In the last article we discussed creating a list of work items for your construction schedule. In this article we will discuss creating a flow chart of your work items.
Before we begin I would like to make a few comments of commercially available scheduling programs including Microsoft Project. These programs are based on a scheduling process called Critical Path Method (CPM) which was developed prior to the widespread use of computers. CPM is a great tool.
The programs that are based on the method are complicated to use. When we tried to switch to one of these programs we found we were spending far more time on updating the schedule than working the schedule. The updating process often produced unexpected results. And printing the schedule was time consuming and it was difficult to see the overall picture from the printouts. The title of these articles includes the word "Simple" and the method I am proposing is far easier to create and control.
I have always preferred the low tech approach which is writing each work item on one of those little yellow sticky notes and then arranging the notes in the order the work is preformed. If you do this on a large sheet of paper you can then connect the yellow sticky notes with lines and you have your flow chart. The advantage of the sticky notes is you can see the whole project as it develops and move the sticky notes to make corrections and revisions.
For the purpose of this exercise assume you complete one operation before you start the next. For example, list the rough plumbing; rough HVAC and rough electrical one after the other even though you are likely to overlap these items. In fact I highly recommend overlapping these trades because it will help them work as a team if they know each other. We will adjust for the overlap as we progress with the schedule.
Construction of the home, of course, does not take a single path from start to finish. When you have completed the roof interior construction and exterior construction take separate paths. Each will have its own path to completion. In our case the interior took much longer than the exterior
Once you have the entire schedule completed and you are confident it represents a practical schedule go back and add to each box (or sticky note) the number of days each work item should take and in parenthesis or with a different color the number of none overlapping days.
In the mechanical portion of the schedule the Plumbing, HVAC and Electrical would take fourteen work days if the work items were done one time at a time but can be completed in nine days by overlapping the work.
Next add up the non-overlapping days to complete each item on the flow chart so you have a starting work day for each work item. In the chart above the start work day is shown in bold just outside the upper left hand corner.
You now should have a practical road map to build the home but you are only half way there. Next you need to make sure all the materials are there when you need them. Go back to your list of work items and for each work item list any materials that need to be ordered and require a lead time. Some items will be obvious such as doors, windows and cabinets. Some are not so obvious. Do not absorb that items performed by subcontractors will be ordered by them. If you use a bath tub that requires three weeks lead time include it in the list.
I recommend you place orders for all critical items at the same time you start the project. Assuming you order all materials on day one of your schedule are there any items that will not arrive in time to be installed? When we started to use prefabricated wall panels and roof trusses we discovered that to get the drawing completed, approved by the municipality (many wanted to see design drawings on the trusses), into production and delivered took longer than building the foundation. We needed to order the wall panels and trusses more than ten days before we started the home or we had to wait for the materials. You can add boxes to your sticky note schedule (blue boxes on chart) if it helps you identify the flow and any lead time problems. I always add a box for confirming the order of critical item. To determine the start calculate backwards from the day you need to item on the jobsite.
Assuming I have made all this clear enough to follow you should have your complete road map of the construction project for your typical house. In my next article on scheduling I will address putting this all into an easy and usable format.
Original Content copyright 2011 Thomas Robinson