After a storm destroyed a large tree in the back yard of their Potomac home, Ruth and Phil Suttle decided to fill the empty spot with an elegant garden pavilion. The open-air structure serves as the exclamation point on a romantic, English-style garden featuring shade-tolerant plants, small statuary and a footbridge leading over a stream.

“We wanted to create an area that was under cover,” said Ruth Suttle, an avid gardener. “The pavilion allows us to escape the heat of the summer and gather with friends and family.”

Designed by Bethesda architect Jim Rill, the super-size gazebo is a luxurious model of the outdoor family rooms that are replacing more utilitarian decks and porches in the Washington area. “The trend is to turn a piece of the garden into a place to enjoy nature with all the comforts of home,” Rill said.

The architect designed the Suttles’ backyard retreat so it can be used in all seasons. A stone-faced fireplace heats the space in winter and a ceiling fan supplies cooling breezes during warmer months. A lantern at the top of the pyramidal slate roof filters daylight into the space and hanging light fixtures brighten the interior at night.

Low walls around the perimeter and comfortable furniture provide places to sit and dine. The pavilion even has its own porch, a mahogany pergola that extends over the terrace next to a swimming pool.

“Life has gotten to be incredibly complicated and intense during the work week, so these types of spaces are critical to your composure and time spent relaxing,” said Georgetown architect Merle Thorpe. “Outdoor spaces can be transformative in their ability to effect change of outlook and mood.”

Thorpe says the success of a porch, deck or pavilion depends on its relationship to the house and yard. “The architecture of a porch can extend the house style or provide another definition altogether,” he said. “If your intent is to integrate the porch into the yard, you need to minimize the number of steps and visual barriers between the two. Decking can become an extension of the floors in the house, and porch ceilings can also relate to ceilings inside.”

The architect’s advice is evident in the spacious back porch he designed for Cleveland Park homeowners Martha and Robert Vicas as part of a kitchen and master bedroom addition. “It’s become our outdoor living and dining room,” said Martha Vicas, an interior designer. “We use it during most of the year, and it brings a lot of light into the kitchen.”

Screens or curtains?

Like the Suttles’ pavilion, the porch has a large fireplace, a ceiling fan and cushioned outdoor seating. Paired columns along the perimeter support a green roof planted with sedum and serve as an armature for climbing vines.

Instead of covering the porch with fixed screens, the couple installed curtains made of mosquito netting that can be pulled across the entire length to keep out insects. Marine snaps along the bottom of the fabric can be attached to the floor so the drapes stay in place.

“I don’t love the look of screened porches; they look dark,” Vicas said. “I like the limitless feeling of a porch when the curtains are open.”

But in swampy Washington, many homeowners prefer porches with permanent screens to shield them from annoying summer pests. “Everybody wants an open outdoor space until they have one and discover the heat and the bugs,” said Bill Millholland of Case Design/Remodeling in Bethesda.

A few years ago, Millholland said, outdoor kitchens were a big trend, but homeowner interest in such patios with built-in grills, sinks and refrigerators has waned with the economic downturn. “Most people are interested in a screened porch and making it an extension of the house with nice details, furniture and speakers, even TVs.”

“Outdoor kitchens might work in California but they don’t work in this area,” said homeowner Cindy George, an accountant with the federal government. “No one wants to sit outside in a kitchen with 90 degree heat and 90 percent humidity.”

George and her husband, Tom Jackson, a lawyer, hired Case to add a screened porch to their 1920s house in Chevy Chase Village. “We had a deck but we never used it,” she said. “It was too buggy, and we had to spend time cleaning off debris.”

The deck was preserved, however, and reinforced with new supports to serve as the platform for the new porch. New decking made of ipe, a tropical hardwood twice as strong as oak, provides durable flooring. Skylights in the porch ceiling bring in daylight to keep the enclosure from appearing dark.

“The porch has expanded the rooms of our house,” Jackson said. “When we have parties, it provides extra space to entertain and flow through.”

The homeowners estimate that they spent about $60,000 on the 15-by-25-foot structure. That’s about average, according to Millholland, who says constructing a new porch in the Washington area “can cost as much as an addition,” from $30,000 to more than $100,000. “It really depends on the size, the shape, the quality of materials, how high off the ground it is and how many renovations have to be done to open the exterior wall and connect the porch to the house.”

But don’t expect to recoup all of the expense. According to District realty agent Kimberly Cestari of WC&AN Miller, decks increase the value of a home by about $5,000 to $7,000 and screened porches by about $7,000 to $10,000.

Before deciding to build, experts recommend that homeowners think about how the porch will function to determine its size and shape. “Do a furniture plan showing how sofas, chairs and dining table will fit into the space,” said architect Bruce Wentworth of Wentworth Inc. in Chevy Chase. “Porches are often a big investment, so you want to get as much use out of the space as possible.”

Choosing materials

Experts say materials should be considered for their durability and ease of maintenance. “Pressure-treated lumber is a popular and cost-effective material, and has evolved in recent years,” said builder Ethan Landis of Landis Construction in the District. “The toxic chemicals once used to treat the wood have been banned by the EPA, and new regulations are in place.”

Until 2004, chromated copper arsenate was commonly applied to pressure-treated lumber, but has since been replaced with less toxic alternatives.

Still, affordable pressure-treated yellow pine has its drawbacks, Landis said. “It tends to look weathered after five to 10 years and needs more maintenance than other materials.”

Tropical hardwoods such as ipe and mahogany are more durable, he said, but they may not be the most environmentally friendly choices. “A lot of mahogany, ipe and teak are endangered wood species that we use sparingly. There are some exotic woods that are grown in a sustainable fashion, including some ipe and lyptus [from the eucalyptus tree].”

In choosing ipe, DIYers beware: Because the reddish wood is so dense, it can be difficult to saw and nail or screw. Landis said cedar requires the use of specially coated or stainless-steel fasteners, since ordinary screws or nails “can cause a chemical reaction that can cause dark streaks in the wood.”

Growing in popularity as alternatives to wood are composite decking, made of wood fibers and recycled plastic, and lumber made from plastics such as polyvinyl chloride (PVC) and polyethylene.

Plastic and composite materials offer the advantages of weather- and insect-resistance and low maintenance, he said. They don’t need to be sanded, refinished or stained like wood. Some composites, however, will fade and decay over time.

But synthetic materials are more expensive than conventional wood construction. According to Wentworth cost estimator Michael Nastasi, typical pressure-treated lumber costs about $15 per board, while a composite board of the same size can cost about $40 to $70. Ipe decking runs about twice the cost of its composite equivalent.

For the Suttles’ garden pavilion, Rill chose mostly natural materials, including fir for the interior framing. Flagstone flooring inside the structure extends the paving of the surrounding garden terrace. The clustered columns at the corners of the structure look like they are made of wood, but are really fiberglass.

“There are many good solutions being offered now that are durable and minimize maintenance,” Rill says. “With careful design considerations, you can create an outdoor room that seamlessly transitions between the house and yard.”

Deborah K. Dietsch is a freelance writer.