SECTION 07 21 00

THERMAL INSULATION - HEMPCRETE

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PART 1    GENERAL
1.1	SECTION INCLUDES
A.	Hempcrete thermal insulation
1.2	RELATED SECTIONS
A.	Section 03 52 16 - Lightweight Insulating Concrete.
B.	06 16 13 - Insulating Sheathing.
C.	Section 07 21 13 - Board Insulation.
D.	Section 07 21 16 - Blanket / Batt Insulation.
E.	Section 07 21 23 - Loose-Fill Insulation.
F.	Section 07 21 29 - Sprayed Insulation.
G.	Section 07 24 00 - Exterior Insulation and Finish Systems.
H.	Section 07 25 00 - Weather Barriers.
1.3	REFERENCES
A.	ASTM International (ASTM):
1.	ASTM C5 - Standard Specification for Quicklime for Structural Purposes. BL104.3.5.
2.	ASTM C141/C141M - Standard Specification for Hydrated Hydraulic Lime for Structural Purposes. BL104.3.5.
3.	ASTM C177 - Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus. BA106.2.
4.	ASTM C206 - Standard Specification for Finishing Hydrated Lime. BL104.3.5.
5.	ASTM C518 - Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus. BL106.2.
6.	ASTM C1114 - Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Thin-Heater Apparatus. BL106.2.
7.	ASTM C1363 - Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus. BL106.2.
8.	ASTM C1707 - Standard Specification for Pozzolanic Hydraulic Lime for Structural Purposes. BL104.3.5.
9.	ASTM E84-21a - Standard Test Method for Surface Burning Characteristics of Building Materials. BL106.4.
10.	ASTM E96 - Standard Test Methods for Water Vapor Transmission of Materials. BL104.1.
11.	ASTM E2392 / ASTM E2392M - Standard Guide for Design of Earth Wall Building Systems. BL104.3.6.1.
B.	European Committee for Standardization (CEN):
1.	CEN EN 459 - Part 1: Building Lime. Definitions, Specifications and Conformity Criteria; Part 2: Test Methods. BL104.3.5.
C.	International Residential Code (IRC):
1.	Appendix BL.
1.4	DEFINITIONS
A.	Binder: The material that binds the hemp hurd in a hempcrete mix.
B.	Bonding Coat: The initial thin layer of binder-rich granulated plaster used in lined applications of hempcrete construction to ensure adhesive and/or mechanical bonding. Also known as gobetis.
C.	Cast-In-Place: Installation of hempcrete mix by hand or by spraying into forms in its permanent location.
D.	Casting: Placing wet hempcrete into forms.
E.	Fiber Clumps: Long fibers that are attached to hemp hurd, or for other reasons, cause clumping of fibrous balls when agitated.
F.	Finish: Exposed surface material on the interior or exterior face of a hempcrete infill wall.
G.	Form: The material into which hempcrete infill, panels, or blocks are cast.
H.	Formwork: The system of forms, their bracing and fasteners assembled for casting of hempcrete infill.
I.	Hand Cast: Hempcrete infill cast by placing hempcrete mix into formwork and evenly tamping by hand or with a tool.
J.	Hemp: A class of the Cannabis sativa plant grown for industrial purposes in which the concentration of total delta-9 tetrahydrocannabinol (THC) in the flowering tops is equal to or less than the regulated maximum level established by authorities having jurisdiction.
K.	Hempcrete: Common usage term for non-structural hemp-lime.
L.	Hemp Hurd: The chopped woody core of the stalks of the hemp plant, stripped of its surrounding hemp fibers. Also known as hemp shiv or shive.
M.	Infill: Hempcrete placed between or around the structural or nonstructural framing of a building as insulation, thermal mass, and a substrate for finish.
N.	Lift: A horizontal layer of hempcrete infill.
O.	Lined Application: Installation of a vertical hempcrete layer, lining a masonry or concrete wall.
P.	Nonbearing: Not bearing the weight of the building other than the weight of the hempcrete infill and its finish.
Q.	Precast: Blocks or panels of hempcrete formed and cured before installation.
R.	Screeding: Removal of excess material to form a planar surface.
S.	Spray Applied: A method of pneumatic projection of hempcrete applied onto or into a form using compressed air.
T.	Unit Wall Weight: The unit wall weight is the calculated weight of a 1 x 1 ft (305 x 305 mm) section of wall surface area times the full wall thickness, including finishes. The unit wall weight is the sum of the weight of each constituent material times its volume, expressed as psf.
U.	Void: Any space in a hempcrete wall greater than 1/4 inch (6 mm) wide, 2 inches (51 mm) long and 2 inches (51 mm) deep.
1.5	SUBMITTALS
A.	Submit under provisions of Section 01 30 00.
B.	Product Data:
1.	Manufacturer's data sheets on each product to be used.
2.	Preparation instructions and recommendations.
3.	Storage and handling requirements and recommendations.
4.	Typical installation methods.
C.	Verification Samples: Two representative units of each type, size, pattern, and color.
D.	Shop Drawings: Include details of materials, construction, and finish. Include relationship with adjacent construction.
1.6	QUALITY ASSURANCE
A.	Manufacturer Qualifications: Company specializing in manufacturing products specified in this section with a minimum of 2 to 3 years documented experience.
B.	Installer Qualifications: Company specializing in performing Work of this section with minimum two years documented experience with projects of similar scope and complexity.
1.	Tradesman: Trained by Manufacturer or manufacturer approved training program for the following work results.
a.	Casting.
b.	Spraying.
c.	Precast Blocks.
d.	Panels.
C.	Source Limitations: Provide each type of product from a single manufacturing source to ensure uniformity.
D.	Mock-Up: Construct a mock-up with actual materials in sufficient time for Architect's review and to not delay construction progress. Locate mock-up as acceptable to Architect and provide temporary foundations and support.
1.	Construct mock-up separate and free standing from the main structure.
2.	Mock-up Size: Sufficient to be representative of the final installation.
3.	The intent of a mock-up is to demonstrate quality of workmanship and visual appearance.
4.	If the mock-up is not acceptable, rebuild the mock-up until satisfactory results are achieved.
5.	Retain mock-up during construction as a standard for comparison with completed work.
6.	Do not alter or remove mock-up until work is completed or removal is authorized.
1.7	PRE-INSTALLATION CONFERENCE
A.	Convene a conference approximately 4 to 6 weeks before scheduled commencement of the Work. Attendees shall include Architect, Contractor and trades involved. Agenda shall include schedule, responsibilities, critical path items and approvals.
1.8	PRECONSTRUCTION TESTING
A.	Preconstruction Testing Service: Engage a qualified testing agency to perform preconstruction testing on each hempcrete mixture.
B.	Testing Samples: for determining thermal performance and compressive strength,
1.	Three samples of the proposed hempcrete mix shall be placed moist to completely fill a 6 x 6 x 12 inch (152 x 152 x 305 mm) form, a 6 inch (152 mm) diameter x 12 inch (305 mm) length form or other approved form, following the application method and procedure that will be used during construction.
a.	The samples should be as homogeneous as possible and representative of the final product. When making hand cast samples it is recommended to make at least three layers that are compacted successively. Ensuring the density of the sample is within the expected density range for installation is essential for accurate results.
2.	Samples shall be removed from the forms within 24 hours after hempcrete placement or per the binder manufacturer's specifications.
3.	Samples shall be cured/dried for a minimum of 14 days in indoor ambient conditions before density determination.
C.	Thermal Performance:
1.	The unit R-value of hempcrete may be determined with one of the following tests by an approved laboratory: ASTM C518, ASTM C1363, ASTM C177, or ASTM C1114.
D.	Mechanical Performance:
1.	Infill Integrity and Ability to Hold a Plaster Finish: Must be demonstrated with a minimum compressive strength of 29 psi (0.2 MPa) ensuring the infill has sufficient integrity to carry its own weight and its plaster finish.
1.9	DELIVERY, STORAGE, AND HANDLING
A.	Store and handle in strict compliance with manufacturer's written instructions and recommendations.
B.	Protect from damage due to weather, excessive temperature, and construction operations.
1.10	PROJECT CONDITIONS
A.	Maintain environmental conditions (temperature, humidity, and ventilation) within limits recommended by manufacturer for optimum results. Do not install products under environmental conditions outside manufacturer's recommended limits.
1.	During Installation and Curing:
a.	Maximum Installation Temperature: 80 degrees F (38 degrees C).
b.	Minimum Installation Temperature: 40 degrees F. (4 degrees C).
c.	Allow installation outside temperature limits with adequate protection according to manufacturer guidelines.
1.11	WARRANTY
A.	Manufacturer's standard limited warranty unless indicated otherwise.
PART 2    PRODUCTS
2.1	MANUFACTURERS
A.	Acceptable Manufacturer: Americhanvre, which is located at:<BR />1529 Brookside Rd.<BR />Allentown, PA 18106<BR />Toll Free Tel: 833-443-6727<BR />Email: request info (cameron@americhanvre.com);Web: https://americhanvre.com 
B.	Substitutions: Not permitted.
C.	Requests for substitutions will be considered in accordance with the provisions of Section 01 60 00.
2.2	SYSTEM DESCRIPTION
A.	Hempcrete: A bio-composite non-load bearing building material used in the creation of walls, and roof construction. It is lightweight, breathable, with excellent thermal resistance.
1.	Hempcrete is cast or sprayed around a timber or steel frame that carries the vertical loads of the roof and upper floors.
2.	The high thermal performance and air-tightness means single skin structures are sufficient and do not require additional insulation layers. This avoids the need for cavity wall construction. The ability of the walls to breathe and to store heat allows for passive self-regulation of the temperature and humidity within the building, often reducing heating and air conditioning requirements.
2.3	PERFORMANCE AND DESIGN REQUIREMENTS
A.	General: Buildings with hempcrete walls using the prescriptive provisions in this specification are limited to one-story. Multi-story buildings are allowed with an approved engineered design by a registered design professional.
B.	Performance Requirements:
1.	R Value: Average 2.2 per inch. Density: 14.73 to 15.20 lbs per cu ft
2.	Coverage: 10 cu ft (0.283 cu m) of Hempcrete will cover 10 sq ft (0.929 sq m) of a typical 12 inch (305 mm) thick Hempcrete wall.
3.	Flame Spread Index according to ASTM E84 or UL 723: 25 or less for a Class A rating.
4.	Smoke Development Index according to ASTM E84 or UL 723: 25 or less for a Class A rating.
5.	Comply with the International Residential Code (IRC), Appendix BL unless modified by this specification.
2.4	HEMPCRETE MATERIALS
A.	Hempcrete Mix Design: Typically begins with a desired unit thermal resistance value (R-value/inch). The constituent materials of hemp hurd, binder, and water must comply with the following.
1.	Hemp Hurd: The chopped woody core of the stalks of the hemp plant, stripped of its surrounding hemp fibers. Also known as hemp shiv or shive. See Section BL103.2.1 of the IRC.
a.	Hemp hurd used in construction must match the specifications of the hemp hurd in the approved test samples.
2.	Binder: A material that binds the hemp hurd in a hempcrete mix.
a.	Unites the mix and provides many of its hygrothermal properties, safely managing moisture throughout the matrix while providing thermal mass that complements the thermal insulation of the hemp hurd.
b.	Basis of Design: Ereasy 120 Binder as manufactured and supplied by Americhanvre. Can also be used for cast in-situ builds at a ratio of 1:1 by weight with the hurd. This binder is also certified by the Constuire en Chanvre to be paired with our hurd, providing further reassurance for code officials, builders, and homeowners that the products will perform as specified.
3.	Water and Water Additives: Must match what was used in the approved test samples specified in this section.
PART 3    EXECUTION
3.1	EXAMINATION
A.	Do not begin installation until the substrates have been properly constructed and prepared.
1.	Contact with Metal: Metal in contact with hempcrete shall be stainless steel or primed and painted with epoxy, oil, bituminous paint, or other approved coating. Water based paints shall not be used.
a.	Electrical and telecommunication wiring, panels, and boxes, mechanical ducts, plumbing pipes, and other mechanical, electrical, and plumbing components in or in contact with hempcrete shall be isolated in sleeves, pipes, conduits, or tubing made of plastic, or painted as specified, or separated from hempcrete with an approved alkaline-resistant material.
B.	Verification of Conditions:
1.	Prior to Hempcrete Placement: Before placing, verify installation of forms, accessories, bracing, structure, and embedded items is complete and required inspections are completed.
2.	The structure of buildings using hempcrete infill must be in accordance with the IRC and Sections BL103.3.1 through BL103.3.9 or with an engineered design by a registered design professional and approved by authorities having jurisdiction.
C.	If substrate preparation is the responsibility of another installer, notify Architect in writing of unsatisfactory preparation before proceeding.
3.2	PREPARATION
A.	Clean surfaces thoroughly prior to installation.
B.	Prepare surfaces using the methods recommended by the manufacturer for achieving the best result for the substrate under the project conditions.
3.3	INSTALLATION
A.	Install in accordance with manufacturer's instructions, approved submittals, and in proper relationship with adjacent construction.
1.	Hempcrete shall be installed in accordance with the following sections of the IRC.
a.	Section BL103.6.1: Mix and mixing.
1)	Ratio of Hemp Hurd to Binder to Water: Match the specifications of the approved test samples.
2)	Water to Binder Ratio: Not less than 1:1. Not greater than 2:1 by weight or by binder manufacturer's recommendations.
3)	Hemp Hurd, Binder, and Water: To be thoroughly and uniformly mixed by manual or mechanical means.
b.	Section BL103.6.2: Formwork for hand cast and spray-applied methods.
1)	Forms: Must not deform under lateral pressure from installed wet hempcrete.
a)	Permanent Forms: Remain after curing as a finish or substrate for another finish.
1)	Material: Reed mats, or other approved materials with an open weave to be installed on only one side.
2)	Sheet Materials: Must not be used as permanent forms.
3)	Exception: Permanent forms of any material shall be permitted at the jambs, heads, and sills of openings.
b)	Removable Forms: Removed within 24 hours after hempcrete placement or per the binder manufacturer's specifications.
1)	Exception: Removable forms temporarily supporting hempcrete infill above wall openings shall not be removed for a minimum of 3 days or per binder manufacturer's specifications.
c.	Section BL103.6.3: Hand Cast. Installed in uniform lifts not greater than 4 inches (102 mm) in height. Each lift shall be tamped to achieve stable walls free of voids.
d.	Section BL103.6.4: Spray-applied. Forms to be installed on one side in accordance with Section BL103.6.2
1)	Mixing: In accordance with Sections BL103.6.1 or the spray equipment manufacturer's instructions.
2)	Installation: Hempcrete to be sprayed from the base up and per the spray equipment manufacturer's and/or binder manufacturer's instructions.
3)	Screeding: Excess hempcrete to be removed by screeding per the spray equipment manufacturer's and/or binder manufacturer's instructions.
e.	Section BA103.6.5 - Precast Blocks.
1)	Block Dimensions:
a)	Minimum Thickness: 3 inches (76 mm) in all dimensions
b)	Maximum Thickness: Limited by the average unit wall weight limit of 65 lbs per sq ft (317 kg per sq m).
2)	Casting: In accordance with Sections BL103.6.1 through BL103.6.6 as applicable, or by other means that produce approved blocks.
3)	Mortar: To consist of lime and sand or other aggregate with a ratio of not less than 1:1 and not greater than 1:3, or other approved mortar. The lime shall be hydrated Type N or S, or hydraulic lime mixed with a pozzolan or hydraulic component.
4)	Installation: A running bond between and around wall framing members. Mortar is to fill all voids between blocks and shall not be less than 1/8 inch (3 mm) thick. Spaces between blocks and framing must not be more than 3/4 inch (19 mm) and filled with mortar.
5)	Hempcrete Block Veneer:
a)	Not to exceed 50 lbs per sq ft (244 kg per sq m) of veneer only unit wall weight.
b)	Limited to 5 inch (127 mm) thickness.
c)	Anchored to the supporting wall studs in accordance with Section R703.8.4 of the IRC or secured with approved ties and fasteners to an approved backing.
d)	Metal Ties and Fasteners: Stainless steel or primed and painted with epoxy, oil, bituminous paint, or other approved coating. Water based paints shall not be used.
f.	Section BL103.6.6: Hempcrete panels. Hempcrete panels shall require an approved design by a registered design professional.
1)	Panels to be built by the hand cast or spray applied method in this specification.
2)	When fabricated off site, panels are to be cured per the manufacturer's instructions before transportation to the project site.
g.	Section BL103.6.7: Lined applications.
1)	Interior and exterior hempcrete lined applications are to be installed in accordance with the following:
a)	General: Prior to installation, the concrete or masonry walls receiving the installation shall be clean, and free of loose mortar.
1)	Lined Installations on Basement Walls: Require an approved design by a registered design professional.
2)	Exterior Applications: Hempcrete to be 8 inches (203 mm) above exposed earth or paved areas.
3)	Attachment of Precast Blocks to the Receiving Wall: shall be in accordance with Section BL103.6.5.5.
4)	Attachment of hempcrete panels to the receiving wall shall be in accordance with Hempcrete block veneer in this specification.
b)	Formwork. To be in accordance with Section BL103.6.2.
1)	Permanent Formwork: Not to be allowed on the non-receiving wall side.
c)	Thin Lining: From 3 to 4-1/4 inches (76 to 121 mm) thick.
1)	Hand Troweled Hempcrete: Installed over a bonding coat.
2)	Spray-Applied Hempcrete: Bonds sufficiently to the receiving wall without a bonding coat.
d)	Medium Lining: Exceed 4-3/4 inches (121 mm) and are not greater than 6-1/2 inches (165 mm) thick.
1)	Hand Cast or Spray-Applied: 1-1/2 x 1-1/2 inch (38 x 38 mm) dovetail shaped vertical anchorage rails to be attached with the narrowest face to the receiving wall, spaced not less than 20 inches (508 mm) and not greater than 32 inches (813 mm), with fasteners not less than 2 ft (610 mm) and not greater than 3 ft (914 mm) apart.
2)	To be installed over a bonding coat on the receiving wall.
e)	Thick Lining: Exceeds 6-1/2 inches (165 mm) and not greater than 8 inches (203 mm) thick or per the binder manufacturer's specifications.
1)	Hand Cast or Spray-Applied: 1-1/2 x 2-1/2 inch (38 x 64 mm) vertical anchorage rails attached with the 2-1/2 inch (64 mm) face parallel to the receiving wall and spaced not less than 20 inches (508 mm) and not greater than 32 inches (813 mm).
2)	Anchorage Rails: Fastened to and separated from the receiving wall with 2 inch (51 mm) spacers not less than 3 ft (914 mm) and not greater than 4 ft (1,219 mm) apart.
a)	Minimum Anchorage Rail Thickness: Between the exterior face of vertical anchorage rails and finished face of hempcrete to be 3 inches (76 mm) or in accordance with the binder manufacturer's specifications.
3)	To be installed over a bonding coat on the receiving wall.
3.4	FIELD QUALITY CONTROL
A.	Field Inspection: Coordinate field inspection in accordance with appropriate sections in Division 01.
B.	Manufacturer's Services: Coordinate manufacturer's services in accordance with appropriate sections in Division 01.
3.5	CLEANING AND PROTECTION
A.	Clean products in accordance with the manufacturers recommendations.
B.	Touch-up, repair or replace damaged products before Substantial Completion.

END OF SECTION