By J.D. GREWELL

OVER THE PAST DECADE I have evaluated thousands of homes for prospective purchasers in the Washington metropolitan area and on the East Coast. I have seen beautifully designed and seemingly well-built houses hide thousands of dollars in needed repairs. A vast majority of these repair bills resulted because routine maintenance wasn't performed or wasn't done properly. From inattention, faulty repair, or improper installation, the purchaser now has a lot of repairs to make. Moreover, with a depressed housing market, and the cost of home repair professionals going higher every day, many people are tending to fix or improve what they have rather than buying new or paying someone to fix it. All this has made home maintenance a new major U.S. industry. The "do-it- yourself," home manual book trade is flourishing.

Most of the books give good sound advice and one should be in every homeowner's library. I have always been much impressed with the very useful information included in How Things Work in Your Home (And What to Do When They Don't) first published by Time-Life in the mid '70s ($16.95, mail order). This volume provides clear explanations and excellent illustrations. It focuses primarily on items homeowners can safely do themselves with a minimum of tools--routine plumbing and electrical repairs, and simple home improvements. It cautions the reader when a repair is too complex and should be done by a professional, and it pays particular attention to safety issues, but most important, the book's instructions are easy to follow and thorough. Everyone should have a copy around. It is the best single volume on general home maintenance I've seen.

The Reader's Digest Home Improvement Manual, ($19.95), and The Homeowners Complete Manual of Repair and Improvements, by Allen D. Gragdon ($19.95) are solid texts with good information though both are a little weak in some areas. The Reader's Digest book is worthwhile for anyone contemplating purchasing a house since it describes many of the different styles in home design and their drawbacks. As a general reference book, it is very good, but it isn't specific enough if you are looking for instructions on making repairs yourself. A "complete" book rarely provides sufficient detail on repair methods and safety, nor can it adequately cover all areas requiring maintenance. Bragdon's book is superior in both these regards since he devotes more text and space to clear illustrations. He also describes the tools needed for various chores. The cartoons with Practical Pete, a "perpetual victim of Murphy's law," are especially useful for they help the reader to "avoid the kinds of mistakes most amateur do-it- yourselfers make" in the area of safety. Interestingly, this book was the only text reviewed that had a published disclaimer in case someone misinterprets the written guides.

Mass serializaton of books on home maintenance and repair has been a recent trend. We now have series from several publishers including Time-Life Books (45 volumes), Creative Homeowner Press, McGraw-Hill, and Family Guidebooks. The latter three are available in paperback while Time-Life issues the hard-bound copies first and then reproduces only the best-selling titles in paperback.

Compared to the "complete" books, the volumes in all the series are more clearly illustrated and their texts very detailed and specific. But houses and their systems are extremely varied. Which books in a series are the better purchase for your needs? Let's take a common homeowner problem as an example.

Shortly after new shingles have been installed on the roof, it rains and a leak develops on the ceiling next to the fireplace. The homeowner is perplexed when he calls the roofer back and is informed the source of the problem isn't the shingles but the flashing around the fireplace. Of course the roofer says the flashing didn't get fixed because that wasn't in the contract.

The problem is that too frequently homeowners pay for roofing work and are not aware that the metal flashings around the fireplace chimney should be examined and repaired at the same time. There's a reason for this: on well-built homes predating the 1970s, metal flashings were installed by the masons. The flashings actually penetrated into the brickwork to form a watertight bond which only required minor caulking every few years to keep them that way. Since the 1970s, however, masons generally have no longer installed the flashings: they complete the chimney and the flashings are nailed onto the chimney by the roofers, then heavily caulked to create the watertight seal. Caulking easily dries and cracks from exposure to sunlight, heat, and weathering, and requires frequent resealing. Had the homeowner had any good roofing guide he would have been more informed and could have requested reflashing as part of the roofing contract. Keep in mind too that this hypothetical homeowner only had to deal with a minor leak. Had there been a heavy snow melt, for example, he could have lost the ceiling and his furnishings as well.

The Guide to Roof and Gutter Installation and Repair ($3.95) in the McGraw Hill series, which has "caution" and "warning" notices throughout all its volumes, makes a point of cautioning homeowners always to reflash the chimney if resurfacing the roof and not to damage the flashings when removing them, since a pattern is needed for their replacement. Time-Life's volume, Roof and Siding ($13.95) is more clearly illustrated, given the same task of flashing a chimney, but does not offer boldly printed cautions and lacks the advice to keep the original flashings for a pattern. The Creative Homeowner Press on the same subject in Modern Roofing Care and Repair ($6.95) by Donald L. Meyers, is by far the best of all the volumes. Meyers starts his explanation with "chimney flashing application is complicated." He then takes you step by step through most chimney and roof designs, and includes the art of setting flashings into the masonry which is a far superior method.

Another important yet usually simple maintenance chore is servicing portions of forced air heating and cooling systems. The volume of air passing through the fan chamber is closely calculated by heating, ventilation, and air-conditioning engineers. Before the energy crises when energy costs were relatively low, the engineers designed systems with a 20 percent error rate. Today, the error rate is often less then 5 percent. Central plants used to be as much as 50 percent oversized to assure heat under all weather and care factors, since their design rendered them inefficient. If the volume of air is greatly reduced by a blocked filter, or if the motor begins to drag because of dirt or a loose fan belt, the passage of air will be insufficent to prevent overheating of the heat exchanger on both new and older systems. If the heat exchanger goes on an old system, chances are the entire furnace will need replacing.

The text from Creative Homeowner Press called Heating, Cooling, Ventilation by Jay Hedden ($6.95) recommends vacuuming the fan motor and blades and lubricating the motor bearings. Hedden warns "do not overdo this lubrication; if the instructions say two or three drops of oil, do not apply four or five." He does not say, however, to use middle weight non- detergent electric motor oil instead of light machine oils like "3 in 1"--a common mistake people make.

Time-Life's volume, Heating and Cooling ($13.95) does refer to the proper types of lubricants but recommends more than most manufacturers call for--"dribble six to eight drops . . . into each cup." It also calls for keeping the filters, fan blades, and motors cleaned. Importantly, it says to shut the power off when working on the system--this is mandatory to prevent accidental electrical shock. Both these volumes tend to be somewhat simplistic on specifics but this is aysdue to the vast number of heating and cooling systems currently available for purchase.

Picking and choosing specific topics doesn't do any of these volumes full justice. I personally recommend you compare several for yourself using the maintenance tests you feel comfortable with. Use these texts for their intended purpose--to provide enough information and advice to make you an informed consumer. Dollar for dollar, though, the Creative Homeowners Press series is, as a whole, far superior in its "how to" instructions--if you pay attention and can understand the details.

Meanwhile, keep in mind that the other day when my 12-year-old washing machine gave out in the middle of a load of baby clothes, I still couldn't find a book detailed enough to tell me how to replace the drive belt. The books did get me inside the machine, and I did find out it was the drive belt that was broken. The books also advised me to get the model number of the machine and the drive belt part number before calling the repairman. When the repairman came out he had the part and it only cost me $49. So just having a few good books on the subject can save you time and money even if you don't do it yourself.