Pre-planning is important when building a home. The cost of making changes during the design process can easily be 1000 times less then the cost of making the changes while a home is being built. For example it may only cost a few dollars for drafting changes to a plan during the design phase. However after the home is under construction it may cost several thousand dollars to make the same changes.
The cost of changing something can easily be 3 times as much as the cost of doing it right the first time. When you make changes you need to pay for the labor to undo previous work, labor to do the new work, labor for the original work, and the cost of wasted materials. For some types of materials you may need to pay a "restocking" fee to return an unused item to the store. You may also need to call back several subcontractors to redo work when changes are made.
Some items are difficult to calculate the cost of until the work is finished. For example the cost of digging a well may not be know until the well is dug and the cost will be directly related to how deep the well needed to be drilled. If large rocks are found while digging the foundation then this may be an added expense. A construction contract may have some items that are called reimbursable expenses and those costs may need to be added in to the final cost of the home.
"Have your home tested for radon gas, especially if it is a basement. Most basement homes will need an active radon mitigation system, so plan on it. Consider installing an active system regardless of the reading, therefore you are ensured low levels of radon all the time."
The above picture is an active radon mitigation system with the fan installed in the attic.
"The one piece of advice I can give you is, do what turns
you on. Do something that if you had all the money in the world,
you’d still be doing it. You’ve got to have a reason to
jump out of bed in the morning."
~ Warren Buffett: