Even people who have been building for a long time have difficulty nailing down construction costs. The problem is that materials, labor, equipment rentals and trade contractor costs are being calculated for some time in the future. As economic conditions change, prices change. Underestimated costs often force owner builders to cut corners as the project progresses, affecting the final quality and value.
Costs also get underestimated by owner builders simply due to lack of experience and lack of reliable estimating tools. Good estimating software costs hundreds of dollars. Learning to use the software takes hours. An owner builder's problems in this area are amplified if she doesn't know building processes.
Higher Costs of Construction
Building a home is a complex project with multiple tasks dependent upon preceding tasks. There are costly mistakes that can creep into the process. For example, many large bath units must be brought into the bathroom before all walls are built. If the walls get built first, then part of them will most likely need to be removed to get the bath unit into the bathroom.
Not ordering the right quantities of materials causes work stoppages and more expense to get those materials to the job site. Owner builders often forget to plan for safety and security at the job site. The initial costs of not doing that might be minor, but one accident, or one sudden rainfall that damages materials, can easily add significant costs to the entire project.
Inexperienced people who build their own homes face a higher probability of making mistakes during construction due to their inexperience. Construction mistakes range from simple, easy-to-fix items, to major structural mistakes that require expensive retrofitting or removal of assemblies so that they can be rebuilt. Owner builders often make the mistake of assuming the inspector or code compliance official will alert them, but often the mistakes are already made by the time they are spotted by the inspector.
Procedural mistakes like not calling for inspections when they are needed can be a source of major problems. Once a foundation is poured, it is no longer possible to see the components that were used in it, or how they were put together.