There is a cloud drawn around part of your duct run, and a little triangle next to it with a number in it.
Something in there changed. That is what the balloon is telling you, and that is most of what it is telling you.
This goes with how to read HVAC drawings on a commercial job and whose job it is to update the drawings.
The cloud and the delta
The cloud is the shape around the area that changed. It does not say what changed or why. It says look here.
The triangle is the delta, and the number in it is the one that matters.
Word of the day: delta. The triangle with a number in it. That number is an issuance of sheets, usually a bulletin or proposal request. So the delta is not telling you what changed. It is telling you which release the change came in with.
The deltas are listed on the right side of the sheet, with the rest of them, by date of release.
That list is the part people skip, and it is the useful part. It tells you how many times that sheet has been revised, when, and roughly what for. A sheet with six deltas on it has been fought over. That is worth knowing before you build off it.
So the read is: find the cloud, get the delta number, go to the list on the right, find that number, see the date. Now you know whether the change is older than the last time you looked at this sheet or newer.
The sheet says it is current
It does, and the architect put that there, and it was true the day it was issued.
What the stamp cannot cover is anything that has happened since. An RFI answer that came back last week. A change directive from the owner. Those are real changes to your work and they exist before anybody redraws a sheet.
A current sheet is current as of a date, not as of today.
A delta is an issuance, not an edit
This is the distinction that makes the rest of it make sense.
A delta is an issuance of sheets. Usually a bulletin. A PR, a proposal request, is the same idea under a different name.
So the delta number is the package, not the pencil stroke. When you find delta 4 on your sheet, delta 4 is a release that went out on a date carrying a batch of changes, and the cloud is showing you which part of your sheet that release touched.
Which means RFI answers are not on there
An architect does not typically put a delta mark on an RFI.
An RFI answer is direction. It governs your work the day it lands, and no drawing shows it.
The drawings catch up later. On a lot of jobs the architect issues an updated conformance set on a cycle, and every RFI that came back since the last one gets wrapped into it. On mine that was monthly. Doing it at regular intervals is a great deal easier than saving it all for the end of the project, which is the alternative and it is worse. Most of the time it will be never or the end of the project. Which means it is critical that the drawings are update with info as it is released.
So there is a window, and on a monthly cycle it can be most of a month, where an answer exists and no sheet shows it.
That is the real reason a stamp saying current is not the same as current. Nothing on the drawing is wrong. The drawing is just not where the newest direction lives yet.
Which is why “check the drawings” is not a complete answer, and why the people who know what came back on the last RFI is worth standing next to.
So somebody draws it in by hand
That part is on the GC, and it is manual work. An RFI answer gets put onto the sheet one of a couple of ways.
- A snip or clip of the answer, pasted over that spot on the sheet.
- An excerpt linked to a text box, with a cloud drawn around it by the GC.
And the RFI number goes on the sheet as a link to the change. That is the piece that makes it referenceable, and the GC has to be the one to put it there.
Which means not every cloud on your set came from the architect.
The architect’s clouds arrive with a delta number, because they came in with an issuance. A cloud the GC drew carries a different number. An RFI number, or an ASI number, linking back to the document that says what happened.
Which number it is tells you where to go
This is the part worth carrying around. Not every number on a sheet points at the same place.
- A delta number sends you to the list on the right side. It came in with an issuance.
- An RFI number sends you to that RFI. Live direction, and it may not be in any issuance yet.
- An ASI number sends you to that ASI.
The sheet does not tell you what changed or why. The number does, by taking you to the document that does. A cloud without a number to chase is half an answer. If there is not a number, reference the delta number in the title block.
And this runs opposite to how it looks. A cloud carrying an RFI number instead of a delta is not less official. It is newer. An RFI answer is part of the contract documents the moment it comes back, so that hand marked cloud is live direction sitting on the sheet ahead of the issuance that will eventually absorb it.
So a change has three states you can actually see:
- Nothing on the sheet. The answer exists and nobody has marked it yet.
- A clip or a text box with a cloud, carrying an RFI or ASI number. The GC put it there. This is the newest information on that sheet.
- A cloud with a delta number. It made it into an issuance. Now it is drawn, not annotated.
State one is the one that hurts, and it is the reason to ask rather than only look.
The ASI
One more worth understanding, because it has an argument built into it.
An ASI has come to me as a new sheet. From there it gets handled like anything else. Overwrite the old one, paste over it, or insert the clips, and reference the ASI number with a link.
What makes it its own animal is why an architect reaches for one. He reaches for an ASI when he feels the thing is a clarification and does not generate a cost.
Usually it is a change. It is just subtle enough that somebody wants to argue about the dollars.
You are not the one having that argument and you should not try to be. But when your PM goes quiet and reads an ASI twice, that is what he is reading it for.
Who is supposed to tell you
Your own company. The sub’s management has to get the information down to the field.
Your foreman has access to the drawings on site. He still has to look at them. Access is not the same as having looked.
How fast that happens comes down to what the job runs on:
- Digital. Instant and easy. The update is there the moment it is posted.
- Paper. A day or two of delay, every time, built into the method.
Two days does not sound like much until you spend one of them fabricating.
Nothing is protecting you
I want to be straight about this because it would be easy to write a tidy checklist here and pretend it is a safety net.
There is no agency, no gate, no second set of eyes that catches anyone building off an old sheet. A sub is going to build off the information available to him. That is not carelessness, that is what work is.
The only real defense is speed. If something changed, the field needs to know about it fast, and fast is a choice a company makes in how it moves paper, not a virtue an individual can supply.
What you can do is small and it is not nothing. Look at the delta list before you start a run. Ask when the set on that table was last updated. Ask whether anything is outstanding.
Why your foreman is tense about this
Because when duct gets built off a superseded sheet, the sub eats it. Every time, as long as the GC did its job and got the current information out.
If the GC did not, then the offices argue and eventually settle. That argument is not yours and you should not spend a minute of your day on it.
It is worth knowing it exists, though, because it explains something you have probably seen. A foreman who seems unreasonable about which set you are working from is not being particular. He is standing between his company and a bill.
It is also why superseded sheets get kept instead of thrown out. They are the record of what changed from the original pricing, and somebody is going to need that.
The short version
- The cloud says look here. The delta says which issuance. Neither one tells you what changed.
- The delta list is in the title block (right edge of the page), by date of release. That is where the cloud becomes information.
- A delta is an issuance of sheets, usually a bulletin. A PR is the same idea.
- RFI answers do not get a delta. They are direction, and the drawings catch up on a conformance cycle, sometimes a month behind.
- A cloud carrying an RFI or ASI number instead of a delta was marked by the GC. That is not older information, it is the newest on the sheet.
- Chase the number. Delta goes to the list, RFI goes to the RFI, ASI goes to the ASI. The cloud alone is half an answer.
- A current sheet is current as of a date, not as of today.
- An ASI is usually a change dressed as a clarification. Not your argument, but now you know why the room gets quiet.
- Digital updates land instantly. Paper costs you a day or two. Every time.
- Nothing catches a man building off an old sheet. Speed is the only defense there is.
- Superseded sheets get kept because they are the record of what changed from the original pricing.