DDFD and the Holy Grail
One of the greatest challenges in our engineering industry is determining when a project is truly done. How do you know when a design is sufficiently complete so that the contractor will have no basis for cost-impact RFIs and change orders? How do you know when you have used your time the most wisely, such that the project is complete enough, but not so overly detailed that you have wasted your time? Ask 10 different people and you will get 10 different answers. Ask 100 people and you will get the same outcome.
On the contracting side, how do you know when your project is truly complete? Is it when you have sign-off from inspections? Is it when the occupant moves in? Is it when you have received all of your retainage? Is it when the warranty has expired? Is it when the statute of limitations for litigation has expired? The question is as hard to answer in the contracting world as it is in the design world.
My firm is a design-build firm, so we must address this question from both perspectives. At project completion, engineers and project managers alike both have to answer our CEO’s question about if it is done. Our CEO has an expression for done, which is known as DDFD. This is an acronym for “Done Done F&@#ing Done!”
The typical project conversation goes like this.
CEO: “Is it done?”
CEO: “Is it DDFD?”
You: “Yes, except…”
CEO: “So it isn’t DDFD.”
You: “Uhhh… no.”
It reminds me of the scene from Monty Python and the Holy Grail when the knights are at the Bridge of Death and are being questioned by The Enchanter (some call him… Tim?).
Enchanter: “Who would cross the Bridge of Death must answer me these questions three, ere the other side he see!”
Knight: “Ask me the questions bridge keeper, I am not afraid.”
Enchanter: What… is your favorite color?!”
Knight: “Blue. No… yellow!”
At which point the knight proceeds to fly off the bridge to his death. It’s just like DDFD. Is it done? Yes. Except… ARGH!
Theatrical analogies aside, there is great significance asking about DDFD in the engineering industry and if you provided sufficient detail for the contractor(s), but not too much, Too much detail means that it is superfluous or even contradictory to reality. You are telling the contractor something he doesn’t need to know, or something that is incorrect.
Let’s get into a few examples. “Done” includes the obvious:
- Space allocations have been established in pipe chases, mechanical spaces, and ceilings
- Main drain line pipe elevations have been approximated and roughly coordinated with structure, ceiling heights, and other trades
- Utilities are coordinated with the civil engineer
- Load letters have been sent to the utilities where required
- Pressure zones have been established
- Calculations are complete
- Piping is drawn and sized on plans and riser diagrams
- Equipment is scheduled
- Materials have been selected
- Necessary details have been provided
- Fixtures are specified, at least in concept (always a moving target)
- Needs of or from other trades have been coordinated (M&E, general contractor and/or equipment vendor)
- Acoustical requirements have been addressed
- Geotechnical requirements have been addressed
- Submissions have been made to the necessary agencies (industrial waste, etc.)
This list could go on at great length. What’s most important to consider is that you have given the contractor enough information to detail and build the job without a plethora of questions. Many of us engineers are prone to thinking the contractor will figure it out. And, this may be true. But, will they figure it out the same way you would figure it out? And, is it fair to make them complete the engineering that you have not done?
Here are a few more examples. Many engineering documents I see have dozens of standardized details provided on the detail sheets. They might include pipe hangers, seismic bracing, fire proofing, water proofing, and so on. How often are these details actually coordinated with the project specific requirements? In other words, are they real details? Or are they cartoons?
Usually, in my experience, fire proofing and water proofing details are addressed by the architect. But, even those may be cartoons since the fire stopping contractor and water proofer might have very different intentions from what the architect has shown. Architects, too, are sometimes guilty of regurgitating standard details from project to project.
Pipe hangers are usually dictated by code and the contractor’s bill of materials. You might provide a generic detail that would add unnecessary cost to the project, or it might get the contractor into a fix with the inspector should they choose to hold the contractor to every element on the details.
What does the contractor really need to know? The most frequent debate I come across is whether or not the hot water hangers can be encapsulated, and if inserts are required for non-encapsulated insulation. Address the question correctly on the detail sheet or in the spec and you will be doing the contractor and the project a world of good.
Other necessary but seldom seen details might include:
- What are the dimensions of the equipment pads?
- Does the equipment fit?
- Are the edge of pad anchorage details correct, and has the equipment anchorage been addressed?
- For rooftop equipment, has the water proofing at equipment pads been addressed, either by you or the architect?
- Are roof top vent pipes sufficiently far from ventilation air intakes?
- How will the waterproofing of overflow drains through the building façade be addressed?
This list, too, could go on at great length. It would help if every engineer put their mind into the mode of a contractor and thought about what they would need to know if they were to be building. Having never been a contractor, it might be a very hard question to answer well. But, it never hurts to try. Never hesitate to have the dialog with your local contractors.
Timothy Allinson is a senior professional engineer with Murray Co., Mechanical Contractors, in Long Beach, Calif. He holds a bsme from Tufts University and an mba from New York University. He is a professional engineer licensed in both mechanical and fire protection engineering in various states, and is a leed accredited professional. Allinson is a past-president of aspe, both the New York and Orange County Chapters. He can be reached at firstname.lastname@example.org.