DEAR SAM: The blacktop driveway to our garage is seven years old, in need of rebuilding this spring. Frost heaves have produced eruptions in which we found stones the size of candle-pin bowling balls. This winter following the freeze, snow storm and heavy rains, whole sections of the driveway were elevated. There were apparently no large stones under the new heaves. One contractor suggested preparing the bed of the driveway with a new base of at least one foot of good gravel or crushed stone; another suggested a drywell under the driveway proper. What do you recommended?

ANSWER: The specifications - "at least one foot of gravel or crushed stone" - would undoubtedly make an excellent base, not only for a driveway but for a highway. The snows storm and the heavy rains of January, 1977, could hardly be contained in the proposed "drywell." No reference is made by either contractor concerning the thickness of paving.

I don't think it necessary to have such stringent specifications. In removing the existence blacktop, your contractor will check the undersoil for any peat, loam or vegetation, or protruding large stones, all of which will be replaced with two inches of crushed stone base.

Paving should consist of two inches of bituminous concrete, applied in two courses, with a slight elliptical pitch so that rainwater will run off at both sides.

If your driveway has a sloping grade, be sure that the garage floor will not be adversely affected: the pitch should be away from the garage.

Since the blacktop is porous, you may decide that a sealer is desirable; however this need not be included immediately and when applied several months later, it should be compatible with either the tar or asphalt of the blacktop. (Stickiness will result if incompatible.) Estimates for the work should be obtained from at least two contractors, experienced in driveway construction, who will agree to include a limited warranty of satisfaction.

DEAR SAM: Last fall, my patio with a fibreglass roof was enclosed, which was intended for use as an extra bedroom. After moving the furniture into it, I noticed a week later that the furniture and floor were soaking wet and beads of condensation were attached to the underside of the fibreglass panels. How can this problem be corrected? Would another layer of fibreglass with an air space in between eliminates the sweating? My wife wants to retain the transparent fibreglass if at all possible.

ANSWER: Sorry, but unless the patio is on the southern side, its present construction is hardly suitable for a comfortable bedroom. Even with an "insulating second layer" of fibreglass panels and a "dead air space," the expansiveness of the sizable ceiling is beyond the prerequisites for achieving adequate heating.

What have you used for insulating the walls of the new room? Are there several windows therein? And how does the floor, if concrete, stand up against the winter season? A fibre padddling and wall-to-wall carpeting are still unequal to the task of a warm floor.

The elevation of the floor at least four inches, formed by 2 x 4s at 16 inches on center and 5/8-inch plyscore, throughout which a full-thick blanket of mineral wool insulation is installed, would render it satisfactory. Also, you will need heating!

I don't believe that you or your wife can use this area for an extra bedroom in the winter unless it is completely rebuilt as a room with insulated walls, ceiling, floor and heating. Let it suffice, as is, for spring and summer use.