Lean Roofing

Finished Roof
My finished work

Recently I had the opportunity to do some roofing for my parents on their garage. It was good to get on the tools as it is not something that I get to do very frequently anymore. It reminded me of my youth working on the family farm and the numerous projects that I found myself involved in, back in those days I was always looking for an easier way to do the work. Fast forward all these years and I have a vocabulary to describe what I was seeing back then.

Being a Lean practitioner I have some ability to see non-value added work vs value added work. I am able to describe the wastes that I saw. I was also able to help myself by trying to structure my work in the most effective way possible. Now, I do say try as I was unfamiliar with the work. My knowledge on the subject comes from the building science that I have gleaned from working in the industry for a number of years, watching a few YouTube videos and reading the manufacturer’s packaging on the shingles themselves.

Work can be broken down into Value Added tasks, necessary but non-value added and obvious waste tasks. Value added tasks are those that give the client/customer what they want. It is the transformation of goods into the product that they are willing to pay for. Or in other words it achieves the form and function that they desire. In my case, my parents wanted to have a roof on their garage that matched the roof on their house that they had replaced last year. The function is that it protected both the structure, to maintain their property value, and to protect the contents that they hold within the garage. So any task that is not working directly to that goal is not of value to them. Non-value added tasks break down into two main categories, necessary and pure waste.

There were times that I would have to pause from installing shingles to plan out the next steps, or when I was doing cuts on the edges, I had to plan out the next few rows. This was mostly because I was just learning the trade of roofing and was figuring out what the next step was. At the start of the roof I was consciously competent of my lack of knowledge of the task ahead. It took a lot of effort to plan out each step. It would get a bit overwhelming if I thought to far ahead and all the tasks I needed to do to complete the roof. As I progressed through the work I became more competent in the tasks and I was able to focus on more things around me, like the pure waste that I was observing.

The pure wastes that I was observing are frequently known in Lean as Muda or the 7 wastes through the pneumonic TIMWOOD. They are Transportation, Inventory, Motion, Waiting, Over-processing, Over-Production and Defects. I tried to reduce many of these wastes but as it was a one off project for me and I was unskilled in the set-up I did not get them all in my first run.

Transportation waste has to do with unnecessary movement of material and equipment. I tried to reduce this waste in several ways. My mother and I went to the store in one trip to get the material required. Though the hardware store sent us home with the wrong nails so that required a second trip to get the correct ones, which was pure waste. When we loaded the shingles on the roof, we only took up half of the lot as I didn’t want to have to shuffle them around once I got up there and installed a portion of the roof. I made a rule to that whenever I went up the ladder I had to take something up, so I would take a bundle up to conserve trips. Now, there was some transportation on the roof as the bundles were near the peak and I would have to bring a bundle down to where I was working. I got better at figuring out where to stage a few shingles so that I could maximize the tool time when I was using the air-nailer.

Material, nails and tools stage together

Inventory was kept low on the roof as mentioned above as each time it is moved it is susceptible to damage. Once the package is opened there is a risk of pieces being picked up by the wind and causing damage or injury. Also, this took me a few days, so I wanted to minimize the risk of a bundle sliding down the roof as well. It is good that I didn’t bring up all of the bundles as we had three left over and I would have had to bring them down off of the roof. The take-off that was done was based on roofing contractor completing the work. They tend to have more cut-offs then I did. I saved the cut-offs and used them in the next place that they fit. By the time I was done I had barely a handful of garbage for the waste bin.

Half the waste pile
This was half the wasted cuts

This leads into Motion waste, which involves any unnecessary movements to complete the task. As I mentioned I tried to keep a bundle nearby or stage shingles near where they were going to get installed. I tried to keep my hammer and shingle knife with me. But I had to measure and check and adjust several times as I wasn’t confident in my skills. Though I tried to keep my tools with me they were frequently not nearby and I would have to go and get them. Or I would run out of nails in the air-nailer. Now the air-nailer was a definitely a help to reduce motion, as four nails had to be put in each shingle and hand nailing those would have taken a long time and unneeded effort. My Dad, came up on the roof one evening and he was passing me the shingles and production was going really quick when I didn’t have to go and get more material or nails.

Waiting was not an issue on this project as I was doing all of the work and no process was held up waiting for the next process to start. There was no information that was required to complete the project. Even when my Mom went to get different nails, I had other tasks that needed to get done so production was not halted on the project. Another way to look at where I was waiting as mentioned above in the previous paragraph was when I was not attaching shingles to the roof the project was waiting for production to happen.

Over-processing is an easy one for me to do. This has to do with doing more work than is necessary to achieve the conditions of satisfaction from the client. Going above and beyond what is valued by the customer. This doesn’t mean not producing a quality product, it just means that I had to be aware of what the tolerances were. For example, the manufacturer’s instructions were to cut 6.5 inches off which was approximately 1/6 of the shingle. I could have gotten out a square and a measuring tape and cut each shingle to the exact length as described, but that wouldn’t produce and extra value. On the other end of the roof I was just going to trim off the excess and discard the rest. The trick is to know why we are doing certain tasks and to understand the tolerances required and to question them if they seem to high or too low. These should be communicated to the person on the tools so that they don’t have to make the judgement call. This should be also indicated by tolerances in specifications and production drawings. In this case the purpose was to offset the seams of the shingles so that the substrate was covered.

Over-production was like waiting and not really a concern as it was just me doing the work. Though it was windy so I didn’t put down the underlay membrane on the second side until I was ready to lay shingles on it as I didn’t want it getting torn off with the wind.

Defects is the last waste on the list. As I was not highly skilled in these tasks I made a few defects. I was aware of my conscious incompetence and started on the side that was not visible from the deck, so that I had space to learn. The shingles would come paired back to back and when I was starting I missed that I hadn’t separated them and nailed down a pair. There were a few slips of the knife that scored the shingle but some creative overlapping fixed that issue. As I was laying the shingles in a staircase fashion I did miss one of the lower steps once, which required me to pull out a few shingles and re-install new ones. I did like these shingles from Owens Corning as they had a fabric nailing strip on them which was a good visual on where to put the nail and it helped prevent it from going through the shingle as well. As the shingles look like shakes and its a dark color, I will admit that I did veer off course a little bit, but the shingles hid a lot of my high variation in the rows. It was not egregious but if you walk up on the roof you will see a little wave in the shingles.

The bonus waste that is frequently added is under-utilized talent. I can tell you that I was not under-utilized at this point for me signing up for the task. I gained in competence as I went and was glad for the experience. I think there is some value for people that spend their time in a managerial role to pick up the tools from time to time and get in the trenches with our craft partners as they help transform their raw materials into the products that our clients are desiring and paying for. It was also confirming to me that the Lean principles which I try and champion and share are apart of what I do and can also be seen by the guys on the tools if we help them see and trust them to make the work better and reduce the non-value added tasks from the work.

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