DEAR BOB: I own 41/2 acres of land, worth about $4,400 on which I want to build a two-bedroom home. While I earn about $20,000 per year, I have no appreciable savings, could I realistically hope to borrow money to build the house? Charles Y., Washington.

DEAR CHARLES: Yes, Your bank or savings association wil be glad to finance your new home's construction. If you plan to build the house with your own labor, and not hire a general contractor, however, you'll find many lenders won't make such loans. The reason is do-it-yourself builders often make costly mistakes and lenders want no surprises. Talk with loan officers at several mortgage lending insitutions, as you'll find that terms and interest rates can vary widely. It pays to shop for home construction mortgage money.

DEAR BOB: In a recent column you said that a homeowner in a 25 percent income tax bracket will save about 25 percent of his mortgage interest and property tax payments in income tax dollars due to the tax deduction. For a taxpayer in a 50 percent tax bracket, would that mean a 50 percent savings? Mr. and Mrs. A. S., Chevy Chase.

DEAR MR AND MRS. A.s.: Yes. For a taxpayer in a 50 percent income tax bracket, for every $1 of itemized income tax deductions, he will avoid paying about 50 cents in income tax. That means a taxpayer in a 50 percent bracket who has $1,000 of itemized deductions will save about $500 in income tax dollars. In other words, high tax bracket taxpayers save more tax dollars from itemized deductions than do taxpayers in lower tax brackets.

DEAR BOB: My parents, age 68 and 63, own their home free and clear. Except for Social Security, they will have no retirement income. I'm worried that if their health should deteriorate, they might become unable to pay their bill and could lose their home. Should they put this house in my and my sister's names now? Nicholas M., Mt. Pleasant, Va.

DEAR NICHOLAS: No, A free-and-clear home can mean retirement security. If your parents run short of money, they can mortgage the home or sell it to raise cash. An installment sale could provide secure income for the rest of their lives if they should wish to sell and move elsewhere. Your parents are better off than you think they are.

DEAR BOB: What is the best way to aviod buying run-down property and then finding out that remodeling it will be too costly? Marion W., Washington

DEAR MARION: There are several ways. One is to make your purchase offer to the seller, but include a contingency clause such as "this offer contingent upon buyer obtaining, within 10 working days, satisfactory bids to remodel the property." Another is to pay the property seller for a 30-day purchase option to give you time to obtain remodeling bids. Be sure the option gives you access to the property so contractors can inspect it to make their remodeling cost estimates.

DEAR BOB: We own some summer property in northern Minnesota that we plan to sell next summer. The realty agent in the area wants a 12-month exclusive listing if he is to work on our sale. My son, who is taking a college real estate course, says that's too long. What do you think? Ted R., Chevy Chase.

DEAR JED: I think you've got a smart son. While sales of summer or seasonal vacation properties usually take much longer than do traditional single-family homes, a 12-month listing is too long. A six-month listing should give the agent sufficient time to properly market the property.