Construction Drawing Types Explained (SD, DD, and CD Sets)

Construction Drawing Types Explained: SD, DD, and CD Sets

A client called me last spring, pretty upset, waving around a set of drawings and asking why the number he was holding was forty percent higher than the one I’d given him three months earlier. Same house. Same architect, even. I asked him one question before I answered anything else: is that the same set you had in March?

It wasn’t. He’d been holding a schematic sketch back then. What he had in his hand now was a full construction document set, stamped, dimensioned, ready to permit. Nobody had explained to him that those two things aren’t really the same drawing at different stages of neatness. They’re closer to two different documents that happen to show the same building.

That mix-up costs more goodwill than almost anything else in this business, and it’s completely avoidable once you know what you’re actually looking at.

In this guide:

• Why This Confusion Keeps Happening
• Schematic Design (SD): The Napkin Sketch With Better Handwriting
• Design Development (DD): Where the Building Starts Making Decisions
• Construction Documents (CD): The Set You Actually Build From
• How the Numbers Move Between Stages
• A Side-by-Side Comparison
• How to Talk to a Client Holding the Wrong Set
• Common Mistakes
• Questions People Actually Ask
• Final Thoughts

Why This Confusion Keeps Happening

Architects move through design in stages for good reason. Nobody wants to spend six weeks detailing a stair that gets deleted in the next round of client feedback. The problem is that every one of those stages produces a drawing set that looks, to somebody outside the industry, basically finished. Lines, dimensions, a north arrow, maybe even some shading. It reads as done.

It isn’t. And the estimate that comes off it shouldn’t read as done either.

I’ve watched contractors get burned both directions on this. Some quote off an SD sketch like it’s a CD set and eat the difference when scope firms up. Others get so cautious about early drawings that they price in so much contingency the client walks. Neither one is really a pricing problem. It’s a not-knowing-what-you’re-holding problem, and it’s worth ten minutes to fix permanently. If you haven’t already, it helps to pair this with how to read construction blueprints first, since that guide covers the mechanics of a set once you know which one you’ve got.

Schematic Design (SD): The Napkin Sketch With Better Handwriting

Schematic design is the earliest stage that gets put on paper, and it’s meant to answer one question: does the general idea work. Room sizes are rough. Walls might not even be walls yet, more like zones where walls will probably go. Systems like HVAC and electrical usually aren’t shown at all, or they’re a single note that says “mechanical TBD.”

I tell people to think of SD as the stage where the architect is still arguing with the client about whether the kitchen should face the street. Nothing about the plumbing rough-in matters yet if the kitchen might move.

What you’ll typically find on an SD set:

• Rough floor plans, sometimes hand-drawn or loosely modeled
• Approximate square footage by area, not by room
• General massing and elevations, no material call-outs
• Site plan showing basic building placement, nothing detailed

What’s missing, almost always: structural sizing, MEP routing, finish schedules, door and window schedules, and anything resembling a dimension you’d want to cut lumber against.

An estimate off an SD set is a budget number, not a bid. Say that out loud to whoever’s asking for it. In writing, ideally.

Design Development (DD): Where the Building Starts Making Decisions

DD is the stage where the vague zones from SD turn into actual rooms with actual dimensions, and the building starts committing to choices it can’t easily walk back from. Structural systems get a first pass. Major equipment gets located, even if it’s not fully sized. Materials start getting named instead of implied.

This is usually where a contractor gets pulled in for the first real budget conversation, and it’s also where the most expensive kind of assumption creeps in: treating a DD set like it’s locked. It isn’t. Finishes shift. Equipment gets value-engineered out. A wall that was masonry in DD sometimes comes back as metal stud in CD because somebody looked at the number and flinched.

What generally shows up by DD:

• Dimensioned floor plans, room by room
• Preliminary structural framing plan
• Rough MEP layout, equipment located but not fully sized or routed
• Exterior material selections, at least tentatively
• Outline specifications, a paragraph or two per system rather than a full spec section

A DD-stage estimate is closer to real than SD, close enough that most owners start treating it as gospel. Worth reminding them it isn’t, the same way you’d flag a rough framing inspection isn’t the final walk-through.

Construction Documents (CD): The Set You Actually Build From

By CD, the arguing is supposed to be over. This is the stamped, permit-ready set: full dimensions, structural calculations behind the framing plan, complete MEP drawings with actual routing, door and window schedules, finish schedules, and a full spec book sitting behind the drawings even if nobody in the field ever opens it.

This is the only stage where an estimate should carry real confidence, and even then, only if the set is current. Revision clouds still happen at CD. Value engineering still happens at CD, sometimes more aggressively than at DD, because now the owner’s looking at real bid numbers instead of a budget range and reacting to sticker shock.

What a complete CD set includes:

• Fully dimensioned plans, sections, and details
• Structural drawings with sizing and connections
• Complete MEP sets, coordinated between disciplines
• Door, window, and finish schedules
• Full specifications
• Permit stamps and code compliance notes

If someone hands you a set and calls it “final,” check the title block for a permit stamp before you believe them. A stamp is the difference between a set that’s actually final and one that’s final until the plan reviewer sends it back.

How the Numbers Move Between Stages

This is the part nobody explains well, and it’s the actual source of that phone call I mentioned at the top. The swing between SD and CD isn’t a sign that anyone did their job badly. It’s the design process working exactly as intended, and it typically moves in one direction: up. Rarely does more scope get discovered on the way down.

A rough industry rule of thumb, and it really is rough, not a promise: expect an SD-stage number to land somewhere in the neighborhood of plus or minus twenty to thirty percent off the eventual CD price. DD tightens that gap to something closer to plus or minus ten to fifteen percent. CD is where you’re finally pricing the actual building instead of a placeholder for one.

The reason it moves is almost always the same handful of things. Structural sizing comes in heavier once an engineer actually calculates loads instead of eyeballing them. MEP systems get fully routed and suddenly need more duct, more conduit, more labor hours than a single note implied. Finish selections upgrade as the client falls in love with samples. And code requirements that got waved off early, accessibility, fire rating, energy compliance, show up in full once someone’s actually stamping the set.

None of that means the early number was wrong. It means the early number was answering a different question.

A Side-by-Side Comparison

How to Talk to a Client Holding the Wrong Set

The blunt version works better than the diplomatic one, honestly. Tell them plainly which drawing stage you’re pricing, and put it on the estimate itself, not just in a conversation that’ll get forgotten. A single line does most of the work: “This estimate is based on Design Development drawings dated [date] and should be considered preliminary pending Construction Documents.”

That one sentence has saved more relationships than any amount of after-the-fact explaining once the number moved. It’s a small habit, similar in spirit to tracking revision clouds on a live set, and it belongs in the same category as good construction project documentation: not glamorous, but the thing that keeps five people from remembering five different versions of what was agreed to.

Common Mistakes

Quoting a DD set like it’s final is the one I see most, usually from newer estimators eager to look decisive. Skipping the drawing-stage disclaimer entirely comes in right behind it, and it’s the fastest way to turn a normal design process into an argument about who lied to whom.

The other mistake runs the opposite direction: treating every early set with so much padding that a client can’t tell if you’re estimating the project or protecting yourself from it. There’s a middle ground, and it’s usually just honesty about what stage you’re looking at plus a reasonable contingency line that says so.

Questions People Actually Ask

Can I bid directly off a DD set if the client’s in a hurry?

You can price it, but call it a budget or a preliminary number in writing, not a bid. Plenty of fast-tracked projects do move forward this way. Just make sure everyone signing off understands the number will likely shift once CDs are issued, and ideally get that acknowledged in writing before work starts.

Why do costs almost always go up between SD and CD, never down?

Mostly because early drawings understate scope by omission rather than by mistake. Structural, MEP, and code items that aren’t drawn yet still have to get built eventually. Occasionally a value-engineering pass pulls a number back down, but it’s fighting against everything else that’s adding detail at the same time.

How do I tell which stage a set is at if nobody labels it?

Check for a permit stamp first, that’s the clearest CD marker. No structural sizing or MEP routing usually means DD or earlier. If room dimensions themselves look approximate or walls aren’t fully resolved, you’re most likely looking at SD.

Does this apply the same way on residential remodels as it does on commercial projects?

The stages are the same in spirit, though residential jobs often compress them, sometimes skipping a formal DD phase entirely and jumping from a rough sketch straight to permit drawings. Worth confirming directly with the designer rather than assuming based on project size.

Final Thoughts

None of this is about mistrusting drawings. It’s about matching your confidence in a number to the actual completeness of what produced it. An SD sketch and a CD set can show the exact same building and still deserve two completely different conversations with a client.

Once you know which stage you’re holding, the next piece is turning whatever’s on that sheet into a number you can stand behind. That’s covered in our guide on how to create accurate estimates Construction Drawing Types Explained.