Submittal
Submit samples for selection from manufacturer's standard series. Submit product literature, certifications, test reports, and full size sample(s) of each unit specified.

Quality Assurance
Certifications: Concrete blocks shall conform to ASTM C90, TYPE 1. The provisions of ASTM C90 Paragraph 7.3.1 apply with regard to imperfections. Concrete "Green Block" shall meet recycled content values of no less than 10 percent of the total value in accordance with USGBC MR Credit 4.2 requirements for LEED certification.

Fire Resistance: Define hourly rating required as 1, 2, 3, or 4 hours.

Project/Site Conditions
Protection of work: Cover walls each day after installation to keep open walls protected and dry.

PART 2-PRODUCTS
Product Name
Recycled Content LEED certified "Green Block".

Manufacturer
York Building Products Company • 950 Smile Way, York, PA 17404 • 800-673-2408 • 717- 848-2831 • FAX 717-854-9156

Sizes And Shapes
Nominal 6", 8", 10", and 12" standard block thicknesses are available.

Water Repellency
"Green Block" units required to meet water repellency specifications will be manufactured with W. R. Grace DRY-BLOCK water repellent admixture.

Units not required to meet water repellency specifications will be manufactured with a trace amount of W.R. Grace DRY-BLOCK water repellent admixture to assist in controlling efflorescence. This however does not make the product water repellent. Utilization of W.R. Grace DRY-BLOCK mortar admixture therefore will not make the wall system water repellent in the absence of a full load of DRY-BLOCK used during the manufacturing process of the "Green Block" unit.

PART 3-EXECUTION
Laying Masonry Walls
Lay units using the best concrete masonry practices. Install only quality units; reject all defective units. Align units level, plumb and true with uniform carefully tooled 3/8" wide joints on the textured face side of the wall. Draw blocks from more than one pallet at a time during installation. Use W.R. Grace DRY-BLOCK water repellent mortar admixture, following manufacturer's instructions in all exterior mortar.

Installation
Cutting: Make all unit cuts, including those for bonding, holes, boxes, etc. with motor driven masonry saws, using either an abrasive or diamond blade. Cut neatly and locate for best appearance.

Inspection
The block shall be free from chips, cracks, crazes or any other imperfection that would detract from the overall appearance of the finished wall when viewed from a distance of twenty (20) feet at right angles to the wall with normal lighting.

Flashing Of Masonry Work
Install flashing at locations shown in the plans and in strict accordance with the details and the best masonry flashing practices using flashing specified by the architect.

Weep Holes And Vents
Install weep holes and vents at proper intervals (32" O.C. and 2" long above bed joints), typical at courses grade, above flashing, and at any water stops over windows, doors and beams.

Pointing
Tuck point the joints of "Green Block" units.
Raked joints are not recommended for any application.

Cleaning
Keep walls clean daily during installation with masonry brushes and wooden or plastic scrapers. Do not allow mortar lumps or smears to harden on the finished surfaces. Harsh cleaning methods used after completion may mar the surface of the block.

Final Cleandown
Clean the completed walls with a detergent masonry cleaner strictly following the manufacturer's instructions including thorough rinsing. Do not use acid or abrasives on the finished surfaces.

Maintenance
"Green Block" units if properly installed will require little or no maintenance. Some inks, stains or graffiti may require special cleaning methods. Contact the manufacturer for recommended cleaning products and procedures when addressing abnormal stains, graffiti, etc.

Recommendations

•	Always test a small inconspicuous area before using cleaners.
•	Matching mortar colors are recommended for architectural masonry units.
•	Do not use acids or abrasives on finished surfaces.
•	Use motor driven masonry saws with abrasive or diamond blades for cutting all concrete masonry units.