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Slab on grade drawing preferences
2

Slab on grade drawing preferences

Slab on grade drawing preferences

(OP)
I have seen drawings with floor drains indicated on the slab-on-grade/foundation plans (including ones at that do not require the slab to be sloped),and I have seen drawings with no floor drains with a note referencing to see plumbing. What all would be the reasons to show approximate floor drain locations when a slab slope to them is not required? I would think to check for footing interferences with plumbing.

RE: Slab on grade drawing preferences

Pros:
-makes sure the GC doesn't cut the concrete sub loose on the slab before the plumber has a chance to come out.
-forces you to look at the plumbing drawings and coordinate

Cons:
-more drafting with a chance of the plumbing designer making a change and not telling you

RE: Slab on grade drawing preferences

(OP)
Agree with the potential for a change and them not telling you. For this chance, I think the best I can do is to also provide a CYA note to see and coordinate locations shown with the plumbing drawings.

I agree with the sub pouring concrete and not being aware of the drains and then having another issue.

But I think I would also want to show, before I stamp a drawing, whatever drains that I am aware of that are close to columns. This can suggest a pipe below conflicting with a footing or anchor pullout cone. And if more drains lines are added later without my knowledge, then I have some basis shown that I stamped. But I don’t think I have ever gone as far as dashing in the plumbing line locations that I designed for.

RE: Slab on grade drawing preferences

Can anyone of you share a SOG drawing showing drain locations?
I have never seen one.
Just wanna see out of curiosity.

RE: Slab on grade drawing preferences

I haven't done one since my last firm, so I don't access to the drawings. Pretty simple though. It's a circle with a note or keynote that says something along the lines of "FLOOR DRAIN, REFER TO PLUMBING AND ARCHITECTURAL DRAWINGS"

RE: Slab on grade drawing preferences

The concrete contractor is the last line of defense to make sure that any required drains are present before the concrete starts flowing. Its easier to stop or move to another pour than it is to sawcut a pour.

RE: Slab on grade drawing preferences

What happened to contractors who actually read and understood the plans? It really seems that now days we are having to add more and more stuff that is shown elsewhere in the "Contract drawings". Our drawing isn't the only one they should be building off of, the contractor should be reading all the drawings and not relying on each discipline to add content from other disciplines to their drawings.

I do agree that you as the structural engineer should know where these drawings are and make sure they are coordinated, however you should not need to show it on your drawings.

RE: Slab on grade drawing preferences

(OP)
Contractor's can't be relied on, at least not in my area and projects I work on. And then it ends up coming to me as an RFI to approve them cutting up the slab.

RE: Slab on grade drawing preferences

I completely agree with you that they can't be relied upon, however we are expanding the problem by catering to them by increasingly adding more and more to our drawings/scope without being justly compensated for the extra work due to their inability to coordinate plans between disciplines. Where do we as engineers draw the line, what kind of liability are we taking on by adding other disciplines stuff to our drawings, it seems like a no win scenario for engineers.

RE: Slab on grade drawing preferences

I do industrial facility stuff and literally everything is on the drawings, at least as a greyed out representation. The world where you get to just design your stuff and let the trades work out the co-ordination sounds magical.

RE: Slab on grade drawing preferences

That world is magical now days for sure, but there was a time where contractors could coordinate when building. There are still a few great contractors around (older guys) who do an amazing job with this, but far more that don't seem to be able or willing to think beyond one thing at a time. Like I said, we engineers allowed the industry to get to this point by being too catering to others not "doing their job", not much we can do to fix it now. With Revit, I believe it's a matter of time before contractors require the models to be able to build things and will want LOD 500+.

RE: Slab on grade drawing preferences

My 2 cents, I'm all for more work to do on the design side, coordination and detailing included. It seems like a good way for clients to see value play out (minimizing problems during construction), because they certainly don't often see the building performance (e.g. L/240 vs L/360). Easily recognized value is where the money is at.

* edit: actual monetary compensation required

RE: Slab on grade drawing preferences

I got an RFI from a contractor asking for a layout of all the housekeeping pads in the mechanical room because “it would be a lot easier” if he didn’t have to do it himself.

RE: Slab on grade drawing preferences

For the owner to see the value added, that would require they have and see the problems on other projects, which in most cases they are unaware of. I'm not sure if owners see all the RFI's, etc. that are generated because the contractor wants someone else to do his job for him. JLNJ hit the nail on the head there, I too am seeing simple looking RFI's like you mention that are a waste of my time if not justly compensated for their "not wanting to do their job".

RE: Slab on grade drawing preferences

I have no issues coordinating base files with civil, mechanical, etc., whoever.... And I try wholeheartedly to do so from the beginning. The problem is that if you are working with someone who is less than stellar, when push comes to shove and they are scrambling to make changes to their drawings last minute, sometimes things get lost in translation and there can be inconsistencies across the disciplines on the contract drawings. I guess that's just the nature of our work though.

I normally like to have input in the location of the drains since it can have an affect on your jointing plan. By treating this as "someone else's problem" and expecting the mechanical to show it correctly and the contractor to coordinate it is asking for problems in my opinion.

Here is one example of a walkway ramp leading up to a bridge with some drain inlets. It's simple enough. As long as the mechanical/civil sends you their base file, you can adjust your jointing as needed (or adjust the drain locations) and give general trim bar reinforcing details.

RE: Slab on grade drawing preferences

In your official response to the RFI inform the contractor that the information is contained in the contract documents...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Slab on grade drawing preferences

STrctPono - I agree, we have to coordinate and yes things can get missed when last minute, which this year seems to be common with many disciplines I have seen with everyone being so busy.

RE: Slab on grade drawing preferences

(OP)
I have said before that I have to make drawings that a monkey would be able to build from them. I look at it now like this, do I want to deal with it now or have the bigger headache during CA? And sometimes the fixes just aren't going to be as strong or long lasting as what was originally intended. Like a slab that has been cut up to install utilities in a building with heavy wheel traffic that will now have a lot of doweled joints at all the new sawcuts.

And some on here may say "make them tear it all out and start over" but that doesn't usually work for me. The contractor gets the owner on his side and wants a fix to keep the project moving, and then the owner expects me state why the fix won't work if I am gong to require a complete replacement. Add in the salesmen that run a lot of AE companies that want to keep the owners happy, and it starts to feel like it's me against the contractor, owner, and sometimes the people I work with.

RE: Slab on grade drawing preferences

dik - so funny enough, I basically just said that in an RFI response; I referenced them to the detail they were asking for, that was in the CD's.

RE: Slab on grade drawing preferences

I would show the drains, but not locate them. Caveat that I'm in industrial.

One time I had a contractor see that there were going to be penetrations for electrical in the SOG, pour the slab and then core holes for the conduit after. So even with your best efforts they will find a way to mess it up.

RE: Slab on grade drawing preferences

(OP)
Regarding coordination, that kind of relates to what I was saying about wanting to see where things are that could affect my structure at that instant in time when I stamp a drawing. If another discipline changes things at the last minute after I stamped my drawing, then at least I have a record of where they were when I stamped the structural.

I have actually also shown equipment pad locations when they are the type that are cast on top of the typical slab and have epoxy dowels connecting the slab to the pad. I don't like control joints going under those so I show them schematically and reference mech for actual locations.

RE: Slab on grade drawing preferences

Quote (haynewp)

Regarding coordination, that kind of relates to what I was saying about wanting to see where things are that could affect my structure at that instant in time when I stamp a drawing. If another discipline changes things at the last minute after I stamped my drawing, then at least I have a record of where they were when I stamped the structural.

I have actually also shown equipment pad locations when they are the type that are cast on top of the typical slab and have epoxy dowels connecting the slab to the pad. I don't like control joints going under those so I show them schematically and reference mech for actual locations.

This is the same approach I use. Unfortunately, being correct when the finger pointing starts is useless in the end. Because even if you did everything in your power to show the latest coordination model, if the mechanical changes 1 hour before documents are due, in the end guess who is going to have to update their plans? And guess who is going to look bad in front of the owner and contractor and who appears to be in the wrong? Legally you might be ok... This is why I understand Aesur's stance on the matter. If I know and trust the other engineering disciplines, then I show everything (even if only schematic outlines). If the other engineering disciplines are new to me and I don't know their worth, I am much more wary about cross-discipline items that I show on the plans.

RE: Slab on grade drawing preferences

(OP)
I am kind of selfish in that I put my PE license before anything else and have gotten a little bitter over 25 years. So if there is any chance that the structural design can be affected by someone else after I stamp my drawings, then I want a record of what I was willing to sign. If drains show up beside columns with plumbing lines that interfere with anchors after I issue a set, then I want to show what I knew of at the time I issued my stamped set.

RE: Slab on grade drawing preferences

As a contractor I'll say that I generally prefer plans that make reference to other DWGs or CDs but don't particularize it beyond that (e.g. locations or layouts). In the case of the OP, if the SOG has plumbing / electrical / whatever I would vastly prefer a note with a leader saying something to the effect of "refer to mechanical for plumbing locations to avoid interference with concreted elements" coupled with another one saying something to the effect of "slope surface to area drains per CDs" or what have you. It's absolutely not necessary but it is a nice reminder for me in case I forget (appreciate the help!), and it also eliminates the inevitable conflicts. When multiple engineers start to put other engineer's work on their DWGs things just have a tendency...to get messed up and I usually have conflicting sets of DWGs (architectural, mechanical, structural, etc) and chasing that down can an endless loop of "ask this dude"

On another note, there is some contractor bashing in this thread and I am sure some of it much deserved. But from the other perspective I have spent the better part of a day reviewing stamped DWGs that a first year engineering student would have known would not be acceptable (no design loads, impossible connections, conflicting schedule items, incorrect weld symbols, specifying non-existent components and specifying particular welds on these non-existent things, etc).

I know construction has become more of a ME sport more so than a team sport over the years. But if we can, lets try and be the people that bring it back to what it once was. We are all in this together!

CWB (W47.1) Div 1 Fabricator
Temporary Works Design
https://www.enable-inc.com/

RE: Slab on grade drawing preferences

Words to live by, Enable.

BA

RE: Slab on grade drawing preferences

Thanks... saved and passed on.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Slab on grade drawing preferences

(OP)
To Enable’s point, some engineers now are equally as bad.

RE: Slab on grade drawing preferences

That may be the best detail I've ever seen...

RE: Slab on grade drawing preferences

That's why I saved it... now to find a good use for it.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

RE: Slab on grade drawing preferences

(OP)
Thanks to all for the input.

RE: Slab on grade drawing preferences

I often work in a world where we are hired by Contractors to value engineer other designs. Whether it be a full redesign or a partial redesign we are usually about 95% successful in getting our design through. I'm not talking about "we can remove 10% of your rebar" type unscrupulous work. This is where we realize the original designer grossly oversized the foundations because they didn't know how to run the seismic or botched the framing plan because they chose the wrong members. Most of these Engineers have no right designing the structures that they are designing. Not only is the overall design bad but the detailing is bad too. I think most of the issues arise when Engineers try to take on new work outside of their comfort zone and don't know the standard of practice in that industry. So to Enable's point, there are plenty of bad Engineering designs as well.

Pmtottawa: Great detail!

RE: Slab on grade drawing preferences

I wanted to jump back into this thread to agree that there are many "bad engineering designs" out there as others have said. I tend to see this mostly in over sizing members and lack of lateral designs.

I however also wanted to point out that many times engineering project managers and their engineering "monkeys" will over design members by grouping the members to save time and budget, ie designing a few worst case lintels and using everywhere, same goes for beams, footings, etc.. When a contractor asks for money to "VE" something those fees can be easily hidden in the loans (and most times VE will actually save money overall) and therefore the owner doesn't think much about it; however if the engineer was to raise their fees up front to design every member to provide the most cost efficient design the owner complains because the design fees tend to come directly from their own pockets as they typically cannot raise money for the project until the design and estimates are completed. It is unfortunate that this is the way the market works, however I don't see it changing anytime soon. Many engineers tend to work directly with architects, who too are competing for the project and therefore the lower their fee the higher the chances of getting the project, therefore their is no incentive to provide Value Engineering in the original design budget. This is why it's important to build relationships with developers and contractors, the ones who actually see your worth and how you can save them money on the project, even though your design fee may be higher than others.

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