KEC Week 19

This month MEP coordination continues and we have been using Building Information Modeling (BIM) for some of the more complicated spaces.

[perspective looking at building from the North]

[interior view of the attic mechanical space over the kitchen from the service hatch]

Onsite the underslab electrical and plumbing in the basement was completed.  A vapor barrier is installed to prevent moisture from working its way up from the ground through the slab and into the building.  Without the moisture barrier below the slab, moisture can come up through the slab and start deteriorating building materials such as wood framing and sheetrock and can also lead to mold growth.  The moisture barrier has been added to ensure good indoor air quality in the building.

[basement slab pour]

After the concrete slab is poured it must be properly cured.  There are several methods for properly curing a slab.  Curing compounds can be added to mix designs to help accelerate project schedules, however most agree that a "wet cured" slab is a better quality job.  To wet cure a curing paper is spread over the entire slab and it is kept wet for typically 7 days depending on the structural engineer's requirements for the project.  While this is happening, not much other work can happen on the slabs which is why some projects try to use a curing agent to allow work to continue on the slabs right away.  Again most would agree a wet cured slab is a better job and this is what we have done for this project.

[wet curing the basement slab]

At the North and West wings, activity has focused on underslab plumbing, underslab ductwork, and underslab electrical.  You have to install the deepest work first and then work your way up.  All work needs to be carefully coordinated so that the piping does not conflict with other piping and to also make sure it comes up from below the slab in the walls and not in the middle of a corridor or room where it doesn't belong.

 [underslab supply air duct]

 [underslab earth duct]

 [these underslab supply ducts will supply conditioned air to the corridor spaces through floor grills]

[here is a row of the floor gills in the corridor before being backfilled]

 [here is the row of floor grills after being backfilled]

 [forming the greenhouse stem walls]

 Slab prep is underway in anticipation of pouring the slab on grade for the West Classroom Wing and starting the timber frame installation next week.

  [underground electrical piping in lab areas]

 

[vapor barrier being installed under slab in lab areas]

The mason started the CMU block stairwell walls and elevator shaft and the framer has started in the East Residential wing.

[temp stair tower for access to basement]

[staging at the stair tower and elevator shaft]

[stair tower and first floor framing sill plate]

The timber pedestrian bridge will start next week.  Steep slope erosion control as well as disturbance limits and silt fence are installed to minimize impacts of construction on adjacent wetlands areas.

Geothermal well drilling is complete and they will focus next on the horizontal piping between the wells and the vault just outside the basement mechanical room.

[geothermal well field]

KEC Timber Frame and SIPS Shop Visit

We took a ride up to Bennington VT this past week to review the shop and witness our frame being fabricated which is a very interesting process.  Bennington is about 3 hours North of Choate by car and about 150 miles.  The company that is fabricating the frame is Vermont Timber Frames and their sister company Timberline is fabricating the Structural Insulated Panels (SIPs).

[timber frame and sips shop drawing]

There are a few different species of lumber being used for the timber frame on this project including about 16,000 board feet of Douglas Fir, 3,000 board feet of Alaskan Yellow Cedar, and 3,000 board feet of Eastern White Pine.  Most of the lumber is harvested from the Pacific Northwest and a majority is also FSC certified.
Vermont Timber Frame's shop is about 30,000sf and is run by about 8-10 shop workers.  Once the lumber is received at the shop it is run through a planer.

After going through the planer it is then put into the Hundegger K2.  This is a computer operated machine that cuts the timber joinery in accordance with the approved shop drawings.

After the timber is cut in the Hundegger K2 there remains some handwork to clean up the cuts and corners.

After the handwork, the timber is run through the planer one last time to make sure all cuts are clean and then the timber is oiled and stockpiled to be prepared to be shipped to the site.

When asked about FSC lumber, the manufacturer said that while they are very familiar with FSC lumber, they do not see the request in the project specifications all that often.  Most of their work is either residential or commercial.  For new residential construction, most of the project emphasis is for HERS ratings to achieve Energy Star rating.  This is essentially building a very air-tight home to reduce energy losses through the building exterior walls and roof, among other goals.  For their commercial projects, the clients have been less focused on LEED certification.  Institutional and Academic construction has been more focused on LEED certification and therefore that is where you see more FSC lumber specified.

Next we walked through the Structural Insulated Panels (SIPs) process.  A SIPs panel is a sandwich of 2 layers of Oriented Strand Board (OSB) on the outside and Expanded Polystyrene (EPS) foam in the middle.  It is used as the insulated roof deck and/or insulated wall panel.  SIPs are often selected for sustainable projects because of their excellent insulation rating.  A SIP panel that is 6" has an insulation or R-value of about R-25 while a 6" wood stud with fiberglass batt insulation would have an R-value of R-16 (http://siperiorhomes.com/advantages/)

On our project we have SIPs on the roof spanning over the timber frame.  The SIP is the insulated roof deck and then it is finished off with a layer of felt paper and an aluminum metal roof panel on top as the finished surface.  The SIPs are a combination of 10" thick and 12" thick depending on the location and achieve roughly an R-44 insulation rating.

First he equipment uses the suction cups to lift a large sheet of OSB and transfer it to the conveyor.

Next the OSB is run through a glue applicator where glue is brushed onto the OSB.  A sheet of EPS foam is then set onto the glue.  The panel is run back through the glue applicator and the top layer of OSB is set on top.

It runs down the conveyor where it is squared off to make sure the OSB sheets and the ESB sheet are all aligned and square and then it goes into the press.

In the press the glue bonds to all the surfaces.

When it comes out of the press the panel is complete.

After the panel is complete, any custom raceways or routing is done to allow for edge blocking or pre-wiring.

Once comple the panels are wrapped and prepared for shipment to the jobsite.

KEC Regional Materials

One of the strategies for obtaining LEED points is to use locally harvested and manufactured materials.  One may ask, what is considered "local"?  LEED defines regional materials as being BOTH  harvested AND manufactured within a 500 mile radius of the project site.  This radius is "as the crow flies" not actual travel distance.  So what does this radius look like for Choate?  Here is a helpful tool

Here is a list of many of the regional materials being used on this project:

• Recycled asphalt paving
• Landscape plantings
• Concrete and Rebar for foundations
• Stone veneer siding
• CMU block
• Precast lintels
• Structural and miscellaneous steel
• Lumber and plywood for framing
• Millwork
• Roofing
• Dampproofing and waterproofing
• Drywall
• Flooring

KEC Week 15

[foundation wall at greenhouse transition]

Over the past few weeks good progress has been made on the building foundations.  Building foundations are now complete with the exception of one of the basement walls which was left open to allow trades access to the basement slab area where under slab piping is being installed.  Greenhouse foundations are in progress.

[basement foundation walls with area left open for access to basement; electrical conduit and underslab plumbing in progress]

Underslab plumbing work is in progress.  Here you can see waste lines which drain the floor drains in the basement mechanical room.

[underslab plumbing]

On the outside of the foundation frost walls, dampproofing and rigid insulation is being applied.  The dampproofing and rigid insulation help create an energy efficient high quality indoor environment that keeps conditioned air in, unconditioned air out, and unwanted moisture out, preventing issues with mold and air quality.

[damproofing and insulation on frost walls]

The details at the basement foundation walls are slightly more involved because the area inside of the basement walls is an occupied space as opposed to the frost walls which are completely below grade on both sides.  So because the basement is an occupied space you must do more to ensure no water finds its way through the basement walls or up through the concrete slab floor.  On the exterior a waterproofing membrane  is first applied to the foundation wall.  This prevents groundwater from permeating through the foundation. Next a drainage board is installed. This gives groundwater that is up against the foundation a way to drain down the face of the foundation.  Finally the rigid insulation is installed over the drainage board to provide a thermal barrier between the conditioned indoor space and the unconditioned outdoor space.  Prior to backfill, a foundation drain will be installed so that water running down the face of the foundation wall via the drainage board is collected by the foundation drain and brought away from the foundation and tied into the stormwater management system.  The waterproofing and dampproofing products help contribute to LEED points on the project because they contain both recycled and regional (within a 500 mile radius) materials.  Here is a sample letter from Grace and how its products contribute to LEED points.

[basement walls with waterproofing membrane, drain board, and insulation]

Outside of the building there is a lot of activity on site as well.  Materials for the Earth Duct have arrived onsite and we are getting ready to start this installation.  The geothermal well driller has mobilized and has started drilling.  There will be a total of (25) wells each 400' deep.  Each well will take between 1 and 2 days total, so the entire drilling process will take about 6 weeks.  The location for the new timber pedestrian bridge to connect the visitor parking to the KEC site over the stream is being laid out with selective clearing to allow for the installation of the bridge.  The bridge installation will start in August.  New utility services have been connected at East Main Street and run to the building for stormwater, electricity, water, fire, and sewer.

[earth duct stockpiled on site]

[underslab duct stockpiled onsite]

[geothermal well drilling has started]

[location of new pedestrian timber bridge]

[steep slope work for new utility connections at East Main Street]

[water and fire service to building from East Main]

[electrical primary service from East Main]

[electrical distribution between East and West wings, under courtyard]

[onsite material stockpiles for topsoil and subgrade materials being stoed onsite for reuse.  Topsoil pile was temporarily seeded to prevent erosion and airborn dust]