DIY-Prefab

Once design issues have been taken care of a good material handling strategy is key to making a commercial prefabrication operation work smoothly. While it is less important for a small project it can still be helpful. Material handling as I am thinking of it now includes all aspects of the acquisition and movement of materials through your prefabrication operation – large or small. It should go without saying but it is crucial for efficient construction to have the materials you need where you need them and when you need them. How many times have you tackled some relatively small project that should be simple and quick but that ends up taking way more time that you thought it would because you had to make unexpected trips to the store for something you did not plan for.

I have already mentioned that careful planning for prefabrication might help you avoid mistakes in how your project goes together. Careful planning also enhances being able to create accurate parts lists. For even simple home remodeling projects I try to think out the steps that I am going to have to take before I go shopping. I try to anticipate unexpected things and will often buy a few different parts that I may not need with the understanding that taking a few unused parts back to the store for a refund may be a lot more time efficient than having to make unexpected trips right in the middle of what you are working on. I give extra attention to this when I anticipate having to turn off the water or the electricity to do what needs to be done.

Besides carefully dealing with the acquisition of material thinking about the movement of the material through your workplace is key. This is especially true if you modify parts that you have acquired or if you have to fabricate subassemblies. One of the main aspects of parts modification that you will want to carefully consider for a DIY prefab construction project is your cut list. There are likely to be a lot of pieces of material that need to be cut to different sizes. As I mentioned earlier you also need to decide whether you are going to store cut pieces by size or by specific panel. If you are working by yourself it is a bit easier to keep track of things but if your project will be worked on as your spare time permits a little organization can go a long way.

Setting up a tool to make a particular cut might not take all that long but if you have to do it too many times your efficiency will be reduced. Planning ahead might suggest that you make all of a particular type of cut at the same time.

One other issue that I think is well worth mentioning has to do with where your larger subassemblies are built. Large prefabrication operations tend to favor an assembly line approach where materials might be cut in one location and then various parts of the assembly are done in different stations along an assembly line. The panel company that I worked for had a large framing table where workers assembled the wall studs and nailed them together. The panel was then slid along a conveyor to another station where the plywood was attached. There was a nailing station and another station where the window openings were routed out. Wall studs were cut at a station near the framing table and plywood sheets were cut at a different station near the sheathing table.

An alternative approach is to have a single assembly table where all the work on a given panel is done. For a large operation you would just need to have more assembly tables. You would also have to have workers that were more broadly capable since each person would be performing more kinds of tasks. I contend that this approach can allow a panel operation to start on a smaller scale and grow as necessary. I also think that the overall equipment costs could very well be lower for a given capacity of panel manufacturing. There would at least be fewer conveyor rollers in the shop.

For DIY prefabrication you will probably want to lean in favor of the single assembly station both for reasons of space limitations and because you might be the only person doing the work.