The short answer is; Some defects take time to show up, and my not be apparent to an untrained eye.
All builders supply a one year warranty with a new home. This covers things like defects in workmanship and/or materials. While some of these defects are readily noticeable as you get to know and live in your new home, ex; cosmetic defects, or appliances problems, some issues may not show up until later. An 11-month warranty inspection identifies the hidden or more difficult to see defects. These can range from small unnoticeable roof leaks, electrical wiring deficiencies, poor ventilation, incorrect landscape drainage, among others. These hidden defects, if not corrected early, can cause substantial damage in the future. You need to have these hidden defects uncovered and documented before your warranty expires, and before all the repair cost (which can be substantial) falls on you.
I've been in the home construction/home remolding, and home inspection industry for over 30 years. I've personally/hands-on completed installations and/or repairs on every system in your home. I use that extensive experience and knowledge to identify potential issues a lesser experience inspector may miss. This is where Advantis Home Inspection comes in, to apply the experience and training, and to not only identify problems, but to give you the necessary documentation to enforce your warranty with the builder.
Every 11th month warranty inspection includes a FREE !! INFRARED SURVEY by a fully trained and CERTIFIED RESIDENTIAL THERMOGRAGHER (CRT), as well as a FREE !! FOUNDATION LEVELNESS CHECK. IF your builder missed installing some insulation, or perhaps a pipe joint is failing and leaking, an infrared inspection will identify these items. And wouldn't you want to know if your foundation is starting to sink--before it becomes an expensive issue YOU have to pay for?
You should schedule your 11-month warranty inspection during the 10th or 11th month of your first year in the home. Most, though not all, issues should show up by this time, and having your warranty inspection done early gives ample time to notify your builder, and have repairs completed before your warranty runs out.