Can someone please explain the differences of SD set, DD set, CD Set (20%, 60%, 100%, etc.), And why there are so many sets that need to be released?

[Elecestim123]

Tried to look it up as well, but I've never gotten a solid explanation.

Why do jobs need to be put out for bids so many times, instead of just maybe once or twice?

There can be 5 sets before the bid is final and they select a contractor. I heard some of it can do with the customer needing to get financing or something to that affect, but I'm not sure.

So basically:

1) What does each set mean exactly. What makes it 20% CD vs a 60% CD? Adding circuits to the laid out receptacles? Showing disconnects on the drawings for motors? Etc. Same for 60% vs 100% CD. Or 100% CD vs Permit set or whatever.

2) WHY does there have to be so many sets released? Why not just 1 or 2? What's the exact reasoning in detail? Would love to know some specifics.

Thank you!

 

[Jraef]

If they are involving you as an EC on a 20% CD level (sometimes referred to as the “cartoon drawings”), it’s kind of a compliment in that they trust you to help make suggestions on any glaring issues you see. But a dollar amount on a 20% CD is kind of a joke. 60% and up are where the project has been given a green light and they start looking at design changes to save money and/or make stakeholders happy


Here’s a way I look at it:

20% = “mortar shell” price, scares out the hidden pitfalls but nobody is taking it seriously yet.

60% = “hand grenade” price, close but no need to be totally accurate.

90%= “machine gun”, getting closer but you need to be prudent because you are still taking some chances with changes.

100%= “sniper rifle”, you are committed.

 

[petersonra]

A lot of times real drawings and specs are not available because the people paying the bills have not gone beyond the idea of building something, but don't know what the end result will look like. So, the engineers come up with something so they can get a WAG at what it will cost, and then this is refined over time.

It is all but impossible to separate the issue of cost from the design process, and getting some idea what that cost might be is an important part of the process. It tends to be an inherently iterative process.

Most of our projects go through several iterations before we see a P.O.

 

[gadfly56]

Tried to look it up as well, but I've never gotten a solid explanation.

Why do jobs need to be put out for bids so many times, instead of just maybe once or twice?

There can be 5 sets before the bid is final and they select a contractor. I heard some of it can do with the customer needing to get financing or something to that affect, but I'm not sure.

So basically:

1) What does each set mean exactly. What makes it 20% CD vs a 60% CD? Adding circuits to the laid out receptacles? Showing disconnects on the drawings for motors? Etc. Same for 60% vs 100% CD. Or 100% CD vs Permit set or whatever.

2) WHY does there have to be so many sets released? Why not just 1 or 2? What's the exact reasoning in detail? Would love to know some specifics.

Thank you!

Large projects in particular have a lot of moving parts, and it's important that the basics get ironed out before you hang the "gingerbread". There are frequently multiple end users and a finite square footage. I know at LaGardia Terminal B there were rooms changes well past the 100% CD phase.

Schematic Design, or "SD" is a very broad brush look. For fire alarm, you put your panels in and divide the footprint into fire alarm zones. These zones have to coordinate with the smoke control zones (if any) and the sprinkler zones. They also have to be mindful of where the rated fire separations go, since every boundary is technically a separate fire zone. Notification appliance zones have different maximum coverage from sprinkler zones. You can see how hard it might be to line up the fire walls, smoke control, notification, and sprinkler zones, and we're still in SD! For one trade. And we've still got evacuation travel distances to throw another monkey wrench into things. Detail Design or "DD" starts to add the devices. At first pass, you hang them anywhere on the drawing that gets you all the smoke detector and notification appliance coverages you need and max travel distances to pull stations. That might be 20% DD. Now comes the hard coordination issue. Maybe the wall that I hung a speaker strobe or pull station on is glass, and now I have to rearrange things, or a nice blank wall is going to be used for an art piece or information display, or the ceiling becomes a well between floors or changes from hard lid to acoustical tile. And the architect is going to want all the FA devices to line up nicely with all the other gear on the ceiling and doesn't necessarily remember that the smoke detectors can't be within 3 feet of the linear diffusers. These answers don't necessarily come all at once, so you might have a 40%, 60% and even an 80% DD phase. Construction Documents might have a 95% and 100% phase. This is where the stuff that was forgotten or last minute changes are accommodated.

For the contractor, unless this is a design/build project, you shouldn't be giving prices until the bid set comes out, which might be based on the 80% DD drawings and specs. If you're giving prices earlier without a contract, someone is using you as their quote bitch, because the design team's estimators should be handling the numbers up until this point.

 

[Elecestim123]

Large projects in particular have a lot of moving parts, and it's important that the basics get ironed out before you hang the "gingerbread". There are frequently multiple end users and a finite square footage. I know at LaGardia Terminal B there were rooms changes well past the 100% CD phase.

Schematic Design, or "SD" is a very broad brush look. For fire alarm, you put your panels in and divide the footprint into fire alarm zones. These zones have to coordinate with the smoke control zones (if any) and the sprinkler zones. They also have to be mindful of where the rated fire separations go, since every boundary is technically a separate fire zone. Notification appliance zones have different maximum coverage from sprinkler zones. You can see how hard it might be to line up the fire walls, smoke control, notification, and sprinkler zones, and we're still in SD! For one trade. And we've still got evacuation travel distances to throw another monkey wrench into things. Detail Design or "DD" starts to add the devices. At first pass, you hang them anywhere on the drawing that gets you all the smoke detector and notification appliance coverages you need and max travel distances to pull stations. That might be 20% DD. Now comes the hard coordination issue. Maybe the wall that I hung a speaker strobe or pull station on is glass, and now I have to rearrange things, or a nice blank wall is going to be used for an art piece or information display, or the ceiling becomes a well between floors or changes from hard lid to acoustical tile. And the architect is going to want all the FA devices to line up nicely with all the other gear on the ceiling and doesn't necessarily remember that the smoke detectors can't be within 3 feet of the linear diffusers. These answers don't necessarily come all at once, so you might have a 40%, 60% and even an 80% DD phase. Construction Documents might have a 95% and 100% phase. This is where the stuff that was forgotten or last minute changes are accommodated.

For the contractor, unless this is a design/build project, you shouldn't be giving prices until the bid set comes out, which might be based on the 80% DD drawings and specs. If you're giving prices earlier without a contract, someone is using you as their quote bitch, because the design team's estimators should be handling the numbers up until this point.

Very good info, thank you!