A DD-to-CD change narrative is a written summary of what changed between the design development (DD) set and the construction documents (CD) set, the second and third of the three design phases after schematic design (SD): added, removed, or revised scope, organized by discipline and building area, with the sheets affected and the reason for each change. Estimators use it to reconcile pricing, owners use it to confirm the project still matches what they approved, and contractors use it to understand what moved before bidding. It is built by comparing the two sets and explaining the differences—not by re-describing the whole project.
Who needs the narrative and when
- Owner and developer: to confirm the CD set is the DD set they approved, plus agreed changes—and to catch scope that drifted in without a decision.
- Cost estimator: to update the DD estimate by delta rather than re-quantifying the building; a good narrative cuts reconciliation time dramatically.
- Contractor and preconstruction team: to focus constructability review on what changed, and to price the change rather than the whole set.
- Design team: as the record of decisions between milestones, which pays for itself at the first "why did this change?" meeting.
The same method applies to CD-to-permit, permit-to-bid, and addendum narratives; DD-to-CD is simply the one with the most change.
What goes in it
Keep the structure boring so readers can find things. A workable outline:
- Header: project, the two sets compared (issue names and dates), who prepared the narrative, date.
- Summary: five to ten lines on the biggest changes and their drivers (owner request, code comment, coordination, cost, consultant input).
- Changes by discipline: architectural, structural, mechanical, electrical, plumbing, fire protection, civil, landscape, interiors. Within each, group by building area or system.
- For each change: what changed, the sheets affected in both sets, why it changed, and any cost or schedule implication the design team is aware of. One or two sentences each.
- Unchanged scope worth confirming: items the reader might expect to have changed but did not, such as a program area that was discussed and kept.
- Open items: decisions still pending that will produce further change.
Every entry needs a sheet reference on both sides. "Revised lobby ceiling" is a reminder; "Lobby ceiling revised from GWB at 12'-0" (DD A2.11) to wood slat at 11'-6" (CD A2.11, A7.03)" is a narrative entry.
How to build it from two drawing sets
- Align the sheet lists. Match each CD sheet to its DD counterpart; list sheets that were added, deleted, or renumbered. Renumbering alone hides a surprising amount of change.
- Compare sheet by sheet. Overlay or side-by-side each pair, discipline by discipline. Note every difference, even ones that look cosmetic; decide later which are narrative-worthy.
- Check the schedules and specifications. Plan changes are visible; schedule changes are not. Compare door, finish, equipment, and structural schedules line by line, and compare the specification tables of contents.
- Attribute each change to a driver. Pull from meeting minutes, owner directives, code comments, and consultant coordination logs. A change without a driver is the one the owner will question.
- Group and write. Cluster the raw differences into changes a reader cares about, write the entries, and have each discipline lead confirm their section.
- Route it with the set. The narrative belongs in the same transmittal as the CD issue, not a week later.
Check the CD set before it goes out
Find conflicts in the construction documents early. Groundbook flags potential conflicts with links to the source sheets.
Common mistakes
- Describing the building instead of the change. The reader has the set; they need the delta.
- Missing schedule and spec changes. The most expensive changes are often a line in a schedule.
- No sheet references. Without them the estimator has to find the change again.
- No driver. "Revised per coordination" invites the question "coordination with what?"
- Written from memory. The narrative should come from the comparison, not from what the team recalls changing.
How drawing version comparison helps
Step 2 above is the slow part, and it is the part that gets skipped under deadline. Groundbook AI's drawing version comparison (available to beta users on request) takes the previous and current PDF sets, organizes the differences, and helps architects and engineers draft a source-linked change narrative between milestones, while contractors can focus constructability review on what actually moved. It does not replace estimating or the professional review of the change—it makes sure the comparison is complete before anyone writes.