A design development checklist for multifamily buildings
What a multifamily DD set holds, sheet by sheet and decision by decision, and the short list of questions that must be closed before construction documents begin.
What design development is for
Design development is the phase that turns an approved scheme into a building with real assemblies. The American Institute of Architects' standard owner agreement, B101, describes the DD documents as plans, sections, elevations, typical construction details and diagrammatic layouts of the building systems, together with outline specifications that name the major materials and systems and set their general quality levels (AIA Contract Documents, B101-2017 overview). The phase is meant to fix the size and character of the project before the detail of construction documents begins.
On a multifamily building that means settling the decisions every enlarged plan, detail and schedule in CDs will repeat dozens of times: the wall types, the unit layouts, the core, the floor-to-floor heights and the routes of the building systems. A decision left open at the end of DD is redrawn on every sheet it touches in CDs.
DD milestones and percentages
Many offices issue DD in steps named by percent, such as a 50% DD set for coordination and a 100% DD set for owner approval and pricing. The percentages are labels each office and owner agree on; no code or standard form defines what 50% or 100% DD contains. The checklist below works for either step if each item is marked as drawn, coordinated or open.
The checklist
General and code
| Item | What the DD set shows | Closed when |
|---|---|---|
| Code analysis | occupancy, construction type, allowable height and area, sprinkler system type, separations | the construction type and sprinkler standard are fixed |
| Fire separation plan | rated walls, floors, shafts and corridors on each level | ratings match the wall and floor types |
| Exiting plan | exits, travel distances, common path, exit discharge | stairs and corridors are sized and located |
| Accessibility | accessible routes, the unit matrix, accessible and adaptable unit locations | the unit matrix counts are set |
| Zoning tabulation | floor area, height, setbacks, open space, parking, any bonus incentives | the figures match the entitlement |
The fire separation guide and the podium code guide cover the rules most multifamily code plans are built on. The accessible units guide covers the unit matrix and the unit plans in California.
Plans
| Item | What the DD set shows | Closed when |
|---|---|---|
| Floor plans | every level with walls typed, openings placed, rooms named and numbered | unit layouts and the core stop moving |
| Unit plans | each unit type at a buildable scale with fixtures, casework and clearances | the unit types are final and counted |
| Core and stairs | stair and elevator layouts with rated enclosures and landings | the elevator model and stair dimensions are set |
| Garage or podium level | structure grid, parking count, ramps, trash, utility rooms | the grid and the transfer level are coordinated with structure |
| Roof plan | drainage, equipment zones, roof access, any occupied roof | equipment locations come back from the consultants |
Sections, elevations and envelope
| Item | What the DD set shows | Closed when |
|---|---|---|
| Building sections | floor-to-floor heights, the podium transfer, roof structure depth | the heights fit the zoning envelope |
| Exterior elevations | materials, openings, balconies, the expression of the base and the top | the owner approves the elevations |
| Wall sections | each envelope assembly where it changes | the assemblies are named and rated |
| Window and storefront | types, sizes and performance targets | the window system and its energy values are chosen |
Assemblies and schedules
| Item | What the DD set shows | Closed when |
|---|---|---|
| Wall types | every partition and exterior wall with rating, sound rating and listing | the types are built in the model and used on the plans |
| Floor and roof types | each horizontal assembly with rating and sound rating | the structure and the finishes are coordinated |
| Door and window schedules | types, sizes and ratings, live in the model | counts match the plans |
| Room finish schedule | finish levels by room type | the owner's finish standard is set |
| Outline specifications | major materials and systems by division | the owner and the estimator accept them |
Consultant coordination
| Item | What the DD set shows | Closed when |
|---|---|---|
| Structure | grid, transfer level, shear wall or core locations, slab and framing depths | shear walls are located on the plans |
| Mechanical | system type, equipment locations, main duct and shaft routes | shafts are sized and located |
| Plumbing | stack locations, water heating strategy, drainage | stacks align from floor to floor |
| Electrical | service location, meter rooms, unit panel locations | the electrical room size is set |
| Civil and landscape | grading, utility connections, stormwater, planting areas | points of connection are confirmed |
| Energy | the compliance approach and target values | the envelope and systems match the energy model |
The Title 24 guide covers how the energy forms and the drawings have to agree in California.
What must close before CDs start
A short list decides whether CDs go fast or get redrawn. Before the CD phase opens, the practice and the owner should be able to answer each of these in one line:
- Construction type and sprinkler standard, since they set every rating in the set.
- The unit types and the unit matrix, since every enlarged plan repeats them.
- The wall, floor and roof types, built as Revit types and used on the plans.
- Floor-to-floor heights and the transfer level, fixed with the structural engineer.
- Shaft and stack locations, fixed with the building systems engineers.
- The window system, chosen with its energy values.
- The finish standard, at least by room type.
- The deferred submittals, listed, so the CD set can show them.
Owner approvals and pricing at DD
The DD set is usually the set an owner prices. A general contractor or a cost estimator reads it for quantities and systems, and the owner's lender and equity partners often see the resulting budget. That makes three items in the set matter more than their drawing time suggests:
- The outline specifications, since they set the quality level an estimator prices;
- The wall, floor and window types, since the estimator counts them;
- The unit count and unit mix, since every pro forma is built on them.
An owner approval at the end of DD is the practice's protection when a decision changes later. A short DD approval letter that lists the items fixed, with the set's issue date, is the record the CD phase builds on.
Gaps that show up at the end of DD
The same open items tend to surface on multifamily projects when CDs start:
- Shear walls and transfer elements located by the structural engineer after the unit plans were drawn, so units move.
- Shafts sized late, so corridors, closets and kitchens give up space.
- Window systems chosen after the energy model was built on placeholder values.
- Trash, mail, bicycle parking and utility rooms left schematic on the ground floor.
- A sound rating target for the unit separations never set, so the wall and floor types change in CDs.
Each one is a single decision in DD and a sheet-by-sheet revision in CDs.
How long DD takes on a multifamily building
No standard fixes a duration for design development, and the right length depends on how settled the scheme is at the end of SD. What the checklist above shows is that DD's length is governed by the consultants as much as by the drawing: the structural engineer locating shear walls, the building systems engineers sizing shafts, the energy consultant running the first model. A DD schedule that gives each consultant a background early, and a date to return it, closes faster than one that waits for the plans to be finished before sending them out.
The model at the end of DD
The way the DD model is built decides how much of CDs is drawing and how much is rebuilding. A DD model ready for CDs has:
- walls, floors and roofs built as typed assemblies, with no generic placeholders left on the plans;
- rooms placed and tagged, with areas the tabulation reads;
- door and window families with type marks that drive the schedules;
- views and sheets set up from the office template, so the CD sheet list starts populated;
- consultant backgrounds linked, with the current issue named.
The Revit template handoff guide lists what an outside team needs from a practice's template before it touches the model.
Where the studio fits
TECTO Studio draws design development in your Revit model and on your template: typed assemblies, unit plans, sections and live schedules, with consultant backgrounds coordinated and every open decision logged for your office. The design development page describes the work.
Sources
- AIA Contract Documents: B101-2017 overview
- AIA Document B101-2017, Section 3.3.1 (design development documents, paraphrased here), as reproduced in the South Carolina Office of the State Engineer sample
- IBC 107.3.4.1, deferred submittals (UpCodes)