steel

Steel Detailing: Connecting to Nonsteel Surfaces

Often in steel detailing, we need to show steel elements that connect to non-steel surfaces, such as concrete, CMU (cement blocks,) wood, or even drywall (provided that the proper blocking is provided inside the stud wall.) This article will discuss how to select and show the proper connectors on shop drawings, erection diagrams, and how to list them in bills of material or field bolt lists.

We are detailers, not Engineers. As such, we do not determine fastener diameter, length, or embed depth. If these parameters are not specified in the contract documents, the detailer may suggest a detail, but will need to flag it for verification by the responsible Engineer, either through the RFI or approval process.

Here are the most common fasteners used to connect steel to other surfaces:

expansion bolts

Expansion bolts or expansion anchors are a category of fastener which is inserted into a pre-drilled hole in a surface, and has a mechanism which expands when tightened. The mechanism, once tightened resists pull-out to secure the connected material to the wall or floor surface. The expansion product specs should be consulted before using to connect in an overhead surface application.

adhesive anchors
[Image: via. Click to enlarge.]

Adhesive anchors are fasteners where a pre-drilled hole in a surface is injected with an adhesive material and a threaded rod or a specialty anchor rod is inserted. Once cured, the adhesive resists pull-out to secure the connected material to the wall, floor or overhead surface.

lag screw
[Image: via]

Lag screws are basically very large wood screws with a hex head.

The detailer’s responsibility with these fasteners is to show and describe them with enough information that the fabricator can order the precise type and quantity of anchors required. The detailer may do this on erection diagrams, bills of material, and/or field bolt lists. In the case of adhesive anchors, a shop detail may be required if the fabricator plans to cut the threaded rods to length in their own shop.

Here is an example of an adhesive anchor detail and its shopbill information:
adhesive anchor detail
Note that embedment depth must be given so purchaser will know how much adhesive is required.

The steel detailer should also know which expansion anchors are appropriate for which situation:
fastener choice

Especially in misc metals detailing, the connection devices are not always specified in the contract documents. Again, we are not engineers, so selections made by the detailer need to be on the detail drawings submitted to the design team for their approval.

ladder fasteners
[Click to enlarge] Detail of a roof access ladder with three different types of fasteners.

Contract documents often specify a certain brand of expansion anchor or adhesive to be used, but often the option is also given to provide an “or equal” product. In order to give the fabricator’s purchasing department the leeway to make such an “or equal” substitution, use the generic term for the fastener type on the erection and detail sheets. For instance use “wedge anchor,” instead of “Hilti KWIK Bolt 3.” However, it is important to note on the bolt list or bill of materials the specified product, so the purchaser will know what they have to match with their substitution.

fb list
Example field bolt list entries. The main thing is to include all the information necessary to order the correct fasteners.

To further make the purchasing department’s job easier, it is important to select expansion anchors in appropriate and available lengths. (They don’t come in the same 1/4″ increments as regular high strength bolts.) Consult the manufacturer’s selection to find available lengths. For example:

*This is not a paid advertisement for Hilti or Red Head, just pointing to some useful materials.

drop-in
[Image: via.]

Other types of expansion devices to mention are lead shields and drop in anchors. These devices are separate from the bolt or screw itself. They are inserted into a drilled hole, and expand either with a special tool, or when a fastener is threaded into them. These are useful in misc metal or other applications where the connection is exposed to view, and a plain bolt or screw head will give a cleaner look than a nut with threaded bolt sticking through it.

The last area of concern for the steel detailer are hole sizes in the steel to be connected with these fasteners. Unless oversized or slotted holes are specified in the contract documents, generally hole sizes will be standard 1/16″ larger than the fastener diameter. The only exception being with adhesive anchors: if the steel piece is to be used as a template to drill holes for adhesive anchors the holes will need to be oversized 3/16″ larger than the rod diameter. Again, ensure this is noted on drawings submitted for approval of the EOR. It is always a good idea to consult the fastener manufacturers’ materials to confirm hole size requirements.

The intent of this post has been to give some guidelines for detailing steel attachment devices. Requirements vary from brand to brand, and product line to product line. The internet is your friend. All of the manufacturers post tons of specifications and technical data on these products. A little research is all it takes to get it right the first time when submitting this information for approval. Project Managers and Purchasers will appreciate the effort to make their lives easier… Well, at least they won’t be cussing the detailer out when they have to track down the information themselves.

Scope Of Work: Structural Steel Vs. Miscellaneous Metals

Scope of work is key to any construction contract. It can be a disaster to miss a scope item at bid time which you are responsible for later. Almost as bad, is doing extra work that was not included in your or your client’s scope. So, the first step in any steel detailing project is a scope review. And especially with miscellaneous steel detailing, it’s a good idea to do this review at bid time and include a thorough and specific scope list in your proposal.

Ideally, your client will provide you with their scope list at the time of bid. Absent a client document, the only way to generate a good scope list is a thorough review of all of the contract design drawings, specifications, and addenda. This process is only complicated when the structural steel and miscellaneous metals are split between two different fabricators, or two different detailing outfits. This leads to push and pull between the parties as to which components are considered to be miscellaneous metals and which are structural steel.

The structural scope is easier to determine because structural steel is defined pretty clearly in the AISC Code of Standard Practice:

2.1. Definition of Structural Steel
Structural steel shall consist of the elements of the structural frame that are shown and sized in the structural design drawings, essential to support the design loads and described as:

Anchor rods that will receive structural steel.
Base plates, if part of the structural steel frame.
Beams, including built-up beams, if made from standard structural shapes and/or plates.
Bearing plates, if part of the structural steel frame.
Bearings of steel for girders, trusses or bridges.
Bracing, if permanent.
Canopy framing, if made from standard structural shapes and/or plates.
Columns, including built-up columns, if made from standard structural shapes and/or plates.
Connection materials for framing structural steel to structural steel.

…

[AISC Code of Standard Practice, section 2.1]

The list goes on from there, but it’s enough to say that the phrase, “if attached to the structural steel frame,” figures prominently in nearly every item. So, if structural steel is any steel that is integral to, or attached to the skeleton, or armature if you will, of the building, then miscellaneous steel is, well, everything else. Stairs, railings, ladders, loose lintels, and hundreds of odds and ends made out of steel. And there are often gray areas. For instance, door frames are usually considered miscellaneous, though they often do attach to the structure.

Ultimately, the only way to hash this all out is communication. Communicate with your client to understand their requirements and expectations, and provide feedback in the form of a detailed scope list at bid time. This is the best way for all parties to understand exactly what work is to be performed, and your approved proposal document will serve as a means to resolve any scope issues that may arise during the project.

What Is Steel Detailing?

Steel Project Flow

“What do you do for work?” The often asked ice-breaking question can be difficult for those of us in obscure or somewhat esoteric occupations. What does a steel detailer do?

The small-talk answer is something like, “I’m in construction. I do drafting for steel fabricators. Beams, columns, stairs, rails. Stuff like that.”

The response to which is invariably, “Oh, so like an Architect.”

Well, no. But yes. We do make drawings that people use to build things. But, as I like to gently rib my Architect friends and associates, “The difference between detailers and an Architect is that our drawings have to actually work out in the real world.”

I jest! But it is for this reason, that the Architect comparison rankles many detailers. Because Architects work in broader strokes on the overall design, they have the grass-is-always-greener ‘luxury’ of not having to worry about every last thing that happens inside the walls, or exactly where that HVAC duct has to come up through the roof, and so on. But it’s right there in our title: detailer. We fret over all the little details. So, what is the non-small-talk answer as to what a steel detailer does?

Steel detailers work, either directly as an employee, or on a sub-contract basis, for steel fabricators. Mainly, at least in the past, fabricators expect detailed shop drawings illustrating how to make each steel part required for a construction project. Each beam, each column, each diagonal brace. Stair stringers, railings. Trusses, transfer girders. Every steel outrigger, strut, hanger, spandrel, ledger, slab edge, lintel, ladder. Roof frames, door frames, sump pit frames, canopy frames. And on and on. But it’s not just a matter of generating shop drawings.

All of the steel components must meet the Architectural and Structural requirements in the construction design drawings. They must work together with each other. And they must work together with the components of other building trades. Beyond shop drawings, often the fabricator will require advance material lists for ordering raw materials, CNC and other electronic files for programming their machinery, material files for production tracking software, a BIM model for project coordination, separate sub-assembly details for making common and standard parts, bolt ordering lists, and/or bolt placement lists.

The steel detailer is also often expected to manage the RFI (Request For Information) process with the General Contractor, to resolve conflicts, get necessary information, and coordinate with other subcontractors. The detailer also works with the General Contractor and design team through the approval process, where the Architect and Engineer review and sign off on the completed shop drawings. The detailer also coordinates efforts with the fabricator’s shop personnel, Professional Engineer, material suppliers, joist and deck manufacturer, and erector to ensure it all comes together smoothly.

Essentially, steel detailing is the translation of pertinent project requirements into a format that can be used to instruct the manufacture and installation of components required under the steel fabricator’s scope of work.

And there is absolutely no room for error. Field repairs due to fabricated steel that is the wrong length, connection material welded in the wrong place, holes of the wrong size or in the wrong location, can quickly result in hundreds or thousands of dollars in additional work and materials, as well as costly schedule delays. Beyond accuracy and precision, a detailer is expected to achieve perfection.