New homes are perfect, right? Not according to those who inspect them for a living. Knowing what problems are most common in new home construction might help would-be homebuyers sort out the best builders from among the throng.

The National Association of Home Builders (NAHB) and the American Society of Home Inspectors conducted a construction quality survey. New home inspectors identified the most common new home problems as flashing, roofing, grading and site drainage and ventilation.  There also were building code violations.

Flashing — the metal strips used keep water from penetrating into one surface from another — is a common source of new home problems. They are most apparent around chimneys — some 60 percent of inspectors say they find problems there. Flashing is also a problem on roofs, wood decks, windows and doors.

Ninety-two percent of the inspectors surveyed said improper installation was the most common cause of flashing problems.  A third of inspectors said flashing at doors and windows was missing. Flashing that was too short was other commonly cited problem.

Inspectors also encounter design problems, such as roof valleys that dead-end at walls. Other design problems include improper roof slope or pitch and ventilation.

Roofing on new homes is another problem area. Inadequate nailing was singled out as the main problem. Thirty-two percent of inspectors said inadequate nailing kept roofing from meeting manufacturer’s specifications. Sometimes there were too many nails, sometimes too few. In other instances, nails were too high or too low on the shingles.

Absent or missing felt, exposed nails, absence of a drip edge and poor flashing details are among the other roofing problems found by inspectors.

Grading and site drainage problems include siting the home so water drains toward it. Related problems include downspouts and splash blocks not effectively directing water away from the house and general compaction of the backfill.

Ventilation problems are most often found in the attic, roof, kitchen and bathrooms.  The most common defect is exhaust fans vented into the attic. Improperly sized ducts are also found in many new homes. Blocked vents, mold and moisture problems and improperly installed vents are other often-cited shortcomings of newly constructed homes.

The kind of building code violations inspectors find include improper rail heights on stairs, ungrounded electrical outlets, loose wiring, flues too close to wood, inadequate flashing and water heater relief valve pipes that don’t extend to the drain or are missing altogether.

NAHB has a pre-settlement, walk-through checklist that might be helpful in spotting construction problems. Go to http://www.nahb.org/, and click on “For Consumers.” At the bottom of that section, click on “More,” and then “Building Your Home.” The checklist is the fourth item on the list.