Ideally, 50 percent of the attic ventilation openings should be continuous soffit vents, and the other 50 percent gable, ridge or roof vents. Figure 5-15 shows various types of vents. Any of them are adequate when used in conjunction with soffit vents. Ridge vents are preferable where practical, but must be equipped with baffles to deflect wind blowing up the roof and to prevent the penetration of water and snow. Occasionally, a house will only have soffit vents. In this case, install gable end, ridge or roof vents to take advantage of cross ventilation.