What NOT to show on structural drawings

[kbbandw]

Hi I have a question related to structural drawings and details and relates to non-structural items or items not specifically designed by structural engineer.

1) Should structural foundation detail show foundation drains? Typically this, in my opinion, should be shown on civil or arch drawings and not on structural.

2) Should structural foundation detail show insulation? Again, should not since it belongs on architectural dwgs.

3) Similarly any items such as roof insulation, flashing etc should NOT be shown on structural drawings.

The main question is: Is there an official reference (code document, CASE document, SEI document, DPIC document, etc) that lays it out in terms of what should NOT be shown on structural drawings from a liability and responsibility standpoint?

Your response and help is greatly appreciated

Thanks,

 

[Den32]

We show foundation drainage system and insulation and say "See Arch. Dwgs". For roofing, we show a finish line and say "Roofing Materials - See Arch. Dwgs".

 

[jike]

You will probably not find any "standard way" of doing it. I have seen drain tile on architectural, plumbing and structural drawings. It may also depend upon whether the project goes out in multiple packages or not.

My philosophy is if it affects the structural integrity, then I will generally show it. For instance, if drain tile is not installed it can cause an overload condition on a basement wall or retaining wall.

It also makes some sense to show perimeter insulation and drain tile on the foundation drawings, since it needs to be installed at the same time.

 

[ash060]

Most building codes describe what has to be shown on structural drawings as a minimum. My old boss used to say "beams, columns, footings, walls", but I think that can be a little light.

If it is not structural you do not have to show it, but sometimes having it on the plans will help with coordination.

I mean you could show everything on the plans from the rebar to the flashing, but I think that crowds a drawing. Also, with BIM out there it maybe that plans will start showing everything anyway, so showing it now may help everyone get used to it.

 

[msquared48]

1. If the foundation drain affects the structure, I show it.

2. If the insulation affects the slab or footing layout, postions of the structure, I would show it, only to show coordination with the Architectural requirements.

3. Insulation - hardly ever, but flashing, sometimes in critical areas, but always referring back to Architectural details.

There are mo formal guidelines that I know of - just professional preferences. Remember that showing coordination between the Architect and Structural Engineer is critical in the plans.

Mike McCann
MMC Engineering

 

[structuresguy]

I would agree with most of teh responses so far. I typically show items that either have an effect on the structural capacity (such as drains) or impact the construction sequence. Then I refer them to the appropriate designer (arch, civil, etc). Also, if you need a drain, say, behind a retaining wall, then if you don't show it, how will the civil know to provide?

I also show waterproofing under foundations, elevator pits, etc. And insulation under walk in coolers and freezers, if needed. I typically don't show roof insulation in my details, unless there is some specific reason, say a clear height of a roof top unit frame over the finished roof line.

 

[MiketheEngineer]

If you need it for structural purposes - show it. While more is usually better than less - you will/might be responsibe for it.....

 

[JAE]

Foundation Drains - we show it for the same reasons as above - it significantly affects structural behavior and I want to have control over that.

For the others (flashing, insulation, etc) we might show the presence of it for context, but we would not note it.

My view of structural drawings:
1. The most important part of any structural drawing is the notes. Think of the drawings NOT as linework supported by notes, but by notes that are supported and clarified by linework.

2. You should note (specify) all items that are structural elements and all items that are crucial to the strength and stability to those structural elements.

 

[BigH]

JAE - my star for you! . All too many times I see structural drawings with no notes or so little . . . Maybe it was overkill when I learned from our mentor - but nothing on a drawing was left to assumption or presumption.

 

[jrwhite2013]

One thing to keep in mind is that you are creating drawings for the fabricator/detailer not necessarily for the builder. What ever the fabricator needs to know should be on the drawings. Also, keep in mind that you are not just putting stuff on the drawings that affect the structure as it is designed currently, but also for when something changes and you need to redesign. Drain openings are important to see on slab plans because you will likely want to show the slab slope lines terminating at the drain opening.

- jw

 

[BAretired]

JAE,

I agree that notes on structural drawings are important. While I do not quarrel with anything you have said, I am not so sure that notes necessarily take precedence over drawings. Rather than leaving the matter to be decided by a bunch of lawyers, perhaps it would be wise to review both the notes and the drawings. A deficiency in either is likely to be problematic for the engineer producing the documents if the matter ever gets to court.

Best regards,

BA

 

[JAE]

BAretired,
I appreciate your comment. Maybe to clarify what I meant.

For "notes" I meant all the notes - the general notes as well as all the leader notes on the details.

I wasn't suggesting that in a legal sense, with conflicts and such on drawings, that the notes take precedence.

What I was suggesting, was that if the engineer focuses more on the notes in each detail, the design documents will be of a better quality.

I've seen so many times when details are drawn indicating required work under the contract, but few or no associated notes calling out the required welds, sizes of plates, angles, etc.

So the linework should support the notes as opposed to the notes supporting the linework. If that concept is used as details are developed, then the details will be of a much more complete and comprehensive quality.

A similar analogy to this is the report brought out by the NBS years ago in their study of the Hyatt Regency walkway collapse. Edward Phrang, who went around the country speaking on this subject, summarized their findings by suggesting that engineers should think about structures as a series of connections linked together by beams and columns, rather than thinking of them as a series of beams and columns which happen to be connected together. In other words, "It's the connections, stupid."

It's simply a question of focus as you design. So in my view - a little more emphasis on the notes is a good thing.

 

[csd72]

Generally if it effects your structure then you should note your assumptions about it on your drawings.

e.g. if you have assumed that the backfill behind a retaining wall will be drained then note"drain to civil engineers details" or similar.

 

[archeng59]

Notes are absolutely important, in my opinion. In addition to general notes and leader notes, dimensions are important. Not all dimensions need to be shown on the structural drawings, especially if they occur on the architectural drawings. Dimensions specific to the structural components. This might sound like a no-brainer, but I worked with a couple of older engineers who prepared drawings that did not include dimensions and notes for some structural components and assemblies. They wanted to show a generic detail, and plans, without much information on them. During construction, the contractor was calling alot to find out what the engineer intended. After I started my own firm, I added alot of notes and dimensions on the drawings. I have few questions from contractors. They won't know how to build it without adequate info. They won't build it the way you want it built without adequate info.

 

[JAE]

This brings up a topic that probably should be a new thread - but I've seen a trend in recent years where engineers are more and more delegating design tasks to the contractor.

archeng59 - your older engineer example is where an engineer takes it to a ridiculous extreme, in my opinion.

It's sort of like a structural engineer, taking a fee to design a structure, and then simply putting a big note in a box on their one sheet saying: "the contractor is responsible for finding a consulting engineer to design the structure to meet all applicable codes and to coordinate with the architectural drawings herein."

I dislike this sort of delegation as it seems to me we are delegating away our role in the projects and thus delegating away our whole purpose in being in the business of engineering.

(rant over - thanks for your patience)