Updated on March 13, 2024


Created on September 1, 2021

Watershed Block

Watershed Blocks are alternatives to building blocks made of recycled materials using less cement.

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Product Description

Watershed Materials has developed a technology to use up to 100% locally sourced recycled material as aggregate for an alternate masonry block. They use post-industrial recycled materials – without washing or intense processing – to produce masonry blocks. Watershed Materials technology incorporates no colorants, dyes, or artificial pigments. Surface finishes are not required, eliminating concerns over volatile organic compounds (VOCs) and other harmful coatings. The technology allows for natural clay found readily all over the planet to be turned into sustainable masonry products.

Target SDGs

SDG 11: Sustainable Cities and Communities

SDG 12: Responsible Consumption and Production

Target Users (Target Impact Group)

Household, Small and Medium-sized Enterprises

Distributors / Implementing Organizations

Watershed Materials distribute the product

Competitive Landscape

Manufacturing/Building Method

Watershed Block is produced in San Francisco Bay Area, CA, USA

Intellectural Property Type


User Provision Model

The manufacturer provides the customers with the blocks, directly. The blocks are intended to be used within a 250-mile radius of the San Francisco Bay Area. However, with carbon offset credits, it can be transported worldwide.

Distributions to Date Status

Stanford Lasuen, Sonoma Residence, and Napa Residence are examples of using this product in real-life scenarios.

Unit dimensions (cm)

Available in several dimensions

Primary materials

Natural Geo-polymers, Lime, and Slag

Complimentary materials

Natural Aluminosilicates, and Rice Husk

Fire Resistance (hr)


Thermal Insulation Capacity

0.81–0.93 W/m°C

Compressive Strength (MPa)

9~13 MPa

Suitable Climates

All Climates

Design Specifications

There are six different block types manufactured that vary in their shape and dimensions. 3 are regular blocks, 2 are bond-beam blocks, and the last one is a cap for the blocks. The entire process for using the material for installation is explained below: Preparation 1. Establish lines, levels, and coursing

  • Protect lines from disturbance.
  • Use non-corrosive materials in contact with masonry.
2. Surface preparation
  • Before placing masonry units, remove loose aggregate or any other materials to prevent mortar from bonding to the foundation.
3. Layout
  • Layout walls in advance for accurate spacing of surface bond patterns with uniform joint thicknesses and accurate location of openings, movement-type joints, returns, and offsets. Where possible, avoid using units cut to less than half size, particularly at corners and jambs
Construction 1. Coursing and bonding
  • Place masonry units to lines and levels indicated on project drawings.
  • Maintain masonry coursing and horizontal joints of uniform width and thickness.
  • Place masonry units in running bond pattern unless otherwise noted on project drawings.
  • Course one masonry unit and one mortar joint to equal 203 mm, 152mm102 mm.
2. Mixing and placing mortar
  • Mix mortar following the requirements of ASTM C270-12a.
  • Discard mortar not used within 2-1/2 hours of initial mixing.
  • Construct 9.4 mm bed and head joints with the minimum depth of masonry unit face shell, unless otherwise indicated on Project Drawings.
  • Construct bed joint at starting a course on a foundation not less than 7 mm and not more than 19 mm.
  • Use tuck-pointing procedures as specified in ASTM C270-12a to fill voids in below grade and exposed masonry.
  • Tool head and bed joints with a concave profile for all masonry exposed to exterior weather conditions unless alternate joint treatments are specified.
  • Remove masonry protrusions extending 12.5 mm or more into cells or cavities to be grouted.
3. Placing masonry units
  • Do not install masonry units that are cracked, broken, or chipped more than tolerances.
  • When possible, orient masonry units so that small chips, cracks, and minor imperfections are not visible on the exposed side of the walls.
  • Pull colored masonry units from at least three (3) different pallets for proper blending and appearance.
  • Clean units of surface dirt and contaminants before placing them in contact with mortar.
  • Vertical cells to be grouted must be aligned and have unobstructed openings for grout.
  • Remove excess mortar before it hardens and place units such that mortar does not run down the face of the wall or smear into the masonry face.
4.  Adjustments
  • Do not shift or tap masonry units after the mortar has taken the initial set.
  • Where adjustments must be made, remove mortar and replace.
  • Protect wall cavities during construction to prevent excessive moisture ingress.
  • When beginning work each day, clean masonry surfaces, receive mortar and remove loose masonry units and mortar.
5. Anchorage 6. Control 7. Sealing Joints 8. Grout Placement 9. Cleaning
  • Clean masonry units as work progress by dry brushing to remove mortar fins and smears before tooling joints.
  • Clean exposed architectural masonry with approved cleaners, as per the manufacturer’s recommendations. Clean masonry before installing windows, doors, finished flooring, metal fixtures, hardware, light fixtures, roofing materials, and other non-masonry items.
  • All surfaces shall be clean, dry, and free of scale, mud, or efflorescence, and cracks shall be filled before applying the water-repellent coating. Apply water-repellent coating to wall surfaces in strict accordance with manufacturer directions. Protect adjacent surfaces and work from damage and staining throughout the application of the water-repellent sealer.

Product Schematics

Technical Support


Replacement Components

The entire block is replaceable.



Manufacturer Specified Performance Parameters

The manufacturer aims to reduce the cement use by 100% and use up to 100% locally-sourced recycled materials to manufacture the blocks.

Vetted Performance Status

There is no explicit information on third party organization testing, however the manufacturer requires users as per the specification to test the units according to ASTM C140/140M-14, ASTM C90-14 and ASTM C426-10 and to send back in the event of any defect in the units.


No known safety hazards are related to this product.

Complementary Technical Systems


Academic Research and References

Compliance with regulations

The manufacturer tested the product based upon The Masonry Society (TMS) standard TMS 602, a CSI-format, three-part specification as adapted by the American Concrete Institute (ACI), and incorporated by reference in the California Building Code (CBC).

Other Information

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