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]

KEC Week 12

The past few weeks the focus has been on foundations.  The East wing of the building has a full basement which will be used for mechanical and electrical rooms, laundry, and storage space.  The rest of the building foundation is a slab on grade with frost wall foundations.

 [ concrete crew laying out foundations, they "step" down at this corner to allow the Earth Duct to come under the slab]

To build the foundation you start with the footing.  Wooden forms are used to create the footings.  Sometimes reinforcing steel or rebar is required in the footings.  After the forms and rebar are installed, the concrete is placed in the footing.  When the concrete hardens, usually about a day later the forms are stripped and then the foundation walls are formed on top of the footing.  

[foundation wall in progress, some wall is complete while the foreground shows rebar in progress]

[ basement foundation wall in progress, that opening is for a louver into the mechanical room for fresh air ]

[ concrete crew working on basement foundation wall forms; in the foreground is the elevator pit]

[this is the NE corner of the building, near the new kitchen, the carpenter is installing a brick shelf that will support the stone veneer]

You usually start by building the outside formwork, then install the wall rebar, and then close up the wall by installing the inside formwork.  Then concrete is placed in the walls.  Often this is placed using a concrete pump truck.  Again, when the concrete hardens the forms are stripped and now the foundation is complete.   Since the basement is a finished space, it is important to properly waterproof the outside of the foundation walls, provide good drainage along the wall and away from the building, and provide insulation.  We will start this work in a couple of  weeks and I will discuss these methods in more detail at that time.

Where there is no basement we have frost walls.  The steps are generally the same, start with the footing and then build the wall.  The main difference is that this is only a frost wall which means you only go deep enough to prevent the effects of frost heaves in the winter when the ground freezes.  In New England this is typically between 3-1/2 and 4 feet deep.  Since there is no finished space behind the frost wall and the slab is on grade, waterproofing is not usually required on these walls, but it is still a good idea to use damproofing and insulation.

   

[here is the frost wall with just the outside forms up]

[here the frost wall has been closed with the inside forms up]

While the foundation work has been advancing, we have also started work on the site utilities.  We have connected the site storm drains, domestic water service, and sewer service to the town utilities in the road.

While all this activity is taking place on site there is also a lot of work in the office, pre-planning site activities.  Shop drawings are being prepared by the various subcontractors for the elevator, timber frame, mechanical equipment, and electrical equipment as well as coordination drawings locating all of the piping and ductwork below the slab, above the ceilings, and in the walls.  These shop drawings and coordination plans are reviewed by the design team and the Construction Manager to coordinate with the design and each other's work to ensure when all the materials arrive onsite they can be properly assembled without any issues.  This is a very critical part of the project that avoids issues on site which can lead to delays and costly changes.

@Home: Low VOC Paint

Everyone has heard the saying, "You can talk the talk, but can you walk the walk?"
It's real easy to read about building "green" and get excited about it at work and talk it up with clients, especially over the past few years where it has been such a buzz in the industry.  But when it comes to making changes in your own home, you have to ask yourself how willing are you to go ahead and try new things?  And if you aren't willing to try it yourself, then should you really be advising others to do so?
At home I've been picking off the low hanging fruit like adjusting thermostat set-points,  recycling at the local recycle center, changing incandescent lamps to compact fluorescents, using cold water and light load on the washer machine, and reducing length of showers to name a few.
This past weekend my wife and I decided to change the paint color in our daughters' bedroom.  We picked out colors from a Pottery Barn catalog and then went on-line to confirm products.  I was happily surprised to see that Pottery Barn recommends a Benjamin Moore product called Natura Zero-VOC Interior Paint.

I priced out some options and found Natura to be around $52 / gallon.  Another Zero-VOC option that Benjamin Moore offers is called Eco Spec and this was closer to $30 / gallon.  When I asked the paint dealer the difference he explained that the Natura provides better coverage as it is a higher quality paint.  This price range between a high quality product and a mid to low range product was typical for Zero-VOC, low-VOC, and standard paints alike.  And it is commonly stated that a more expensive paint is a higher quality paint which provides better coverage and can equal less coatings and therefore less labor.
So after weighing out a few options, I decided to go with the Natura and see if I noticed any real difference.  I picked up a gallon of primer and a gallon of eggshell and got to work.  It went on very smooth and even.  It dried fairly quick so I had to make sure to apply it evenly and finish an entire surface at once to avoid flashing or patches.  I did notice one significant difference - the lack of odor.  I was really amazed by this.  Quite often you may be in a room painting then you leave the room to get lunch or take a break and you come back in and you are hit with the odor that you didn't notice before because you were in the room.  Well there was almost no odor and this was really amazing.
I remember working on a project at the MFA in Boston and the museum curators required a period in our construction schedule for "off-gassing" which occurred after construction was complete and prior to the return of the artifacts.  This was my first museum project and I was unfamiliar with the term so the curator explained to me that the materials in the newly renovated space give off gases that are harmful to the artifacts and they needed a period of time for the highest concentrations to dissipate before they could safely bring the artifacts in.  I remember wondering if the fumes were so harmful to these artifacts, why wouldn't they also be harmful to people?  This was a few years before LEED became prevalent in construction projects.  But when LEED did come out I was happy to see an emphasis on flushing out the building prior to occupancy to protect the new occupants from odors and fumes from the new materials.
All in all, I was very happy with Natura and I felt good about the decision to use a Zero-VOC paint in my home, especially in my daughters' bedroom, and I would continue using this paint and recommend it to others.

KEC Site Plan and Elevations

KEC Exterior Wall Mock Up

At the start of a project it is very important to construct an exterior wall mock up.  The mock up is used for several purposes including material selections, constructability, and performance.  This project team used the mock up for final exterior material selections and to review constructability details.

We first started by placing the concrete slab.  This allowed us a trial run on the concrete mix design and resulted in some modifications to the mix design to allow the concrete to be more workable during the placement.  

[mock up slab pour]

Next we framed the walls and roof with 2x wood framing and plywood sheathing.  The building will be framed with FSC certified lumber.  Then (2) layers of 15# felt paper were installed as the buildings vapor barrier.  This is important to keep moisture out of the building.

[mock up wall framing and sheathing]

Next the stone veneer was installed.  The stone is a locally sourced fieldstone found in close proximity to the project site. 

[mock up stone veneer and cavity wall]

We sampled different mortar colors and joint types on the mock up so that the preferred color and joint method could be selected.  On the bottom wall section we used a recessed joint and the top section is a flush joint.  Because the stone has an irregular surface, the flush joint tends to look very wide.  The team preferred the recessed joint on the bottom half of the wall.  While installing the stone, the precast concrete sill was not yet available so we had to put in a piece of pink styrofoam to allow us to complete the stonework.  Then when the precast concrete sill was fabricated, we were able to slide it right in without holding up the schedule.

[mock-up stone veneer]

A sample window was installed.  The window is a Marvin aluminum clad wood window and the wood is FSC certified.  Next a base course of Trex was installed at the watertable at the very bottom of the wall.  Trex is very durable and corrosive resistant, does not need to be painted, and is made from 100% recycled material so it is a good choice for this application.  Then the cedar trim was installed which will also be FSC certified.  The roof is a painted aluminum standing seam metal roof with matching snow rails.  The siding on this project is a cement board product, which is an alternative to wood siding.  This is a good sustainable option because it is extremely durable, it outlasts wood, it holds paint very well, and it is also very fire resistant.  We sampled two different colors and manufacturers and the team preferred the top half which is Hardie Plank Countrylane Red.  The final step was to stain the cedar trim using a low VOC stain from Benjamin Moore.

[completed mock-up]

In addition to material selections, the team learned a great deal from the mock up.  We were able to work out some dimensional details on the stone veneer.  The concrete mix design was modified to allow a more workable mix.  Most important were the details on the cement board siding and wood trim.  This is not a standard everyday design because of the large exposure ship lap detailing.  The carpenter foreman had to set up custom jigs and experiment with the blocking and shimming and corner details until he was able to find a good compromise that met the design intent and would be a durable long lasting detail.  Again this is a very important exercise because it allows the team to work out many of the details on a small scale sample of the building that may not be evident on paper.  It provides a hands on opportunity for the trades performing the work to get familiar with the installation and raise any concerns to the team before working on the actual building.  This will ensure a better quality product and will avoid the potential for added costs and schedule impact down the road.