Key Elements of CMU Rebar Shop Drawings: What Contractors Should Know

When it comes to masonry construction, CMU (Concrete Masonry Unit) is often chosen over other materials because of its combination of strength, ease of construction, and low cost. For contractors, ensuring the accuracy and clarity of CMU rebar shop drawings is essential for successful project execution. The shops serve as the guidelines for placing reinforcing steel within the masonry, and any oversight within the shops can lead to costly errors, delays, or code compliance issues. That’s why partnering with a professional provider of CMU rebar shop drawings, like us here at DraftingServices.com, can make all the difference in your project’s success. Here’s a breakdown of the critical elements these drawings should include and how we can help ensure your project’s success.

Here are the actual CMU shop drawings we drafted for this project.

The Fundamentals

When discussing CMU construction, we’re normally focusing on CMU walls. With this said, the fundamental elements of any CMU rebar detailing project include the following.

1. Rebar Placement

At the heart of any CMU rebar shop drawing is the precise placement of reinforcing bars. Our expertly crafted drawings clearly indicate:

• Horizontal and Vertical Rebar Placement: Exact locations of horizontal and vertical rebar within the CMU wall to meet structural design requirements and provide the necessary strength and stability.

• Wall Elevations: Elevation views that depict rebar layout for easy visualization of spacing and continuity.

• Typical CMU Details and Cross Sections: Inclusion of typical reinforcement details and cross-sectional views to clarify rebar placement at complex areas such as corners, intersections, and openings.

• Bar Schedules: Detailed bar schedules listing sizes, lengths, and quantities of rebar to ensure accurate ordering and installation.

• Lap Schedules: Specific details outlining where and how lap splices should be made to maintain structural integrity and adhere to code requirements.

• Call-Out Key Plan: A comprehensive key plan that shows how to read the shop drawings’ notations that include placing remark, bar lenght ro mark no., bar size, quatity per location, and locations required.

2. Dowel Alignment

Dowels connect CMU walls to foundations, slabs, or adjacent structural elements. Our shop drawings detail:

• Dowel Locations: Precise measurements to avoid misalignment during installation.

• Embedment Depth: Required embedment depths into the foundation or other structural elements to ensure proper anchorage.

• Field Adjustments: Notes on tolerances and allowable field adjustments to account for on-site variations.

3. Lap Splice Details

Lap splices are necessary in instances when full-length rebar cannot be used. The term “lap” is short for overlap. The lap splice is a form of a connection. The lap length is dictated by code ACI 530 unless indicated otherwise in the contract drawings. Laps develop the strength of the connection. Our drawings ensure:

• Clearly Defined Lap Splice Lengths: Adherence to code requirements, based on rebar size, grade, and anticipated loads.

• Identified Locations: Clear indications of splice locations to avoid clustering or compromising strength.

• Staggering Requirements: Splices are staggered where applicable to minimize weak points in the reinforcement.

4. Lintels

Lintels are horizontal structural elements used to support loads above openings like windows and doors. They play a crucial role in maintaining the structural integrity of CMU walls by distributing load around openings. In our drawings we note all lintel locations, and their bearing lengths on the sides of openings.

There are three primary types of lintels:

• Cast-in-Place Lintels: Constructed on-site, these lintels use rebar and concrete poured into forms. They are versatile and can be customized to meet specific structural requirements.

• Precast/Prestressed Concrete Lintels: Manufactured off-site, these lintels incorporate cast steel tendons for temporary support during placement. Once installed, additional rebar and grout are added to integrate them with the surrounding masonry.

• Steel Lintels: Fabricated from steel, these lintels must comply with ASTM A36 standards. Steel angle lintels, commonly used in CMU construction, should be at least 1/4 inch thick. They are ideal for projects requiring durability and resistance to high loads.

Our firehouse shop drawings above include a variety of steel lintels at all door and window openings. There were also bond beams on this project, but they were not used as lintels to distribute loads around openings.

5. Code Compliance

Adherence to local, state, and national building codes is non-negotiable in CMU construction. The architect-of-record is responsible for establishing what codes should be followed. Our shop drawings comply with such codes, and those could include:

• International Building Code (IBC)

• American Concrete Institute (ACI) ACI 530/ASCE 5/TMS 402, Latest Edition “BUILDING CODE REQUIREMENTS FOR MASONRY STRUCTURES”

• Mortar conforming to the requirements of ASTM C-270

• All welded reinforcing shall be ASTM A706

• Reinforcing bars conforming to ASTM A615, GRADE 60

• Lap reinforcing in accordance with ACI 530

6. Clarity and Presentation

Beyond technical content, the effectiveness of shop drawings often lies in their clarity. We ensure:

• Standardized Symbols: Consistency and prevention of misinterpretation by adhering to recognized industry symbols and notations.

• Section Views and Details: Enlarged views of critical areas, such as corners, intersections, and openings, to avoid ambiguity.

• Legends and Notes: Clear explanations of all symbols, abbreviations, and special instructions.

Partner with DraftingServices.com for Your CMU Rebar Shop Drawings

We specialize in providing detailed, accurate, and code-compliant CMU rebar shop drawings tailored to your project’s needs. Our expertise ensures that every detail is accounted for, from technical content to readability. Let us handle the complexities of your shop drawings so you can focus on building with confidence.

Contact

Contact us today to learn more about our drafting services and how we can support your next project! We can be reached now at 718.441.3968, text us now at 646.504.5230, or email us now at [email protected].