"Ask yourself, 'Why am I building something 10 feet wide if plywood comes in 4-foot-wide sheets?'" says Lisa Stacholy, of LKS Architects, in Atlanta. The same applies to stock windows and doors: Use manufacturers' off-the-shelf dimensions from the outset and you will save the premiums of custom fabrication.
Cost of custom doors: $1,500-$2,500
Cost of standard doors: $500-$800
SAVED: Up to $2,000