FACADE:

The brick façade on existing Grant School underwent a complete masonry restoration. Damaged bricks were replaced and existing bricks were repointed. The new addition sports a glass curtain wall façade facing G Street.  Brick that was used on the new portion of the school, which matches the original brick, sits in front of an8” concrete masonry wall with a 2” rigid insulation and a 1.75” airspace.  Aluminum composite metal wall panels with a thermoplastic core sitting in front of an 8”concrete masonry wall were also used on the new addition.  

ROOFING:

On the existing building, slate shingles on .75” plywood witha 3” headlap will remain for historical reasons.  On the new portions of the building, a white, thermoplastic membrane roofing resting on 2” rigid insulation was used.  The outdoor roof terrace was fitted with hydraulically pressed concrete roof pavers. 

SUSTAINABILITY FEATURES:

The use of outdoor roof terraces creates additional outdoor spaces for a school which has limited outdoor lounging area.  Light wells are situated on these outdoor spaces to allow natural sunlight into the main floor below.  Large glass windows and curtain walls are used on the new addition to allow for natural sunlight as well.  Electric window shades and light blocking fiberglass shades aid in controlling light permitted into the building.  An atrium space created between the old building and new building provides natural ventilation to the main three floors. 

STRUCTURE:

The existing school building relies on load bearings masonry walls and wood joists to support its structure. Both the existing building, and new addition utilizes a shallow foundation which includes strip footings and grade beams. The foundation of the existing building, at the point where it meets the new building will be underpinned.
The new addition of the building relies on structural steel framing with a composite metal deck. The building uses a lightweight concrete topping on most of the deck surfaces. Typical beams in the building range from W10 to W24 sections and typical columns range from W10 to W 12 sections. Lateral loads in the building are resisted by a combination of braced and moment resisting structural steel columns.

MECHANICAL:

The mechanical system that was previously served the original building was completely removed and replaced. Air is supplied to the existing building and is ventilated by a four pipe central ventilation unit (100%O.A.). A gas fired ventilation unit (100%O.A.) supplies air to new building.  A central chilled water system supply chilled water to all four air handling units and a central hot water heating system consisting of two gas fired boilers will supply heating water to all air handling units. Exhaust fans were installed in the basement that were specifically dedicated for science room fume hoods and kiln rooms. The construction team ran into many problems when accomplishing this overhaul on the mechanical system due to the fact that the wood joists of the building ran in both the north -south and east-west directions limiting the area allowed to run ductwork and piping.

ELECTRICAL:

A 3 phase, 4 wire, 208/120V system supports both addition and the existing school buildings. The total connected load of the system is 522.3 kVA and the total demand load of the system is 463.8 kVA.

FIRE PROTECTION:

Spray applied fireproofing is used on the underside of the metal decking located in the new addition of the school. The building is designed for a 2 hour fire rating at the first floor, and a 1 hour fire rating at the second, third and fourth floor. The floors located in the existing school building are rated for 1 hour. This fire rating is achieved through the use of multiple layers of 5/8 "GWB. This wall board is connected directly to the underside of the wood joists.

A horizontal fire shutter is located at the third floor of the atrium space of the building. In case of a fire, this shutter would close automatically to prevent the spread of fire to the multiple floors above or below.