Estimating drafting time
Now we are venturing out and must submit shop drawings for jobs with multiple rooms with several elevations and 50 ln ft of base cabinetry with sinks, special plumbing for labs and other custom requirements. We have purchased pattern systems to automate this process, but nothing is fully automated.
How do you determine how much money to add to an estimate for drawings? Is it just experience, a formula, or some combination of the two?
What can I expect from someone with approximately 10 years of CAD experience? Should a drawing like this take a day, a week, a month?
If you are going to job the drawing out you can expect about $100.00 per D size page. Most drafting services will give you a quote if you ask them to. If you are drawing in house it will depend on your experience. In your 50' of casework, how many boxes are the same? How many different sections need to be drawn? If you are drawing the job from scratch it may be a day or two. If you draw your sections as blocks and save them for reuse, in a year or so you could do the drawing in a few hours or so. The great part of CAD is draw once, copy, stretch and scale after that.
A good rule of thumb if you’re going to use a drafting service is to figure 3 to 5% of the construction cost. Of course this all depends on the complexity of the job, and how many details and sections are going to be required.
I've been doing commercial casework for over 10 years. My rule of thumb is one elevation per hour for jobs over 50 elevation. Usually it takes me 15 minutes on simple casework and longer on custom pieces. The hour includes check prints. Job setup usually takes 4-6 hours regardless of the size of the project. But this is working with a very customized Autocad program. Keep track of your time and document.
In Excel, paste this in your eng. hours.
Amount of job = 150,000.00 (B5)
Materials = 3 (C5)
($/HR) = 35 (D5)
Percentage = 0.03 (E5)
Engineering hours = "85.71" (F5)
You can adjust your materials, $/HR and percentage.
The following formula goes under Engineering hours. (F5)
I have been using AutoCAD for about 12 years and 2 years on the board. I have been a CADD Manager, Senior Designer for about 7 years. We create 3D models of piping and equipment for petrochemical plants. I can tell you it's hard to say just how long it's going to take to complete a project. Every project is different!
I just break down the scope. Picture in your head the steps involved and how much detail you will need to create clear fabrication drawings that your fabrications shops will understand.
When you get a good idea of the hours required, double them! (Ha ha…)
When I break down a project I always give myself a buffer of 1/3 the time I think is going to take. Always tell the truth and don't let pressure make you think it can be done faster.
I also factor in some B.S. I think out of 8 hours you can only get about 6 good hours of work out of your CADD people. Make them get up and walk around about 10 minutes every hour. You will get better quality work out of them.
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