In this YouTube video, the presenter is an experienced owner of a roofing company and highlights the most common mistakes in shingle roofing. They are as follows:
1. Wrong nail pattern or not enough nails
If you place nails too high on the shingle, then you will miss the top edge of the shingle below and leave too few nails in that shingle.
Most asphalt shingles need at least 8 nails holding them. When nails are placed too high, the shingle is left with only 4 nails and this can lead to it falling off the roof.
2. Using shingles on roofs that are too flat
Shingles are designed to be placed on the roof with a pitch of at least 2/12. They perform best on roofs with a pitch of 4/12. The slower water moves on your roof the more problems you are likely to have with it.
3. Poor pipe flashing installation
The most common problem here is nails that have been placed too close to the pipe flashing. Over time, the nails work themselves out and allow water to flow through the holes created by them.
4. Incorrect overhang of the shingles.
Shingles should not hang more than an inch and a half off the roof. Otherwise, they will crack and cause rotting and leaks.
5. Applying architectural shingles with a racking pattern.
These shingles may look nice to begin with, but in years to come they will begin to crack and cause leaks and other problems.