Friday, July 31, 2009

Final section of parking deck poured

View of the parking deck from the entrance

The concrete mixture used in the parking garage is a made up of cement, sand, aggregate (small stones) and water. The concrete comes from the pump truck at the street, and is carried through a telescopic boom over to where the pour is happening. The final section of the boom is a rubber hose, seen below. A laborer controls the hose and pours the concrete into the rebar of the deck. The end of hose cannot be more then 4 feet above the placement, because the cement will separate from the aggregate.

With the concrete poured in place, a rake crew working alongside a cement finisher using a hand screed, which is an aluminum 2x4, move the cement to a rough grade. Next, a cement finisher using a power screed (seen below) and laborers with shovels and rakes bring the cement to a finish grade. The power screed had a small engine that vibrates the unit, which helps the stone aggregate settle down into the pour as the cement rises up, smoothing the surface.

With the concrete graded, it begins to set pretty quickly. As seen below, workers can already walk on top of the surface. A cement finisher uses a power float, also called a whirly bird, to pull the moisture up to the surface to prepare the area for the broom finish. Before this machine came around, this portion of the prep required multiple workers using hand trowels. The process is much more efficient thanks to the power float, it can manage a much larger area while maintaining flatness.

Finally, a cement finisher uses a bull float for one last pass to bring saturated concrete to the surface, making the area smooth. Pushing out with the bull float down, the moisture saturated concrete is brought to the surface. At approximately 20 feet out, he twists the pole, which lowers a broom attached to the end of the float. Pulling back towards his body, the broom runs along the surface of the concrete. The broom finish gives a level of coarseness, allowing for traction for both vehicles and pedestrians.

The surface is then sprayed with water to slow down the curing process. The entire area is then covered with burlap bags, which are also sprayed with water. The purpose of this is to keep the concrete from curing too quickly.

Friday, July 24, 2009


HVAC work continues throughout the building and has begun on the 3rd floor. HVAC, which stands for "heating, ventilating, and air conditioning," is sometimes referred to as climate control and is particularly important in the design of medium to large industrial and office buildings, where humidity and temperature must all be closely regulated while maintaining safe and healthy conditions within (

Ductwork deals with conditioned air, whether heated or cooled. The air comes from a rooftop unit that takes a percentage of outside air and combines it with air that is circulated throughout a building. Dampers throughout the ductwork open and close depending on how much conditioned air is required according to the temperature set on the thermostat.

The ductwork is being installed throughout the Carpenters Centers by sheet metal workers working for United HVAC. On each floor, once the rough sheet metal work is complete, the other mechanical trades can run their pipe work and metal frame work can begin.

There are fans on the roof that turn the air and push it down through the ductwork. Air enters the building through the diffuser ductwork, which connects to branch ducts that run horizontally across the ceiling of each floor of the building. The sweeping elbow units (like the one below) move the air between floors and allow it to turn direction to run horizontally throughout the building.

The air is moved along to the exterior walls where it is pushed down the wall and across the floor to the interior return registers. These return registers have fans that draw the air back up to the air handler on the roof. This conditioned air is then reconditioned and sent back down into the building.

The double wall insulated unit seen here weighs approximately 600 pounds. This unit carries the air from one floor through to another. Because the unit is passing through the concrete floor, the exterior cannot be wrapped continuously in insulation, so the interior of the unit is insulated, eliminating the need for exterior insulation.

Thursday, July 23, 2009

Exterior dens glass installed

This week, carpenters working for H Carr & Sons installed the dens glass on the exterior of the building along the Expressway. After the dens glass is in place, carpenters with Sunrise Erectors will install the ice and water shield. This shield is a sheet of rubberized adhesive that provides protection from ice and water. On top of the ice/water shield an aluminum grid system will be put in place in preparation for the installation of the Alucobond Panels.

Wednesday, July 22, 2009

Then and now

February 2009

July 2009

Friday, July 17, 2009

Second Section of Parking Deck

Crews began work on the second part of the parking garage this week.

Much like in the first section of the garage, the area was first excavated and footings were poured for the concrete columns. Reinforcing dowels project out of the footings. They are the structural stand of the columns that will support the parking deck.

The second section of the parking deck will terminate at the vertical face of the retaining wall. From that end to the street, there will be a concrete apron out to the sidewalk. The parking garage will stretch along the south side of the building, by abutter H&H Builders, to the southwest side at Dorchester Ave.

Visitors will enter from Dorchester Ave and drive up a slight ramp onto the top level of the parking deck. The entryway ramp will be centered to the parking deck. The ramp itself will be 32 feet wide, to accommodate traffic in either direction coming in and out of the garage, by approximately 25 feet long.

The upper parking deck will have 46 parking spaces, there will be 43 spaces in the lower deck. There will be an additional 6 spaces separate from the parking garage at the North end of the building.

The majority of the parking deck, including the entire upper parking deck will be a concrete surface. One section, however, from the base of the ramp at the south side of the parking deck down to the lower level and the first section of the parking decking will be bituminous asphalt. In the lower level of parking deck along the abutter’s side, two vent windows were put in place to create cross ventilation. Asphalt will smoke and burn during a fire, so fire code requires proper ventilation in areas asphalt will be used. Due to the concrete retaining wall along the north section, the lower level in this area of the garage will be concrete, which will crack under heat but will no smoke/burn as asphalt does.

The following blue print highlights the area of the ramp and lower level of the garage that will be covered in asphalt instead of concrete. The pink highlights indicate the vent windows along the abutter’s side of the garage. The rendering below the prints shows that the Expressway side of the lower parking deck will be open, allowing air to move freely into the space.

With the columns in place, the peri system is currently being installed. The reinforcing rod will be installed by the ironworkers late next week. In approximately two weeks the second section of the parking deck will be poured.

Monday, July 13, 2009

Roof Work Contines

Last week, the interior frame work was completed on the roof and the dens glass was installed. Crews working for Oak Roofing and Sheet Metal installed the dens glass and covered it with a polyvinyl reinforced vapor barrier. This barrier prevents water that condensates between the layers from penetrating the walls.

On top of the vapor barrier, three inches of rigid Styrofoam insulation was installed, followed by a layer of asphalt-backed drywall. Finally, the wall was covered by a layer of thermoplastic polyolefin (TPO). The TPO along the walls overlays on the roofing TPO to prevent leaks.

On the q-deck on the roof, a similar installation occurred. A vapor barrier was installed and a 6-inch Styrofoam insulation was put on top (seen below in pink). The next layer is drywall with an asphalt coating, which is attached to the q-decking underneath using 9-inch screws.

Last week Oak Roofing and Sheet Metal Foreman Willy Hernandez worked with a crew of nine roofers.

With the drywall screwed in place, the TPO can be installed (seen here in white).

Friday, July 10, 2009

Parking Deck Retaining Wall Completed

Carpenters working for S&F Concrete poured the concrete for the retaining wall at the northwest section of the parking garage. The area in front of the wall continues to be cleared out, with the dirt being used as back fill on the other side of the retaining wall.

Early next week, crews will strip the peri-form work of the first section of the parking deck. The form system will be cleaned and used for the remaining section of the parking deck.

Meanwhile, the first section of the parking deck has been covered with an insulation blanket to prevent the sun from curing the concrete too rapidly.

Thursday, July 9, 2009

Concrete Poured for Pavilion

Before the concrete pour, polyvinyl chloride piping was installed in the slab of the pavilion. This piping is able to be bent and looped as seen here. Much like the stairs in the garage, heated anti-freeze will be pumped through these pipes during the winter months to heat the atrium entrance way.

The pavilion atrium is located halfway between the first and second floor. It is the the main entrance to the building. Upon entering, visitors will check in with the security guard and then take either the stairway up half a level to the second floor, or an elevator up to the second floor or down to the first floor. The floor in this area will be stone tile and the walls on three sides of the atrium will be aluminum framed glass walls.

As with the concrete poured for the first section of the parking garage, test cylinders were made from the concrete poured for the pavilion floor and second floor lobby area. These cylinders will be taken off site to the Universal Testing Services (UTS) lab where they will be put in a press (7 days from the pour and 28 days from the pour). This test ensures that the concrete is cured to the proper design strength. By the 28th day, the concrete should be able to withstand 5,000 pounds of pressure.

Tuesday, July 7, 2009

Monday, July 6, 2009

Concrete Pour at Parking Deck

Laborers and cement finishers working for S&F Concrete poured concrete today for the first section of the parking deck.

Concrete mixers, like the truck seen below, typically carry between 10-14 yards of concrete. Most trucks arriving on site today were carrying 11 yards.

This first section of the parking deck will require approximately 380 yards of concrete.

The parking garage will stretch along the south side of the building, by abutter H&H Builders, to the southwest side at Dorchester Ave. Visitors will enter from Dorchester Ave and drive up a slight ramp onto the top level of the parking deck. Cars will get to the lower level of the deck by using the ramp at the south side. The stairwell connecting the lower level to street level will be heated for de-icing purposes. Plastic tubes will be laid out within the concrete slab that will pump heated antifreeze from the boiler room in the basement of the building.

There will be 95 parking spaces at the Carpenters Center.

Thursday, July 2, 2009

Concrete Pour at Parking Deck Scheduled

As mentioned in previous posts, the parking garage at the Carpenters Center is a poured in place concrete deck. Given the design of the building and the topography of the land up to Dorchester Ave, the garage slab elevation needed to be at 20.5 feet above sea level. This elevation gave the proper slope for the ramp.

A structural steel structure was not an option. If steel were used in the garage design there wouldn’t be enough height clearance for vehicles. The poured in place system, on the other hand, uses a temporary peri-form system (seen below), which allows for the steel required to carry the slab to be placed within the slab itself. Aside from the design benefits, the peri-system is aluminum and ergonomic, requiring less time to install and is easier to put in place. 4-6 man crew can lay 2,000 square feet in a day.

The peri-system was built up to the sides of the concrete column. The reinforcing bar (rebar) is put in place on top of the system and connected to the hook bars in the columns.

Concrete is then poured (scheduled for early next week, weather permitting) in place and the peri system is left in place for a full seven days while the concrete cures.

At the time of the pour, test cylinders on site are poured as well. After the 7-day period, these cylinders are tested to ensure the structure will be able to hold the load required. When the test cylinders meet the necessary requirements, the peri system can be removed from underneath the poured slab.

At the other end of the entrance, carpenters are doing form work for the retaining wall.

The concrete for the first half of the parking deck is scheduled for early next week. Work on the parking deck will continue in July.

The dirt area seen here will eventually be dug out and the soil will be used as back fill for the retaining wall. With the area excavated and graded, crews can begin work on the rest of the garage.