DEAR SAM: Our 49-year-old house has metal casement windows which open outward. We have screens for most windows, but we need storm windows for replacements during the winter and also storm windows for the stationary windows. I would like to know where I could buy them.

ANSWER: Although many of the metal casement manufacturers of residential windows have gone out of business, storm windows are still available. Check the Yellow Pages under Windows and you will find several companies which will make them up for you. Be sure that they include attached rubber (or vinyl) gaskets which will fit snug against the metal windows.

DEAR SAM: I live in a development of varied styled ranches, constructed of brick and frame. Almost without exceptional, all of us are plagued with heavy condensation on our windows when the force hot-air furnances are turned on. The problem is so severe in some homes that towels have to be kept on the sills to keep the water from running down the walls and onto the carpets; in others, the paint on the wood-work and the wood-sash shows deterioration. These windows are fitted with aluminum, triple-track been screen windows that have been caulked. Are our homes are too tightly sealed? What can be done to eliminate some of the moisture?

ANSWER: Since the "heavy condensation" is a common problem in so many of the homes, the developer should have been alerted and made responsible for remedial action.

I hardly can attribute the cause to excessive insulation of the walls and ceilings. The wood-sash windows, too, are considered good; the aluminum storm windows appear standard. The furnace, which may have a humidifier attachment. Ordinarily, this humidifier is intended to moisturize the dry air of the furnace as it is subsequently propelled by the fan to the living quarters. This condition provides better humidity through the central heating system and requires no additional room humidifiers for good, normal temperatures.

You should be able to adjust the furnace humidity control to a normal range.

DEAR SAM: Our attic has blanket type, mineral wool, insulation installed between the joists in the attic floor. This insulation does not have any type of vapor barrier - foil, paper, plastic or the like. It seems to have been installed recently as it is approximately 4 to 5 inches thick. My questions are: Should I remove this insulation and install a thin blanket type with a vapor barrier and then replace the unfaced insulation on top? Or should I install additional insulation, with a vapor barrier, on the attic ceiling (roof joists)?

ANSWER: The accepted procedure for attic insulation is that the vapor barrier face the living quarters. The purpose is to prevent any moisture penetration into the insulation and cause a deterioration.

Although you specify that there is no attached vapor barrier, it is possible that a separate vapor barrier exists. This could be in the form of strips of slater's felt, orange paper or plastic which could have been applied during building to the upper side of the ceiling gypsum board. Did you know that some gypsom board has an attached aluminum foil? This would definitely obviate the need of an additional vapor barrier.

Since the insulation appears to have been installed recently, no qualified applicator would have omitted it. Also, check again whether some form of vapor barrier exists under it. If you do not have the know-how of recognizing a vapor barrier, call upon a friend or an expert.

Since 4 to 5 inches of insulation for the attic are not fully sufficient, you should obtain estimates for adding another four inches (with vapor barrier). Instead of applying this on top, it would preferable to install it under the existing one.

For the roof rafters, I would recommend the double-faced, 36-inche aluminum foil rolls, stapled easily at minimal cost. Don't cover any roof and wall louvers, since these should be open at all times.

Samuel Fishlyn welcomes your letters on home improvements and will include as many as possible in this column, which will have a general interest to the readers. Write to him at P.O. Box 62, Newton Centre, Mass. 02159. For a personal reply, be sure to include a self-addressed, stamped envelope.