THE WAY Cally Irish tells it, the first time architect Harry Montague looked at the back of her house, he laughed for 10 minutes.

Montague tells it a little differently. He said when he saw the successive lowers and tiers of the house owned by Leon and Cally Irish - a wonderfully romantic fantasy of a house typical of other great Cleveland Park residences - he decided it was a wedding cake and the only thing to do was to make a plate for it.

Montague's cake plate, a giant curve works as a deck off the Irishes' kitchen and family room, which had been sun porches. A sweeping staircase from the deck units the house and the yard, not an easy trick on the steep hillside lots of Cleveland Park where the backs of the main floors of many houses sit at least a tall story above the ground. Bringing the outside in on such houses is more like bringing the outside up.

"The deck is like a giant outdoorplaypen," said Cally Irish. "We have four children - two classic pairs, 9 and 10 and 1 and 2. Like most children, they like to stay close to the kitchen. Since both the kitchen and the family room open onto the deck, it works like a charm."

Underneath the deck is covered storage space for all the gear that most people seldom have a place for - the sled, the baby buggy, the wood for the winter, the trash barrel adn other unglamorous necessities of life. Some harried homeowners might be inclined to say that the below-deck space is as useful as the deck itself.

One architectural question that could be raised is why the deck and staircase have solid, rather heavy-looking sides. Montague says he felt the deck had to look sturdy and heavy to seem sufficient to support the three stories on top. For another, the solid sides screen decksitters from the neighbors.

The deck is by no means all that happened to the rear of the Irishes' house. The kitchen, which started life as two little rooms, has become what can only be called banquet-sized. Cally Irish is fabled in her neighborhood for her adventures in food, so much so that there is a steady stream of people standing on the other side of the central counter watching while she makes ice cream or cans tomatoes or bakes bread or stirs up marmalade. The kitchen, as a result, was designed for large audiences and loud applause.

The central counter is one of the marvels of the kitchen. Montague said Cally Irish at first scared him when she started telling him all the things she intended to hang on a pot rack she wanted suspended from the ceiling. "I thought the ceiling would come down and pull the house with it if we put all that on it," Montague said.

Instead, he designed a long counter - one side of it a cabinet, the other a bookcase - topped with a chopping block surface. From this rise two 4-inch steel Lally columns with a rectangular frame of 3-by-4 angles welded on with iron hooks from which to hang pots, pans, choppers, colanders, fruit baskets and anything else Cally Irish can buy or make. It looks sturdy enough to support the stove if the need arose.

Most of the eye-level storage is in open shelves. An area adjacent to the dining room serves as a bar or butler's pantry.

Cally Irish had wanted a restaurant-sized stove ever since she first played with a toy one, and she got her wish. THe gas stove is enormous, and Montague didn't so much make a place for it as enthrone it. The big black stove with its red trim is ensconced in a niche topped with an arch. Over the arch is a shelf that holds the fan and built-in lights.The door and drawer handles on the solid oak cabinets also are semicircles, cut especially for Montague by the Woodmode factory (bought through Kitchen Guild).

The floors and the sink counter top are all Mexican tile, unfinished, unglazed, which is the cheapest going. It was bought as $1.20 a square foot but it's now at least 25 cents more. They have a strong, warm look that goes well with four childre, a dog, a cat and doing your own canning.

"The kitchen is everything I love," said Cally Irish. "I have a study upstairs but always go down to the kitchen to work, even to write letters."

At the end of the kitchen is a round Knoll Saarinen table with bentwood chairs. It looks out on the deck through sliding-glass doors. Best of all, the whole end is topped with another Montague motif - an arched skylight, about 4 feet wide and 8 feet long. The effect might be called a heaven dome.

The family room next to the kitchen has a sturdy-looking stone fireplace that was installed at the same time the other work on the house was done about three years ago. "We had intended the room as sort of an adult living room. But it didn't work like that at all because the children all want to be near the kitchen. It's always confused with toys and such. So I just went out to Pier One or Dockside or somewhere and bought good, comfortable, sturdy furniture. The great thing about this house is that everyone has a place to go, without bothering anyone else."

Leon, a lawyer, and Cally, a teacher who now teaches at home and serves as president of the National Child Research Center, bought the house 7 1/2 years ago. "We went to see it eight times before I could get up enough courage to buy it," said Cally Irish. "I said, 'Who on earth would design a house like this?'" The house was built in 1912.

The remodeling, which included a great deal of unexpected repairs on rotten wood and elextrical and plumbing work, amounted to about $57,000, according to Montague.

The nearby house of Cheryl and Norton Tennille is a Cleveland park wedding cake as well. The Tennilles (she is an environmental researcher, he is a lawyer) bought theirs about two years ago. They thought then they had a great buy at $175,000; today, the median price for a Cleveland Park house is $206,000.

They found the house, built in 1896, through what has vbeen called "the Cleveland park real estate league" - by which most of the best Cleveland park houses never hit the market. In other words, friends of the owners told them the house might be for sale. So the Tennilles stood by, check in hand. They loved the house, they had driven by it for six years while taking their three children, now 5, 8 and 10, to school.

"We were really awed by all that space," Cheryl Tennille said. But soon after they moved in, they found all that space needed a fair amount of work: insulation, new storm windows all around, new dry walls atop the old plaster and some new disignwork by architect Dickson Carroll, who llives nearby! They have big plans for more.

So far, Carroll has eliminated all the extra doors the Victorians thought necessary. It seemed at first that every room had umpteen doors. The Tennilles installed dry wall over the most inconvenient ones and installed storage behind some others.

They also took out two closets and a bath to make one grand bath, which even has a plant shelf. Most of the work was done by Unity Contractors, who the Tennilles said, "moved in with us practically from January to June." ANdy Knapp has also been a big help with painting and carpentry. The Tennilles decided to do their own landscaping (though the house was once famous for its garden) after a bid came in at $1,000.

The tennilles especially enjoy the house's magnificant porch with its circular cantilevers and portico. "A porch gives you an entirely different stle of life," Cheryl Tennille said."You can see people so casually, without any planning. And the children can be under eye but not under foot. That's the great thing about Cleveland Park. The day we moved in, the children whooshed out of the house as though they were sucked out by the vacuum cleaner."

Seven Cleveland Park houses, including those of the Irishes, the Tennilles and the Gary Knopffs, John Steadmans, Richard Jorgensons, Charlotte Jackson, and Jeremiah Lambert, will be open for tour today from 11 a.m. to 5 p.m. Tickets ($7) are on sale at the National Children's Research Center, 3209 Highland Pl. The proceeds benefit the center, a nursery school.