Frequently Asked Questions

Johnson Concrete Products answers your most common questions on masonry, block, and outdoor living solutions.

Product Standards & Technical Questions

Q: What’s the difference between ASTM C90, ASTM C1364, and ASTM C144?

A: ASTM C90 defines performance standards for concrete masonry units (CMU)—covering compressive strength, shrinkage, dimensional tolerance, and absorption. ASTM C1364 is the standard specification for architectural cast stone, that sets the requirements and guidelines for the manufacturing, testing, and installation of architectural cast stone products. ASTM C144 outlines the specification for aggregates used in mortar, helping ensure reliable mortar performance in masonry systems.

Q: What type of mortar should I use for concrete masonry?

A: Mortar for concrete masonry is typically specified as Type M, Type S, or Type N under ASTM C270.

  • Type M offers the highest compressive strength and is often used for foundations, retaining walls, and other heavy loads.
  • Type S balances strength and workability, making it a common choice for structural walls.
  • Type N provides good workability and weather resistance, and is widely used in above-grade, non-load-bearing walls and veneers.

Learn more from CMHA: Mortars for Concrete Masonry – TEK 09-01A

Q: Does the size and configuration of CMU affect compressive strength?

A: Yes. The compressive strength of concrete masonry is influenced by several factors, including unit size, shape, and density (pounds per cubic foot, or PCF). These characteristics affect the net cross-sectional area of the wall and the strength of the individual units, which together determine overall wall capacity. For detailed reference data on weights and section properties, see CMHA’s CMU-TEC-002 – Weights and Section Properties of Concrete Masonry Assemblies

Q: Do clay brick and concrete block expand or shrink at the same rate?

A: No. Clay brick usually expands over time from moisture, while concrete block generally shrinks as it dries. Designers account for this by using joints and detailing to manage movement. Learn more from CMHA: CMU-TEC-009 – Crack Control for Concrete Masonry Walls

Q: What’s the difference between Type 1 and Type 2 CMU block?

A: Prior to 2000, ASTM C90 included two different type designations for concrete masonry units: Type I units were defined as moisture-controlled units; Type II units were defined as non-moisture controlled units. The requirements for these two different unit types were identical in all respects with one exception: the moisture content of the unit at the time of delivery. In 2000 ASTM removed Type 1/Type 2 unit designations.

Q: Does an 8x8x16 block have a 2-hour fire rating?

A: Not always. Johnson Concrete Products’ standard 8x8x16 lightweight commercial block does have a 2-hour fire rating. Most normal weight and medium weight, and some lightweight 8x8x16 blocks do not have a 2-hour fire rating. Fire ratings depend on block material and equivalent thickness. Lightweight aggregates like Stalite improve fire resistance. According to the CMHA, fire ratings are determined using formulas like ASTM E119 and equivalent thickness—not solely unit size. Learn more from CMHA: Fire Resistance Ratings of Concrete Masonry Assemblies – CMHA

Architectural Masonry Systems & Innovations

Q: What is Water Control Technology in masonry block?

A: Water Control Technology improves moisture resistance in CMU wall assemblies without compromising block strength or performance. The technology involves subtle changes to the top surfaces of each WCT block’s webs to discourage water from crossing to the interior face shell. WCT units feature integral drainage zones that direct moisture to the wall’s drainage system. Many of our architectural units feature this enhanced water management capability.

Q: What is the Spec-Thermal Pre-Insulated Masonry Wall System?

A: The Spec-Thermal™ system, offered through Johnson Concrete Products as a member of Concrete Products Group (CPG), is a high-performance pre-insulated masonry wall solution with structural CMU and built-in insulation. It supports energy-efficient commercial design with exposed masonry on both sides.

Q: What is Hi-R-H?

A: Hi-R-H® is a fully grouted, pre-insulated masonry wall system ideal for double-exposed single wythe walls. It performs well in conditioned spaces across all climate zones and is part of Johnson’s high-R-value product lineup.

Design Tools & Support

Q: Do you offer tools for designing masonry walls?

A: Yes. Johnson Concrete Products provides access to the CPG Masonry Designer Software, allowing you to visualize block textures, colors, and mortar combinations. Additional resources are available for architects and specifiers. Learn more.

Q: Do you offer educational resources on masonry systems?

A: Yes. We offer training and continuing education programs covering best practices in masonry design, construction techniques, thermal efficiency, and more—ideal for architects, engineers, and contractors. Learn more.

Installation, Quantities & Material Estimations

Q: How many concrete blocks do I need per square foot of wall?

A: For a standard 8×16 CMU wall, estimate about 1.125 blocks per square foot (roughly 113 per 100 ft², excluding waste). Learn more from CMHA: TEK 04-02A – Estimating Concrete Masonry Materials

Q: How much mortar and sand do I need?

A: Approximate usage for 75 pound bag of mortar where sand is added on-site:

  • 33 concrete blocks
  • 142 modular bricks
  • 118 engineer bricks
  • 1 ton of sand per 6 bags of mortar

Approximate usage for 80 pound bag of mortar where sand is pre-blended:

  • 12 concrete blocks
  • 40 modular bricks
  • 33 engineer bricks

Check out our Materials Estimator.

Q: How often should I place control joints in CMU walls?

A: Control joints are typically spaced at 1½ to 2 times the wall height, not exceeding 25 feet, with additional joints at changes in height, length, or around openings. Learn more from CMHA: CMU-TEC-009 – Crack Control Strategies

Q: How far should precast lintels extend past an opening?

A: Minimum 8″ on each side (or 4″ for Cast-Crete lintels).

Q: Can I use regular mortar for grouting?

A: No. Use fine or coarse grout for bond beams, door jambs, and filled cores.

Q: Can I use hot-dip or mill galvanized wire?

A: Use hot-dip galvanized wire for exteriors; mill galvanized is acceptable for interior applications.

Q: How often should wall ties be placed?

A: Install at 16″ horizontal and 12–24″ vertical spacing, per building code.

Cleaning & Maintenance

Q: What is the best way to clean decorative concrete masonry?

A: Use a mild detergent masonry cleaner (e.g., EaCo Chem NMD 80 Detergent or ProSoCo Custom Masonry Cleaner) per manufacturer’s instructions. Avoid high-pressure washing, pre-soak with water, and always test a small area first. Learn more from CMHA: TEK 08-04A – Cleaning Concrete Masonry

Hardscapes, Brick & Stone Products

Q: Do you sell hardscaping products or manufactured stone veneer?

A: Yes. We offer segmental retaining wall systems, pavers (concrete, brick, porcelain), clay brick, fire pit kits, and a full line of manufactured stone veneer for residential and commercial landscapes.

Q: What types of retaining wall systems do you offer?

A: We produce and stock SRW systems in multiple shapes, sizes, finishes, and colors—designed for both decorative and structural uses.

Q: What brick options are available?

A: We carry a wide range of clay brick from leading manufacturers, available in multiple sizes, colors, and finishes. Sold in full pallets; some pickup options available.

Q: Do you offer fire pit kits?

A: Yes. Our ready-to-install fire pit kits come in a variety of materials and finishes. Perfect for DIY projects and professional installs.

Drainage Products & Pipe

Q: Do you sell concrete culvert pipe or RCP?

A: Yes. We manufacture Reinforced Concrete Pipe (RCP) in Salisbury, NC. Common sizes: 15″, 18″, 24″ (4-ft and 8-ft lengths). We stock 8-ft lengths in Salisbury only and 4-ft lengths at our other locations. Call for pricing and availability. 

Q: Is 8-foot driveway pipe available?

A: Yes, produced in Salisbury. Custom sizes, flared ends, and stormwater pre-cast available by request. Call for pricing and availability. 

Q: Do you carry flared end sections?

A: Yes. Flared ends and stormwater pre-cast available by request. Call for pricing and availability. 

Retail, Delivery & Sales Support

Q: Do you sell to the public?

A: Yes. Contractors and homeowners are welcome. Visit any of our plants to view products or place orders.

Q: Can I pick up products myself?

A: Yes. With an appropriate vehicle, you can pick up CMU, mortar, accessories, or hardscaping materials at any location.

Q: Do you deliver?

A: Yes. We offer local and long-distance delivery using trucks with Moffett forklifts for easy on-site unloading. 

Q: What is your return policy?

A: Unused block in resalable condition may be returned for a restocking fee. Mortar, cement, and special order items are non-returnable. Clearance/seconds sales are final.

Q: Do you install your products?

A: No. We do not offer installation but can recommend trusted contractors and masons in your area.

Q: Do you have showrooms?

A: Yes. Visit any of our plants to view products or place orders.

Q: Do you offer credit accounts or financing?

A: Yes. Contractors can apply for credit. 

Q: Are you open on weekends?
A: Some plants are open on Saturdays during peak season. Call your local plant for hours.

General Information & Locations

Q: Where are your manufacturing plants located?

A: We operate six plants:

Q: How long has Johnson Concrete Products been in business?

A: Since 1947. We are a 100% women-owned, fourth-generation family business.

Q: Where can I browse your products or get more information?

A: Visit johnsonproductsusa.com to explore our full product catalog and request a quote.

Q: Can I meet with a sales representative?

A: Yes. Our team is available for job site visits, design consultations, and one-on-one meetings.