Why Do Ridge Tiles Blown off?

There are a few different causes of missing tiles or slates on your roof. The first is obviously weather. When wind and rain gets high and heavy, it can pull tiles out of their place, especially if they weren't fixed in securely. Secondly there's the possibility of nails wearing away.

Is it normal for roof tiles to fall off?

It's not normal. Tile roofs are made to last 40-50 years. So if you notice some tiles falling off your roof, there's a problem.

Will roof leak if ridge tile comes off?

Your roof will absolutely leak with missing ridge tiles, no “ifs” “ands” or “buts”. If you have damaged or missing ridge tiles on your roof you should definitely investigate into getting this fixed. While the damage may not be apparent immediately, it will eventually make itself known.