walls adjacent to bath and shower enclosures
shall be protected by a moisture barrier.
(2) Cement stucco shall be reinforced with galvanized woven wire
stucco netting or an equivalent, as approved by the building
official. The reinforcement shall be secured by attachment through
the wall at a maximum spacing of 24 inches horizontally and 16 inches
vertically.
(3) Where bales abut other materials, the plaster or stucco shall
be reinforced with galvanized expanded metal lath, or an acceptable
equivalent, extending a minimum of 6 inches onto the bales.
(4) Earthen and lime-based plasters may be applied directly onto
bale walls without reinforcement, except where applied over materials
other than straw.
(n) (1) All wiring within or on bale walls shall meet all
provisions of the California Electrical Code. Type "NM" or "UF"
cable may be used, or wiring may be run in metallic or nonmetallic
conduit systems.
(2) Electrical boxes shall be securely attached to wooden stakes
driven a minimum of 12 inches into the bales, or an acceptable
equivalent.
(o) Water or gas pipes within bale walls shall be encased in a
continuous pipe sleeve to prevent leakage within the wall. Where
pipes are mounted on bale walls, they shall be isolated from the
bales by a moisture barrier.