Knowledge centerArchitectural Drawing Abbreviations
Drawings are dense, so almost everything gets abbreviated. Most are obvious once you have seen them a few times; a handful are genuinely ambiguous and worth pinning down.
The ones you will see constantly
- RCP — reflected ceiling plan
- AFF — above finished floor
- FF — finished floor
- FFL — finished floor level
- EL or ELEV — elevation (either the drawing type or a height)
- TYP — typical, meaning it repeats and is only annotated once
- UON — unless otherwise noted
- NIC — not in contract
- EXIST or EX — existing
- DIM — dimension
- CLG — ceiling
- CL — centerline
- OC — on center
- GWB — gypsum wall board
The ambiguous ones
EL is the worst offender: it means both “elevation drawing” and “elevation above datum”, and which one is meant depends entirely on context. FL can be floor or flow line. CL is centerline, but appears as a symbol as often as letters.
Why abbreviations matter on an as-built
When we document an existing building, we produce drawings to your office standard — including your abbreviation conventions. The rest of the vocabulary is in the knowledge center. A survey drawn in someone else’s shorthand costs your team time to read, which defeats the point of buying it.
Levels, dimensions and setting out
| Short | Meaning | Worth knowing |
|---|---|---|
| AFF | Above finished floor | Measured from the finished surface, not the slab. On a renovation the finish may be changing. |
| FFL | Finished floor level | An absolute height, usually tied to a project datum. |
| TOS / TOC | Top of steel, top of concrete | Structural references. Neither is the same as the finished floor. |
| CL | Centerline | Appears as a symbol at least as often as letters. |
| OC | On center | Spacing measured centre to centre, not clear between. |
| CLR | Clear | The opposite: the usable dimension between faces. |
| DIM | Dimension | Often paired with a note that it is verified on site. |
Materials, services and status
| Short | Meaning |
|---|---|
| GWB | Gypsum wall board |
| CMU | Concrete masonry unit |
| ACT | Acoustical ceiling tile |
| AHU / VAV / FCU | Air handling unit, variable air volume box, fan coil unit |
| MEP | Mechanical, electrical, plumbing |
| EXIST / EX | Existing |
| DEMO | To be demolished |
| NIC | Not in contract. Present in the building, provided by somebody else. |
| UON | Unless otherwise noted |
| TYP | Typical. Annotated once, applying wherever the condition repeats. |
| VIF | Verify in field. On a set with no survey behind it, this appears everywhere. |
VIF is the one worth pausing on. A drawing set carrying it on every critical dimension is telling you that nobody measured the building. That is precisely the gap an existing conditions survey closes.
Same letters, different meaning
- EL is the worst offender. It means both an elevation drawing and an elevation above datum, and only context separates them. On our deliverables we write ELEV for the drawing and give heights a datum reference.
- FL can be floor or flow line. In a drainage context it is nearly always the latter.
- CT can be ceramic tile or cable tray, which are rarely confused in a bathroom and easily confused in a corridor.
- RD can be roof drain or road. Discipline prefix usually resolves it.
- SF can be square feet or storefront, and on a leasing plan both are plausible.
There is no single standard for any of this. Most offices keep a legend sheet, and that is exactly why we ask for yours before drafting starts: a survey drawn in someone else’s shorthand costs your team time to read, which defeats the point of buying it.
Which sheet carries which information is set out in drawing types. More vocabulary sits in the knowledge center.
Frequently asked questions
Is there a single standard?
No. There are conventions, and most offices keep a legend sheet. That is exactly why we ask for yours before drafting.
What does AFF measure from?
The finished floor surface, not the structural slab. On a renovation the difference matters, because the finish may be changing.
What does VIF mean, and why does it matter?
Verify in field. It marks a dimension the drawing does not stand behind. A set carrying it on every critical dimension is telling you the building was never measured.
Will you draw to our abbreviation list?
Yes. Send the legend sheet with the brief and the deliverable arrives in your conventions. Where no written standard exists, we deliver ours as a document so the next consultant has something to follow.
Documenting a building?
Tell us what you need measured.