Capital Hill, DC Roof Deck
We designed, engineered, and constructed a roof deck on this 115 year old Capitol Hill mansion, to make it a safe and comfortable family relaxing space. The home was in a historic district so any modifications either couldn’t be visible from the street or needed to appear original to the home. NARI CotY Grand Award Winner 2011
|Before and After – Roof Deck|
We designed, engineered, and constructed a roof deck on this 115 year old Capitol Hill Mansion, to make it a safe and comfortable family relaxing space. The home was in a Historic district so any modifications either couldn’t be visible from the street or needed to appear original to the home.
Unusual Constraints / Challenges
• Then there were the structural challenges which were significant. The roof had a sloping section which the deck was to cover. Soon into the design process, it became clear that the structure of the home would require a significant quantity of steel to span the party walls.
• Creating an access to the new roof deck was also an issue because there wasn’t an obvious place within the home to build it.
• When you open up the roof of a two million dollar home, you just know that’s when it will rain, and it did. Buckets.
• The desired roof deck finish was concrete pavers. Coordinating the delivery of thousands of pounds of pavers and steel and brick, along with a hot tub, onto the 45 foot high roof posed its own challenges.
To create a relatively flat substrate we essentially designed and constructed a new low slope roof over the existing one with a system of steel beams and a metal roof deck. This required building up the brick party/parapet wall front to back. To meet historic preservation requirements while creating a security railing, along the exterior walls we integrated new custom made matching wrought iron Cresting. This was chosen to match what we determined from historic photos of the home, had been original to the home.
Instead of trying to create access through the roof from inside, we constructed an extension of the existing spiral staircase. This provided safe and elegant passage to the roof without disturbing the recently remodeled third floor.
When we opened up the roof to tie in the new structural members there was a tremendous thunder storm. The homeowners happened to be on vacation so one of our carpenters spent several entire nights managing a small stream of water infiltrating at a few spots.
We were also able to improve the insulation value and energy efficiency of the home by insulating the new roof to a very high standard. The membrane roof was installed over 6″ of new rigid foam board. We also installed spray foam at the parapet walls, the existing mansard and the rear mansard roof.
We utilized two cranes and an external scaffold/stair tower to convey new material onto the roof and demolished materials off of the roof, and to minimize our interruption of the occupied interior of the home. Careful planning and a good deal of manpower made this all go smoothly.
In the end, the homeowners have an incredibly well designed and built roof deck capable of safely and comfortably hosting a party or just the family for a weekend of relaxing in their hot tub. They are thrilled with their new roof deck!
|Before and After – Floor Plan|