I’ve been thinking about the issue of “productivity” and the debate over one-person (lead carpenter concept) vs. two (or more) person crews.
When I open up my estimating application or crack open a copy of R.S. Means’ Repair and Remodeling Cost Data I might see a line item that looks like this:
|Description||Crew||Daily Output||Qty||Labor Hours|
|Interior,passage door, 4-5/8 solid jamb,Luan finish, solid core, 1-3/8″ x 6′-8″ x 2′-6″ wide||
Lets say I have a job to install twenty of just the door they are describing there. I’m going to use that .800 Labor Hours figure times the number of doors (20) to come up with a figure of 16 Labor Hours to install the twenty doors. While I think that generally speaking hanging doors is a solo carpenter job I can see there that R.S. Means has based there figures on a two person crew. I going to interpret that to mean that while they may see the task as primarily solo too they feel there are times when having and extra set of hands can sometimes help so the .800 Labor Hours per door figure is based on that. So I go with that and let that be my guide.
I will then take that 16 Labor Hours to install the twenty doors and then multiply it by my Loaded Labor Rate of $85 per hour to come up with a Price of $1360 to install those doors. My Cost Estimate is done.
The text I’ve highlighted in bold red goes to so questions I have regarding productivity. When I first began to look at the topic of “How long does it (really) take to do something that’s been estimated to take 200 labor hours?” (JLC-Estimating & Markup Forum—Estimating Conundrum #2 How long… March of 2003) I was trying then to look at it in almost a generic form without looking at the issues of crew size so that I could examine some very basic scheduling issues.
The truth of the matter ( and there were plenty of people who brought it to my attention back then too) is that there are very very few tasks in general building and remodeling that productivity isn’t effected by crew size.
While (I used to) hang doors all the time and I still recall my own personal solo record of 17 in an eight hour day back in ’96 I also recall that I almost killed myself doing it and it took me days to recover from it so while I might have been ultra productive that one day I sure the days that followed were below average performance.
Regardless I mentioned above that while I personally see hanging doors as a solo carpenter activity (I could be wrong about that) I really see it done most efficiently by a two man crew so that on those occasions where you need an extra hand you don’t lose you productivity because your struggling to physically.
Despite what Walt Stopplewerth and the HomeTech school of thinking people seem to be advocating regarding using a one man crew I’m not at all convinced it’s the most productive way to get things done.
What Crew Types Do You Use When Determining Labor Costs?
The simple answer is ‘all types of crews’. We do not believe that the price for a specific amount of production changes depending on the crew mix. Let me give you an example. One contractor uses an experienced lead carpenter to do framing by himself. Another uses an average carpenter with a helper. The first contractor pays the lead carpenter a total of $30 an hour and he finishes the job in 10 hours. His cost is $300. The second contractor pays his carpenter only $22.50 an hour and the helper $15 an hour and they finish the job in only 8 hours. His cost is also $300. Both companies used different crew mixes but the per unit or per job cost is the same.
We have found that with stable, profitable companies, crew mixes do not substantial change the unit costs. So if you are paying your employees what they are worth, 100 square feet of wall framing should cost you the same whether you use a one or two man crew.
One problem I have with that is it just doesn’t quite work out that way in the real world. While not true of every task there are a lot of gains to be made at time by just having that extra time or perhaps it’s better stated that the extra time it takes to do a particular task all by yourself can be eliminated by having that “extra hand” on call from time to time.
But again,… it depends upon the task. And it certainly worth keeping in mind what is spoken about in software development circles as Brookes Law: “adding manpower to a late software project makes it later” which also has it’s humorous corollary “Nine women can’t make a baby in one month.”
- It takes some time for the people added to a project to become productive. Brooks calls this the “ramp up” time. Software projects are complex engineering endeavors, and new workers on the project must first become educated about the work that has preceded them; this education requires diverting resources already working on the project, temporarily diminishing their productivity while the new workers are not yet contributing meaningfully. Each new worker also needs to integrate with a team composed of multiple engineers who must educate the new worker in their area of expertise in the code base, day by day. In addition to reducing the contribution of experienced workers (because of the need to train), new workers may even have negative contributions – for example, if they introduce bugs that move the project further from completion.
- Communication overheads increase as the number of people increases. The number of different communication channels increases along with the square of the number of people; doubling the number of people results in four times as many different conversations. Everyone working on the same task needs to keep in sync, so as more people are added they spend more time trying to find out what everyone else is doing.
While Brookes is talking about software development I am sure intelligent builders and remodelers can see how this applies to building and remodeling projects too.
The answer I think is just don’t throw bodies and resources at a project and expect it to get done faster. You need to design and engineer the work flow process to succeed.
In another article from the Home Tech web site on the Lead Carpenter Method: Home Techs Lead Carpenter Concept Overview:
Studies of remodeling have shown that the one-person crew is the most efficient: that first person is 80%-100% efficient, the second is 25% efficient, and the third is minus 5%.
While I never been a fan of the one man crew idea for safety reasons alone I also have to wonder,…what are those studies? This is one of my favorite pet topics and I have found tons of studies and papers on productivity over the years and I have never seen on that states that conclusion. Hey Home Tech how about a footnote?
My thinking,….well it depends upon the task and how that task is organized and planned in relationship to other tasks.
While it is possible (I’ve actually done it a couple of times) one man alone cannot (or should not ) really install a shop built stair by himself. But then again after the stair is installed to get the newels installed and the balustrade ready for installation doesn’t take two carpenters. But then again when it come times to install that balustrade once all the prep is done two or three hands makes short work of that process where one person would struggle with it for a while with a lot of wasted time and effort.
It makes perfect sense for the stair installer to have two other carpenters working on a non critical chain/path activity such as maybe running trim or hanging doors that he or she can interrupt and call away for assistance for a few minutes.
However (and while its unlikely in this sample case I’m making) if those other two carpenters are instead working on the critical chain/path task then calling them away slows and delays the completion of the whole project so the stair installer in interest of getting the whole project completed in the shortest duration of time is then better off , or the project is better off, with him or her finding a way to do it alone.
In other words it depends upon the overall project’s organization and logic.
So getting back to the point I’m looking to gather some thoughts on whether there is a big enough difference in productivity between a solo trades person and a two person crew that we need to really to go nuts paying attention to that when were estimating and then scheduling? When does it matter and when doesn’t it?
How do we “Think Lean” about this?
What are your thoughts?