Builders gap is a gap between the top of the fascia board (where the gutter is attached) and roof decking (plywood or 1x6). This gap is a result of when the roof decking is stopped short and is not flush with the fascia. Builders and carpenters may tell you that the gap is meant to help with airflow throughout the attic, well this may be true, but there are also ridge roof vents, soffit vents, gable vents and many other areas for air to flow.
Can water get in my attic via this gap?
Generally speaking no it won't because the water will flow over the shingle into the gutter. In fact this gap is really noticeable from the ground.
Okay then what is the big deal why is this a problem?
Areas of builders gap are the perfect place for pests and unwanted wildlife to enter your home via the attic. Most often, it is squirrels, occasionally the gap is large enough for raccoons or even snakes and bats! Animals can use this gap as a "secret garage door" and literally nudge up the shingle and slip right inside!
Why did this happen and how could I prevent this?
Well like I said it goes back to the carpenter or framer or roofer. These gaps are vulnerable to animal entry, but not an issue in regards to the elements or rain or energy loss. Therefore, most contractors are not too concerned about animal entry when building a home.
As for prevention, there's not much a homeowner could have done. I tell people everyday there's nothing wrong with the home, it's just a fact that it's a vulnerable spot for wildlife entry.
So if you hear noises in your attic, scraping scratching, scurrying, please have Solocal Wildlife Removal out for an inspection. Builders gap is 100% an area we will check and while it can be expensive it can be remedied.