Q. We moved into our new house last spring. Although the attic seems to have plenty of insulation, the summer sun beating on the roof heats up the entire house during the day.

Is there anything we can do to help block this heat to keep the house cooler and reduce our air-conditioning needs? Is it necessary to add more insulation? I would like to do something about this problem before the hot summer months arrive.

A. Adding more insulation is not the answer to your problem. The sun beating down on your roof can easily heat your attic to more than 150 degrees. Much of this intense heat radiates down right through your attic insulation into the ceilings below.

The easiest and most effective do-it-yourself method is to install radiant barrier foil under your roof rafters and add more attic ventilation. Sheets of foil can be stapled on the underside of the roof rafters. The heat is then trapped between the foil and the roof. This heats the air, and it naturally flows up and out through the vents, drawing in cooler air. Double-sided aluminum foil, which is shiny on both sides, is recommended. However, you can substitute a less expensive single-sided foil and achieve almost as much protection.

If you select the single-sided foil, make sure that you place the shiny side downward, away from the roof. This blocks the heat radiation into your ceiling better than when it is facing upward.

You will want optimum attic ventilation. The best way to ensure this is to install a continuous-ridge vent with an external baffle along with a continuous double-louvered soffit vent. You can find continuous-ridge and soffit vents, complete with installation instructions, at a well-stocked home center or lumberyard.

The roof-ridge vent is made of honeycomb plastic material, nailed to your roof sheathing and covered with shingles. Since these vents are only a couple of inches high, when installed they are hardly noticeable from the ground.

Another option is to install a ventilating fan in the attic to help release trapped heat through the existing vents. White or light-colored roofing materials, which reflect rather than absorb the sun's rays, help minimize heat transfer. Consider this when it comes time to install new roofing materials.

Write to Here's How, Copley News Service, P.O. Box 120190, San Diego, Calif. 92112-0190, or e-mail copleysd@copleynews. com. Only questions of general interest can be answered.