I've looked at many homes since the onslaught of heavy rains in the past few months, and I've seen a common theme: the lack of waterproofing techniques employed by "professionals." That term refers to people who get paid for their services. Many think "professional" implies that they know what they're doing. Their spokesman, usually the owner, probably does know how to do the job right, but I have found over the years that there are those who are most concerned with the appearance of the work, hoping to get paid quickly and move on. They gamble that any problems will be minimal and you won't call them back. They also gamble that their employees have done at least an adequate job, or that the weather for the next 20 years looks good.The most important thing to remember about exterior materials - brick, stucco, vinyl siding, wood or stone - is that they all need waterproofing materials behind them and around them to prevent water intrusion. Water gets in, as you've seen, because during those intense downpours, the atmosphere is so saturated and the air pressure so extreme that moisture moves in every direction, so the openings where water drips from also have water forced into them. Unless your house was carefully waterproofed with caulking and sealing around windows and door openings, at wall base connections, corners, wire and conduit openings, and any other kind of joint, it is not really waterproofed properly. Instead, the exterior material is relied on to do the job. Start at the top of your home. Analyze the roof, rain gutters and any penetrating elements, such as skylights, vent stacks and chimneys. Look for openings. Determine whether they're venting openings, which must be preserved, and whether they drain properly. Never seal a venting or drainage point. You may, however, need to check for backup waterproofing. For instance, a brick wall requires a backup membrane and weep holes at the base of the wall behind the brick. If you see holes in the brick joint every 16 inches or so, leave them alone. Sealing them will cause water to accumulate rather than drain.Work your way down the walls and around the windows. Is everything sealed? If you still can't find the leak, you may need to remove exterior materials in the area, but call a qualified waterproofing "professional" for a consultation first. Good luck!Readers are encouraged to send questions to: HERALD Homes379 Central Avenue, P.O. Box 220, Lawrence, N.Y. 11559-0220Attn: Monte Leeper, architect.