For remodeling, this year may be easiest on your pocketbook

If you've been sitting on the sidelines, holding off on upgrading the house for more promising economic days ahead, there are several reasons why this year may be the right time to build on or remodel.

Contractors, for example, are far more competitive on bids, material costs are stable or falling in many parts of the United States and credit for a $20, 000 remodeling project is easier to swing than $70,000 or more for a new house.

''An owner of a structurally sound home probably can get more housing value for his dollar now by remodeling than by building new,'' asserts Stan Woodman, a national home and remodeling designer.

''An efficient, well-planned improvement project can add value to the entire home because older homes are worth relatively more, compared with new construction, during periods such as this when fewer new houses are being built.''

In the last two years, Mr. Woodman has done relatively more remodeling design , primarily because people don't have the money to spend for new construction.

Too, the building slowdown has hit contractors hard. In most regions of the country, contractors now bid tighter on the labor fraction of a job than they would two years ago.

''We're bidding at least 10 percent under what we would bid in more normal times,'' says an Ohio remodeling contractor. ''We're hungry. I have a lot of subcontractors calling me to bid on jobs. Three years ago I had to go after them.''

The cost of materials are stable or falling in most areas. You may not notice much change in list prices, but suppliers are pinched by the slowdown as well as the consumer. Most will haggle to some extent.

''My suppliers are more anxious to bargain on price than they were just a year ago,'' declares Ron Cridelar, a kitchen-and-bath contractor. ''One problem is that many suppliers have let inventories run low. That means delays while they order materials.''

If you own a comfortable equity in your home, you are probably in a favored position with lenders. While mortgage interest rates are fairly inflexible right now, contractors often can help line up financing for a job. Make sure you check it out thoroughly, however, and get the best terms available for your purse and protection for the future. Ask questions.

In some areas where lenders are still in the market, federal mortgage-guarantee programs, such as the Federal Housing Administration and Veterans Administration, are below mandated limits.

If interest rates drop much by late spring, the building slump could be over quickly, but the outlook is uncertain at best. Economists disagree on what that magic percentage figure would be; somewhat below 14 percent on mortgage loans, probably.

''We know there's a lot of deferred housing demand out there,'' Woodman says. ''We have not begun to build the houses we needed in the past four or five years.''

Woodman notes that sales of his stock plans and design books are up sharply in the first weeks of 1982.

''Our custom design business has been down woefully for the past two years,'' he reports. ''Now it's up by several hundred percent just in the past two or three months. That indicates to me that there's a great deal of interest and optimism among people planning to remodel or build.''

Much of his increased business has come from the oil-rich ''sun-belt'' regions of Oklahoma, Texas, and Colorado which have remained relatively prosperous and fully employed during the past few months.

''But I'm optimistic about the home-construction picture in general,'' he says. ''And when building opens up again, subcontractors will be busy with new construction. That's why I believe now is the time to remodel or add on;, or at least get past the planning stage so you're ready to start quickly once you decide to go.''

The current building slump started more than three years ago, triggered first by rapidly rising material costs and then aggravated by excessively high interest rates.

Inflation has built up a three-year-old head of steam under that economic lid. Once the building industry gets back on its feet, labor and material costs may start climbing rapidly.

If you do plan home-improvement remodeling this year, take a hard look at energy-conserving features that qualify for income-tax credits. Items still eligible for federal tax credit include: insulation for ceilings, walls, floors, and water heaters; storm or thermal-pane windows; automatic set-back thermostats; and most solar-energy systems.

To qualify for tax credits, these features must be completed before Jan. 1, 1986, and have a useful life expectancy of at least three years.

Energy-saving improvements earn a credit of 15 percent of their cost on the first $2,000 spent. Remember, this credit is a dollar-for-dollar reduction in the amount of taxes due rather than a deduction on taxable income.

In addition to the federal energy tax credit, 46 of the 50 states and many local governments also allow credits for certain items against income or property taxes.

While it may be too early to start talking about a wide-scale revival in the construction industry, this year could be the time to complete that remodeling job you've been planning.

It could save you money in the long run.