Trouble with can lighting is the older fixtures do not provide an air tight seal from attic space to conditioned space. With this being an important factor in both indoor air quality and energy efficiency retro fit work is recommended if the fixtures are easily accessible. The older recessed light fixtures require a 3" clearance from combustible materials; unless marked IC rated fixtures(Insulation Contact). If the fixtures are IC ratedic rating simply sealing them off with expansion foam is recommended. You can verify the fixture rating by the label inside the fixture (remove bulb) or from the attic space most manufactures have it also stamped on the fixture itself. Notice on the sample image top right corner the fixture is labeled TYPE-IC. If you can not confirm the rating it is safe to assume it is not.
Save an average of up to 25% on your energy bill; Find out which improvements to make - the report will estimate the savings and costs of each potential upgrade; Increase the comfort of your home - no drafts, better temperature control; Increase the value of your home - each dollar spent on recommended improvements will increase the future sales value by more than a dollar.