ST. PETERSBURG — In the 1950s, before air conditioning came into widespread use, the new Vision-Aire homes at the tip of the Pinellas peninsula were designed ''by Florida itself.''

To take advantage of the semi-tropical setting near Tampa Bay, all living areas faced the prevailing southeast breezes. Wide overhangs provided protection from sun and rain. Concrete walls were replaced by glass and wood jalousies, adjustable to suit weather conditions and ventilation needs.

"Don't fight Florida's climate!'' urged the sales brochures. "Take the good things Florida offers.''

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A dozen of the houses were built along 69th Avenue S and on Pinellas Point Drive. Over time, the Vision-aire name faded in use, and they came to be known as the "bird cage houses'' because of their airy design.

Eleven houses have survived, and now some of the current owners hope to have them designated historic landmarks so their distinctive looks won't be altered beyond recognition.

"The reason we want to do it is that they are unique houses,'' says Ananda Kelley, a bridge engineer who has owned a bird cage home since 2013. "They are really cool and it's important to us they are preserved.''

Kelley and others seeking landmark status for their homes are in the process of submitting applications to the city that will include descriptions of the houses and their historic significance. The owners are working with St. Petersburg Preservation, which will be the beneficiary of a fund-raising "porch party'' Feb. 7 that will include tours of at least two of the houses.

It was architect George Leonard Ely who designed what were to be 95 Vision-aire homes in a new community called Bay Vista Park at the southern end of Fourth Street. He worked with another modernist architect, Glenn Q. Johnson, who went on to design the St. Pete Beach Library, the North Shore Aquatic Center, the Pinellas County Judicial Building and several area schools.

Though the floor plans varied, all of the houses were a split-level style with the main living areas high enough above ground that the air would be 10 to 12 degrees cooler. Roofs were made of 3½-inch inch tongue-and-groove cedar, "nature's best insulation.'' Built-in closets and cabinets were kept off floor level for ease of cleaning and to allow "passage of cool air.''

In keeping with the minimalist style, there was minimal upkeep and maintenance — no paint, no plaster.

Outside, "every Vision-aire house is carefully and appropriately landscaped, using proper tropical plants, flowers, shrubs and trees,'' the brochure said. "Frozen gravel is a practical substitute for large areas of grass, which involve maintenance, considerable expense and labor.''

Just one of the houses is currently for sale, that owned by accountant Gerry Broughman.

Broughman had redone two bungalows in Historic Kenwood but often visited a friend who lived in a bird cage home. "I fell in love with the style,'' he says, so he jumped when one came on the market.

A previous owner had replaced the original cedar roof with a metal one. Another owner had enclosed most of the open areas, added vinyl siding and gutted the interior before losing the house to foreclosure. Broughman got it from the bank in 2009 for $55,800.

"I bought basically a wreck for land value,'' he says.

But the house had great bones and soaring cantilevered ceilings. Broughman found a copy of the April 1956 issue of Living for Young Homemakers, which featured a bird cage house in Crystal River on the cover that was nearly identical to his. He used that as a guide as he began a major renovation and restoration.

"The city was great,'' Broughman said of St. Petersburg building officials. "With a place like this, they could have made it hell but they didn't.''

On the ground level, which already had a bedroom and bathroom, he enclosed a carport to expand the living area and make room for a kitchenette. Otherwise, that level looks much as it did originally with exposed concrete block walls and hard-surface floors.

The house is in a low-risk flood zone, but "if it did get flooded, all the electrical is upstairs so you just take out the baseboards and rinse it out,'' Broughman says.

He got rid of a rickety deck and took off the siding that partially enclosed the two patio levels, which are connected by floating stairs. To comply with current building codes, he removed the patio railings because they had panels spaced far enough apart that a child could fall through. He replaced those with horizontal rails and a metal bar close to the floor to keep a beer bottle from rolling off and hitting someone on the head.

The house originally had jalousie windows — no longer allowed by building codes — so Broughman enclosed the main living area with hurricane resistant windows left by a prior owner. He salvaged vintage St. Charles steel drawer cabinets from another mid-century house to use in the kitchen. New cork flooring replaced the old.

In toto, the renovations ran well over $100,000, "though I stopped keeping track,'' he says. "It's not just the money but all the time I put in.''

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Broughman's next project is a 49-foot, all-wood boat on which he intends to take an "extended cruise,'' as he puts it. It is now up to a longtime friend, real estate agent Eileen Bedinghaus, to sell the house, which is priced at $425,000 and offers a glimpse of Tampa Bay through the trees across the street. A bayfront park is just a block away.

Bedinghaus, a fan of all things mid-century modern, or MCM, has staged the home with '50s era tables, chairs, couches and accessories from The Foundry Furnishings on Burlington Avenue. Even before she put the house on the market, she got an offer from the former treasurer of St. Petersburg Preservation, who now lives in Indiana and flew down expressly to see it. (The offer had contingency so it has not yet been accepted.)

Sarasota has often been touted as Florida's mid-century mecca but Bedinghaus notes that Pinellas County also has a wealth of MCM architecture. A main purpose of the fundraiser for the preservation group, which typically focuses on older buildings in and around downtown, is to draw greater attention to the county's mid-century heritage.

Interest in bird cage houses was so high that the event quickly sold out after a notice went up on Facebook.

"We had 600 people interested,'' Bedinghuas said, "and 200 tickets.

Contact Susan Taylor Martin at smartin@tampabay.com or (727) 893-8642. Follow @susanskate