When most people buy a house, they tend to focus on the here and now — what it looks like and all the good times they will have living there. To the extent that they think about resale at all, the conversation centers on the features that may attract future buyers.

The real key to resale, though, is how well the owners maintain the house, but this issue generally draws little interest at the time of purchase and often falls off the radar screen soon after move-in.

In fact, “the ability to ignore the exterior of one’s house is nearly universal,” said J.D. Grewell, a Silver Spring-based private home inspector for nearly 40 years who has conducted more than 14,000 resale home inspections.

He attributes this blind spot to the current lifestyle.

These days, especially with central air conditioning making the interior much more inviting than the back yard during the summer, few people spend much time outside taking a good look at their home’s condition. Regular weekend mowing was one way owners used to keep track of the exterior situation, but now, many homeowners hire a lawn service to do the mowing, he said.

Grewell also lamented a decline in shop classes in high school, which once exposed all the boys and some of the girls to the basics of working with tools and doing maintenance.

“This has robbed an entire generation of the skills needed to make simple home repairs correctly,” he said. “If a light switch stops working, they plug in more lamps, run a lot of extension cords or feel their way around in the dark.”

But, Grewell emphasized, the most important maintenance tasks are not that onerous or time-consuming, nor is a vast knowledge of building science required. His “must-do” list is short, with only five items:

●Change the air filter of your central heating and air conditioning system every other month.

●Clean the gutters two or three times a year, depending on how many trees you have.

●Paint the exterior every three to 10 to 15 years, depending on which materials are on your home’s exterior.

●Caulk the exterior every three to five years.

●Pay a professional technician to do an annual safety check of your heating and cooling system.

It’s possible to finesse most of the exterior chores if you have materials that require little care, an option for owners building a custom home or a major addition because they will be selecting everything that goes into the house. Nonetheless, this option is rarely taken, said Washington architect Thomas Manion. More often, the homeowners opt for lower-priced, high-maintenance materials so they can afford expensive interior finishes.

But while using untreated wood for exterior trim will save a few thousand dollars initially, it carries the added cost of regular repainting.

“The client will say, ‘With the money I saved here, I can afford to get crown molding throughout my first floor. I can see that, and my family and friends can see that. No one will notice the outside trim,’ ” Manion said.

So when resale time finally rolls around, how does conscientious maintenance — or the lack of it — affect the bottom line?

Allan Washak, a Howard County homebuilder-turned-real estate agent, said that doing nothing for years and then making a massive effort to woo buyers can cost you thousands. For example, he said, the cost to belatedly fix exterior trim could be twice as much as what it would have been had the owner tended to the painting and caulking all along.

He has seen owners of a large, 12-year-old brick house in the $1.3 million price range spend $15,000 to $20,000 to replace the rotted wood exterior trim with “nearly foolproof” plastic trim to satisfy their real estate agent. Had they’d maintained the trim on a regular schedule, their total cost for its upkeep would have been far less, about $6,000 to $10,000, he said.

In the $500,000 price range in Howard County — for a 2,500-square-foot house), Washak said that the owners can have the same issues with exterior trim but that they likely wouldn’t have the cash to address it, so they would have to accept a lower sale price.

Katherine Salant has an architecture degree from Harvard. A native Washingtonian, she grew up in Fairfax County and now lives in Michigan. If you have questions or would like to suggest topics for coverage, contact her by e-mail or at katherinesalant.com .