The renovation of the outbuildings behind 70 Tradd St. marked the first commission for Thompson Young Design.

It's also the firm's first award.

Admittedly, architect Simons Young had an inside track on the project. He grew up there, and his family has owned the property for generations.

From Tradd Street, about all there is to see is a circa 1774 home and adjoining garden, but this lot is a great example of the genius of Charleston's early builders who constructed outbuildings -- like kitchens and carriage houses -- both close by and out of the way, all at once.

Here, the outbuildings include a carriage house and kitchen building, which had slave quarters above. Both long ago were converted into apartments.

Thompson Young's goal was to refurbish these buildings yet again, fixing structural and mold issues while increasing the natural light pouring inside and upgrading the heating and cooling system.

Architects John Thompson and Young also designed yet another new segment to the rear of the carriage house -- at least the fourth time that either the house or its outbuildings have been enlarged.

The addition is diminutive, slightly lower than the neighboring carriage house and done with different materials in a way that's both different from -- and complementary to

-- the existing brick (not unlike the approach for the next most recent addition linking the main house to the kitchen building).

"We were trying to make the conscious line between old and new," Thompson says.

The design also reopened the stable door and converted another arched entry into a large window.

Inside, the design removed a warren of partitions that pent up the natural light -- which mostly came from the western windows overlooking the garden.

They improved the heating and air system by digging down about 2 feet under the first floor to make room for new duct work, a job that brought the bonus discovery of an unexploded Civil War shell that since has been defused and decorates an empty fireplace.

On the second floor, the architects saved the slate roof and left timbers exposed mostly below by inserting insulated panels between them. The baseboards and stair handrail were milled from original timbers below.

While the rear addition held much of the less glamorous utility stuff, like a washer and dryer, the architects needed to tuck an air-handling unit into the carriage house. Their solution is an unfinished white oak wall that masks the unit while providing access to it.

"This wall was a huge design challenge. We wanted to do something neat," Young says. The boards are separated by small metal washers to give them a different look from the hardwood floor.

Tupper Builders Inc. did the work, while Rosen and Associates Inc. oversaw the structural repairs, which mostly involved closing in a rear window and rebuilding that corner.

The Preservation Society gave 70 1/2 Tradd St. a Carolopolis award, noting the work "has allowed a historic service building to continue to be an integral part of the property."

Standing in the property's linear garden looking back toward the house, one can see more than two centuries of Charleston building history, from the main house to its rear additions and support structures to Thompson and Young's brand new addition at the back. "It's just enriched because you see the progression," Thompson says. "It all tells the tale."

In other architectural news, College of Charleston architecture professor Ralph Muldrow will lecture about the relationship between Charleston's Hibernian Hall and Girard Orphan's College in Pennsylvania. The free talk will be at 7 p.m. Wednesday in Room 309 of the Simons Center, 54 St. Philip St. For more information, call 953-3888.

Robert Behre may be reached at 937-5771 or by fax at 937-5579. His e-mail address is rbehre@postandcourier.com, and his mailing address is 134 Columbus St., Charleston, SC 29403.