'Generally, the advice I've read says not to sell because I have a low-interest-rate mortgage'

"If I sold the property now, there wouldn't be any capital-gains tax." (Photo subject is a model.)

Dear Quentin,

I have been thinking about renting out my primary residence and moving into another property I own because of a steep, problematic stairwell. Generally, the advice I've read says not to sell because I have a low-interest-rate mortgage. However, I could rent the property and generate $800 a month in positive cash flow.

I haven't been able to calculate my rate of return because that would require making assumptions about future appreciation. Even so, if I have $300,000 or $400,000 equity tied up in the property, I have to wonder whether that represents a low return on my equity. If I sold the property now, there wouldn't be any capital-gains tax.

How should I think about this given that I'm 80 years old?

Two-Story Resident

You can email The Moneyist with any financial and ethical questions at qfottrell@marketwatch.com. The Moneyist regrets he cannot reply to questions individually.

Related: 'We made a bad, bad decision': I learned the hard way how to manage my aging father's money

The Department of Agriculture's Section 504 Home Repair program offers loans and grants for seniors.

Dear Two-Story,

There's a lot of equity hidden under your stairs.

Your first option: Fix the stairs. Before you sell or become a landlord, get two or three estimates for making the stairwell safer or eliminating the problem altogether. If you can solve the problem for, say, $20,000 or $30,000, that could be a much simpler solution than selling a home with $400,000 in equity or taking on the responsibilities of being a landlord.

You have identified a problem that will probably only get worse as you age and you face more challenges with mobility. Like many seniors who live in homes with more than one story, you have a problem that won't go away by ignoring it. It's all too easy to live with these niggling problems until one day a problem turns into an incident.

Second, if you have $400,000 in equity, and you can afford a smaller home or apartment - and you are OK with the HOA fees and the moving and legal costs - I don't see a problem with you taking the plunge. Your comfort, peace of mind and, last but not least, physical safety are paramount. Having enough money gives you options.

Clearing $800 a month in rent is not a great cash return on your equity.

Your third option is renting out your home for a change of scenery. Being a landlord is work, and you may have a long snag list. I'm on the fence about this option, unless you have either worked out a shorter-term solution and have an emergency fund large enough to fix the stairwell or future-proof your ground floor, or you have another property you can move into.

Clearing $800 a month is not a great cash return on your equity (annual cash flow divided by current equity). On $300,000 of equity, it's 3.2%. On $400,000, it's 2.4%, which is below recent inflation rates. That's assuming the $800 is after your mortgage and ordinary expenses, including taxes and insurance, and accounts for vacant periods or repairs.

That's not your total return because it doesn't include appreciation - or, heaven forbid, depreciation - of your home. The advantage of renting out the home is that you clear a profit, and have the option of moving back into a future-proofed home. You also retain the potential for future appreciation. If you go, think about community and transportation.

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Home grants and loans

There are grants and loans aimed at helping seniors update their homes. The Department of Agriculture's Section 504 Home Repair program offers loans of up to $40,000 at a rate of 1% interest and grants of up to $10,000 for homeowners 62 and over in rural areas whose household income is under 50% of the area median.

Look into the Weatherization Assistance Program and the Low Income Home Energy Assistance Program. Seniors who own their own home can consider getting reverse-mortgage counseling, if only to familiarize themselves with the option. Many states offer grants, low-interest loans and/or assistance to help seniors upgrade and repair their homes.

From a practical perspective, I'm not sure you can make a bad decision, provided you can comfortably afford whichever option you choose. A 2.5% mortgage is certainly worth taking into account if selling means replacing it with a 6.5% mortgage. "Buy low, sell high" goes for home prices, but not necessarily for interest rates.

You have something more valuable than a low mortgage rate.

But a low mortgage rate is only one part of the equation. First, please be cautious about taking on new long-term debt in your 80s if you have sufficient assets to pay cash for home repairs or a move. Happily, you did not mention dipping into your retirement savings or the need to take out a loan, so I'm hoping those options are not on the table.

Enlist a financial adviser who specializes in retirement and senior estate planning, and talk to friends and family about your wish to move. You did not give details about your finances, required minimum distributions, Social Security income, debts, etc., so I don't know how solid (or not) your finances actually are.

I do know that you have something more valuable than a low mortgage rate: the ability to use your equity to make your home safer and life easier. A safe and comfortable home is a luxury you worked hard to achieve. After all, more than one in four adults aged 65 and older experience a fall each year, which can lead to a precipitous decline in their health.

Don't let a bad stairwell scupper your plans.

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-Quentin Fottrell