Many homes and apartments have living-dining areas that run together or that are separated only by a waist-high divider such as a low counter or wall. Others have dining areas that are part of the kitchen, set off a little in a separate alcove or divided from the main part of the kitchen by a low counter or storage unit.

Often a little more separation would be welcome, either for privacy or to conceal one room from the other (for example, when a sink is loaded with dishes or when the hostess wants the table set up before company arrives without it being visible to everyone who enters).

Another instance where a divider is desirable is in those homes or apartments where there is no real entrance hall or foyer to separate this area from a family room or dining room as people enter. This may not be objectionable under norman circumstances, but it may be inconvenient when a visual barrier is desired between the foyer area and the rest of the house, especially if children are playing in the family room or den and things are not as neat as the parents would wish them to be.

There are easy yet decorative ways to solve problems of this kind without undertaking major alterations or construction and without interfering with air conditioning or heating by obstructing air flow. Using aluminum blinds with slats only 1 inch wide, the room divider actually can be a series of blinds hung in a specially constructed wood framework that rests on top of a waist-high wall or partition (or on top of some low cabinets or storage units that are strategically positioned to serve as the base for such a divider).

When the blinds are closed there is complete privacy, and no one can see from one side to the other. When the blinds are open there is virtually no obstruction to vision or light, or to the flow of air and heat from one room to the other. And for those occasions when the original "open" feeling is desired, the blinds can be raised completely so that only the open framework of painted or stained wood remains.

Where there is no divider between rooms, a partition wall first can be constructedd, using 2-inch by 3-inch lumber to frame it out. Then both sides may be covered with gypsum board painted to match the rest of the walls. Prefinished wood paneling also could be used to cover the partition. Instead of building a permanent partition one also could by a couple of low bookcases or storage units and joint them to form a low divider wall or partition on top of which the framework for the blinds could rest.

Aluminum blinds may be made to order by the dealer, so the framework into which the blinds will fit can be any convenient size. Sizes can be varied to fit individual needs. Prices for these blinds will, of course, vary with the size, but as an indication of approximate cost, a blind measuring 24 inches by 36 inches costs about $42, and one measuring 36 inches by 76 inches about $80.

To make sure the blinds will fit properly it is best to construct the framework first, then measure the openings to be certain the blinds will fit properly between the uprights.

The header that goes across the top is a piece of 2-inch-by-4-inch that is fastened to the ceiling by nailing it into the beams. If you cannot find solid wood to nail into (above the plaster), use plastic expansion anchors set into holes drilled in the ceiling. Then use wood screws that go through holes drilled in the header to secure it.

It is important to position this accurately over the center of the low partition wall or divider: Use a plumb line (a length of string with a plumb bob or similar weight at the end) to line up the 2-inch-by-4-inch header in such a way thawt a line drawn length-wise through the center of it will be directly over the center of the divider wall below it.

When the header has been fastened in place against the ceiling, nail the 1-inch-by-6-inch sill piece to the top of the divider wall to act as the bottom of the framework, again centering this directly under the center of the overhead header piece. This sill piece should overlap the partition wall or divider on both sides and for a neat finished appearance also should protrude at the end slightly.

The next step is installing the vertical 4-inch-by-4-inch posts that frame each end of the unit (you could use 2-inch-by-4-inch, but 4-inch-by-4-inch end post will look better and will be less likely to warp with time). Each post should be measured separately for a snug fit between the header and sill, then each should be secured by toenailing.

Before nailing, use a spirit level to make sure each end post is perfectly plumb (vertical), checking at least two adjoining sides to make sure it is plumb in both directions (from side to side and from front to back). To keep the end of the post from slipping when toenailing, drill a small pilot hole into the 4-inch-by-4-inch at the proper angle, then press a block of wood behind the post to act as a brace while nailing (if you can get an assistant to hold this block for you, so much the better).

Now you can install the vertical 2-inch-by-4-inch dividers that separate the individual blinds, spacing them so there will be the same width blind between each post. These 2-inch-by-4-inch also should be cut invidually (in case ceiling heights vary slightly), then checked with a spirit level to make sure they are plumb before toenailing to the header at the top and the sill piece at the bottom.

All nails should be countersunk slightly to recess the heads below the surface, then the holes that remain should be filled with wood plastic or putty in order not to show after the framework is painted. Generally speaking, painting or finiishing will be easier if this is done before the blinds are installed.

Since the blinds are fully assembled and the special mounting brackets are finished, installing them is comparatively simple. The supporting brackets are secured with screws driven up into the header piece, positioning each bracket slightly in from the front edge of the wood. The narrow 1-inch header piece on the top of each aluminum blind then can be snapped into the bracket and none of the blind's operating mechanism will be visible when it is hung.