Best practices - estimating hours required to complete project design?


I'm working for a firm that seems to be clueless in regards to project management. I haven't been here long and am beginning to take over a larger office management role (in addition to the projects I am managing). I'm trying to get things back on track for our projects that are currently underwater schedule-wise. I'm also wanting to avoid these issues in the future, but I don't know what a good rule of thumb is for estimating the amount of hours you believe will be required to complete a project. Mostly, my concern is with SD through CD.

Soooo......Say, if I cartoon a construction set and decide it will take X number of sheets for complete many days to complete each sheet?

Is there a formula like this that people like to use as a go-by? Assuming a completely middle-of-the-road, standard project with standard complexity. Not too easy, not too hard.

Thanks in advance!

Mar 10, 13 5:13 pm

one project on year.

Mar 10, 13 5:50 pm

not helpful

Mar 10, 13 6:17 pm

Compare and base it to arch school.. 1 final project in 2 months, all on your own ;)


^ don't forget having to juggle few other courses, classes, tests, assignments :P

Mar 10, 13 7:55 pm

i've been out of school for five years and have been managing projects for most of that. I guess a better way to phrase the question is how to estimate man-hours per sheet. I know there are generally accepted rules of thumb for this. Anybody?

Mar 10, 13 8:02 pm

In the past we have used 40 hours per sheet as a rough estimate.

Mar 13, 13 12:47 am

In my opinion, there is no such thumb rule that can determine an estimated time well in advance to complete a given project design assignment. The project completion time generally depends on various parameters, including client requirements, size of the project team, their expertise in project design, and so on. These parameters will normally vary from project to project, and from company to company. 

So, it is not possible to decide an accurate estimated time to complete a project design assignment unless you are a well established organization in the industry. 

Mar 13, 13 3:07 am

per sheet doesn't seem the right way to go.  the code summary sheet isn't going to take 40 hours, and a section sheet will go a lot faster if your 'designer' designed something buildable.  an elevation of a box building is really about as simple as drawing a rectangle, but if you have to figure out a bunch of roof pitches or draw in a lot of windows or something it will take a lot longer.

Mar 13, 13 7:39 am

Methinks you're asking the wrong question.

It's not a question of how many hours a project "should" take or hour many hours a drawing sheet "should" require -- isn't it more a matter of how many hours can you afford to spend on design and production while still making a profit?

You have to start with your "gross fee", or your best estimate of what the gross fee will be if the project is not yet under contract. Subtract from that number any consultant fees and any other direct expenses to determine the "net fee". Then, subtract from the net fee your desired profit on the project (usually 10% to 20" of  the gross fee). This leaves the total amount of money available internally for project delivery -- let's call this the "production budget".

Then, allocate the production budget among the various phases of the project. This schedule can vary widely, depending on many factors. However, this is a fairly common structure:

Schematic Design:         15%
Design Development:    20%
Construction Docs:         40%
Bidding/Negotiation:         5%
Contract Admin:               20%

Since you appear primarily concerned with the design and documentation phases, take 75% of the production budget (or whatever % is appropriate to your situation) and divide that number by the average "full cost" of labor assigned to the project -- "full cost" will be the average hourly wage rate for the employees working on the project, plus a multiplier to cover employee benefits (usually around 30%-35% of the hourly wage, plus an overhead multiplier (usually around 100% of the average hourly wage) to cover the cost of the office, liability insurance, etc.  This will give you the number of hours available to complete the project and still achieve your target profit.

If you've done a cartoon set for each design and documentation phase, then you'll know how many sheets will need to be produced. Divide the number of hours calculated in the paragraph above by the number of sheets and voilà you have an estimate of the average number of hours you can afford to spend per sheet and still make a profit. As was pointed out above, some sheets will require less hours than the average and some will require more hours than the average. Nevertheless, this calculation will give you a rationale basis for planning and managing the work.

Obviously, you'll need to make appropriate adjustments to the above to reflect the actual circumstances in your firm and the project(s) in question. But, this will give you a basic methodology to plan and manage your project(s).

Hope this helps.

Mar 13, 13 10:54 am

Parkinson's law states: Work expands so as to fill the time available for its completion. If you have 3 days to get it done, it will take 3 days. If you have 3 weeks, it will take 3 weeks.

Mar 13, 13 11:25 am

The time necessary to complete project phases is highly variable and dependent on a wide range of factors including type of project, in-house experience and efficiency, meddling of management, philosophy of the firm, quality of client and contractor relationships,  change orders, etc. etc.

I suggest examining time records of previous projects (assuming they have some pertinent information) as well as implementing a tracking system where staff tracks activity on their time sheets (if they don't already). You should get to know every member of the staff, observe how they are being utilized (or misused), and attempt to determine their individual and collective strengths and weaknesses,

It will probably take a few projects to build a picture of relative efficiency at which point you can begin to implement various strategies to improve production.

Good management is not top-down but rather a collaborative process. You want to engage the staff by identifying (and hopefully eliminating) their frustrations, maximizing their potential and improving their work environment. A happy office is a productive office.

Mar 13, 13 11:31 am

Thanks for some great responses! I know each project is unique and complexity, etc make such an exercise as my request nearly irrelevant...HOWEVER, my purpose is really to just get a baseline to begin with. If I can cartoon a set and than say lets start the project schedule assuming 40 hours per sheet (as above49 stated), I have a starting point that can expand or contract as we add or subtract project variables. I'm not using this as a hard equation to plug and chug numbers from. Either way, I appreciate all the well reasoned responses and think I have a lot to go off of now as I start helping these guys put together realistic project schedules in the future.



Mar 13, 13 12:16 pm

keep in mind, too, that within a phase or even the drawing set, some tasks and drawings take longer (almost always).  For instance, a detailed and heavily noted set of floor plans may take well over 40 hours per sheet whereas, as noted above, some other work is much quicker.  so if you use your cartoon set to estimate time, some sheets equal way more than 40 hours and others way less.

also, triangulating is useful.  chances are, estimating based upon what you can afford to do versus evaluating based upon your cartoon set heuristic versus a critical path assessment of work versus an assessment of hypothetically assigning available people to the work and, knowing their tendencies, estimating their time, will all yield different estimates. 

But the various estimates define a range and the actual time is more than likely somewhere in there. 

Aug 20, 13 3:36 pm

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