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.