Renovation Steel Takeoff: New vs Existing Members
A renovation steel takeoff starts by splitting every member into new steel you supply and existing steel you only touch. Callouts marked EX, (E), EXIST or EXISTING are already in the building. Counting them as new inflates your bid, and pricing the work done to them as zero sinks your margin. Get that split right and the rest is a normal takeoff.
Renovation and tenant improvement (TI) drawings mix the two on the same sheet, often in the same detail. Here's how to read them, what to price and where the risk sits.
Why do renovation drawings break a normal steel takeoff?
A new-build structural set shows the steel you're going to make. A renovation set shows the building as it is, plus what changes. That creates problems a normal takeoff process doesn't expect:
- Existing members are drawn and labeled like new ones. A
W16X26callout and an(E) W16X26callout look almost identical at plan scale. - Demolition and new work share sheets. Some steel comes out, some stays, some gets added.
- Reinforcement shows up as small details. A plate welded to an existing beam's bottom flange might be the main scope of the job, but it appears as a detail bubble, not a plan callout.
- Dimensions are uncertain. Notes like "field verify" or "V.I.F." (verify in field) mean the drawing's lengths are a guess.
- Old shapes don't match today's catalog. A beam from the 1950s may be a size no mill rolls anymore.
Every one of these turns into a pricing error if you count the drawing the way you'd count new construction. Our post on common steel takeoff mistakes covers more general traps; renovation adds its own.
How do you read EX, (E), EXIST and N notation?
Engineers mark existing members in several ways. Learn to spot all of them, and check the general notes and legend for the convention this engineer uses.
| Notation | What it usually means | Example |
|---|---|---|
| (E) | Existing | (E) W12X26 |
| EX or EX- | Existing | EX-W18X45, EX. W16X26 |
| EXIST, EXISTG, EXG, EXTG | Existing | EXIST W8X10 |
| EXISTING | Existing | EXISTING W21X49 |
| (N) or NEW | New | (N) W10X22 |
| (R) or REMOVE | Remove / demolish | (R) W8X15 |
| (D) or DEMO | Demolish | Shown dashed on demo plan |
| Dashed or screened line | Usually existing to remain | Line type defined in legend |
| Bold or solid line | Usually new work | Line type defined in legend |
Our steel abbreviations and drawing symbols guide has a fuller list.
A few things to watch:
- Not every engineer marks new steel. Many mark only existing, so anything without a prefix is new by default. Others mark only new. Read the legend.
- Line types matter. Existing steel is often drawn dashed or screened. On a dense sheet at small scale, that difference is easy to miss.
- Prefixes can be separated from the size. "EX." may sit on one line and "W16X26" right next to it. Read the whole label, not just the size.
- Demo plans and new plans may both show the same member. Count it once, in the right bucket.
For a broader refresher on sheet types and conventions, see how to read structural drawings.
If you're tired of separating existing from new by hand, SteelFlo boxes every steel callout on every sheet, and you confirm or reject each one in review, so existing members you aren't supplying come out of the count without disappearing from the drawing. Upload a renovation set and check it against your own read; the first 3 takeoffs are free.
New vs existing: what do you supply and what do you only touch?
Once each member is in its bucket, figure out what you're actually doing to it. Existing steel isn't free; it's just priced differently.
| Category | Material | Shop labor | Field labor | Typical pricing |
|---|---|---|---|---|
| New member | Yes, full weight | Full fab | Erect | Normal per-lb or per-piece |
| Existing to remain, untouched | No | No | No | Not in the bid |
| Existing, reinforced | Plates, angles only | Fab the add-on pieces | Field weld or bolt in place | Per-piece plus field labor |
| Existing, new connection | New clips or plates | Fab the clips | Field drill, bolt or weld | Per-connection |
| Existing, removed | No | No | Cut, rig and haul (if in scope) | Demo labor, often excluded |
| Existing, relocated | No new steel | Possibly modify | Remove and reinstall | Field labor heavy |
The middle rows are where money gets lost. A TI job might have 3 tons of new steel and 40 reinforcement details on existing beams. The reinforcement weighs almost nothing, but each one is a field weld in an occupied building, often overhead, maybe with fire watch.
What about historic shapes and field-verify dimensions?
Historic shapes
Buildings from before the 1970s or so often have sections that aren't in today's catalog. A 1950s beam might be called a "12 WF 27," which is how wide flange shapes used to be labeled, or a size dropped decades ago. Pre-1900 buildings can even have wrought iron.
Where to look:
- AISC Design Guide 15: Rehabilitation and Retrofit (second edition) includes reference dimensions and properties for discontinued steel and wrought iron shapes going back to the 1870s, plus a history of ASTM material specs. AISC members can get it free.
- The AISC Shapes Database covers current shapes. AISC also maintains historic shape data through its shapes database pages.
- Our shapes reference pages cover current sections for quick weight lookups.
For estimating, the main reasons this matters:
- Weight. If you're removing or relocating old steel, you need a weight for rigging and scrap. A historic shape may weigh a bit more or less than the closest modern section.
- Fit-up. A new member connecting to an old one needs to match the old flange width and depth. Get those from field measurement, not from today's catalog.
- Weldability. Old steel may not be as weldable as modern A992. The engineer may require testing before welding, which affects schedule and price.
Field-verify dimensions
"Field verify" means the engineer drew it from old drawings or a quick survey and isn't sure. For your bid:
- Price a site visit or a measurement trip before shop drawings. Note it in your scope.
- Carry length allowance on new members that frame into existing steel. A beam might be 1" to 3" different than drawn.
- Fabricate in stages if you can. Field-measure, then fabricate the connecting pieces.
- State the assumption. "Bid based on dimensions shown; field verification by others" or "includes one field measurement trip."
The AISC Code of Standard Practice has a section on existing structures, and AISC's toolbox talk on Section 1.9 summarizes what it says about who provides information on the existing building. Read the current Code for exact language before relying on it in a scope letter.
How do you price reinforcing existing members: plates, angles and welding?
Reinforcement is the most common renovation steel scope after new framing, and it's where shops most often underprice.
Common reinforcement details
- Bottom flange cover plate: a plate welded to the underside of an existing beam's bottom flange. Example: PL 1/2 x 6 x 14'-0" welded to an (E) W16X26.
- Web doubler plate: plate welded to the web, usually at connections.
- WT or angle added to the flange: for more capacity.
- New stiffeners: plates at bearing points or under new concentrated loads.
- New intermediate beams framing between existing ones, with new clip angles bolted or welded to the old steel.
What to count for each
| Item | What to take off | Watch for |
|---|---|---|
| Reinforcing plate | Plate size and length, quantity per beam | Holes for clamping, field fit |
| Fillet welds | Weld size and length per detail | Intermittent vs continuous, overhead position |
| Surface prep | Area to clean of paint or fireproofing | Lead paint, fireproofing removal often by others |
| Shoring | Who shores during the work | Almost always excluded or by others |
| Fire watch | Required during hot work in occupied buildings | Usually needed; check the spec |
| Fireproofing repair | Restore after welding | Often by others |
Field welding cost. Field welding is far slower than shop welding: setup, access, overhead positions, wind protection, fire watch and inspection all add time. A 14 ft cover plate with two continuous 1/4" fillet welds is 28 ft of weld, all overhead, plus tacking and fit-up. Price it with field welding units, not shop units. Our welding cost estimating guide walks through weld volume and labor math.
AWS D1.1 includes provisions for strengthening and repairing existing structures, and the project spec may reference them. The AWS standards catalog lists the current editions.
Worked example
Scope: reinforce 12 existing W16X26 floor beams with a PL 1/2 x 6 x 14'-0" bottom cover plate each, continuous 1/4" fillet both sides.
- Plate weight: 6" wide x 1/2" thick = 3 sq in per foot of length. At 3.4 lb per square inch per foot, that's 10.2 lb/ft. Times 14 ft is about 143 lb each, or about 1,714 lb for 12.
- Field weld: 2 x 14 ft = 28 ft per beam, 336 ft total, overhead.
- Field labor: surface prep, fit and clamp, weld, inspect, touch up.
The material is less than a ton. The field labor on 336 ft of overhead fillet weld in an occupied building is what you're really pricing.
What should renovation scope letters include and exclude?
Spell out the new-vs-existing line in writing. Sample language to adapt:
Includes:
- New structural steel members shown as new on the structural drawings.
- Reinforcing plates and angles at existing members as detailed.
- Field welding of reinforcement as detailed.
- One field measurement trip prior to shop drawings.
Excludes:
- Existing steel shown to remain.
- Demolition and removal of existing steel unless listed.
- Shoring and temporary support.
- Fireproofing removal and repair.
- Lead paint and hazardous material abatement.
- Testing of existing steel for weldability.
- Changes caused by field conditions differing from the drawings.
Our bid scope letter guide has more exclusion templates.
Frequently Asked Questions
What does (E) mean on structural drawings?
(E) means existing. A member labeled (E) W12X26 is already in the building and is usually not supplied by the fabricator. Check the drawing legend, because some engineers also use EX, EXIST or line types to show existing work.
Should existing steel be included in a takeoff?
Existing steel to remain shouldn't be in your material count. But any work done to it, such as reinforcing plates, new connections, removal or relocation, should be priced as its own line. Leaving existing members in the count inflates the bid.
How do I find the weight of a historic steel beam?
Use AISC Design Guide 15, which includes reference data for discontinued steel and wrought iron shapes, or AISC's historic shapes data. Confirm critical dimensions by field measurement. Today's catalog may not have an exact match.
Why is renovation steel more expensive per ton?
Because most of the cost is field labor on small pieces: field welding, surface prep, access, fire watch and working around occupants. A reinforcement scope can be under a ton of steel and still carry a lot of labor hours.
What does "field verify" mean on a steel drawing?
It means the dimension or condition shown isn't confirmed and has to be measured on site. Price a measurement trip, carry length allowances and state in your bid who's responsible for verification.
Bottom line
On renovation work, the takeoff is only as good as your split between new and existing. Count new members, price the work done to existing ones as its own scope, and write the line down in your bid. In SteelFlo every callout stays boxed on the drawing, so you can confirm the new-versus-existing split sheet by sheet before you price.