Thursday, March 17, 2016

For Love of Doug . . . Doug-Fir

Timber-Frame Workshop raising in Etna, NH.
(All photos by author except where noted.)


Doug with Tom Page in his Alstead workshop. 
Last week we paid a visit to our timber framer, Tom Page and The Timber-Frame Workshop in Alstead, New Hampshire. We had seen Tom and his crew—Chris, Jim, and Dave—raising barn timbers in Etna, east of Hanover, a few weeks before, and we were assured that cutting our frame was next on his schedule. I wanted to hear the whirl of the saws, see sawdust fly, and smell the pungent resin of newly hewn timbers. I didn’t get to experience any of that but did I not leave disappointed, having significantly added to my elementary education in timber framing.
A dozen huge Doug-fir timbers were laid across saw horses in the workshop, only a fraction of the 249 pieces of wood that comprise the massive puzzle Tom is creating in Alstead, in preparation for trucking it to Tug Mountain later in the spring for assembly. He had already completed the 61 braces called for in architect Andrea Warchaizer’s plans.



The timber frame overview.


To build this house we need two major sets of plans—timber frame and architectural. Husband Doug worked with Andrea first on the architectural plans and then, with her thorough knowledge of timber framing, she translated the center, open portion of the house into a set of detailed timber-frame drawings, some 26 pages, with six cross-sectional views termed bents.  Andrea is done and Tom’s work now is to design each woodworking joint, figure out how to make what is engineered on paper properly work in wood. And, while he is creating each very stable and practical connection, he is also creating something artistic and beautiful.


Markings for cutting on a king post.

In timber frame construction, most of the joints are wood-to-wood joinery. Metal straps are used in a few places such as securing the verticals to the foundation. Also, the rafter foot joint is secured to the plate by structural timber RSS screws, which are used a few other places. The process is truly awesome, especially to me, who, unlike Doug, Andrea, and Tom, is somewhat three-dimensionally impaired. All Tom’s beams will be notched to fit one another and then further strengthened with splines that are secured with oak pegs. In some instances the splines will be made visible or “revealed,” giving further character to the expert craftsmanship.

Tom's notes on plans for one of the bents.


The 61 braces, ready to go.

Just as an example of the complexity of this process, the center post, one of several “king posts” that run from foundation to roof ridge, is 26 feet long and has nine places where other girts or braces meet it. Needless to say, everything has to be precisely measured. At this point in the process, Tom and colleagues are halfway through laying out the work. In all it will take about a month of measuring, marking, checking, and rechecking. Only then will the sawdust fly and we will return to get part two of an elementary education in timber-framing from a master.
Wood ready for layout.

Into the Wood NH trivia: Douglas-fir trees grow to be very large (250 feet tall with diameters up to six feet) and are valued for their strong and stiff wood, among the hardest and heaviest softwoods in North American. The tree is named after Scottish botanist David Douglas, who introduced the conifer to Europe. Its common name is hyphenated because it is not a true fir (Abies genus), but is in its own genus: Pseudotsuga. Its scientific name, Pseudotsuga menziesii, honors Archibald Menzies, a Scottish surgeon, botanist, and naturalist who first described the tree in the 1790s. To further refine the nomenclature, there are two varieties, one costal (Washington, Oregon, into northern California as far as the Santa Cruz Mountains) and one interior (parts of Idaho, Montana, and Wyoming).
Our wood comes from Port Orford, Oregon, the costal variety, it grows taller, straighter, slower, and with tighter grains than the interior variety. It is a mighty Doug! The second tallest tree ever recorded (the tallest is a Redwood) was a Douglas-fir, felled in Whatcom, Washington, in 1897; it measured 465 feet tall and 11 feet in diameter, yielding more than 96,000 board feetenough wood to build almost seven house frames like ours.
(Photo from nativeplantspnw.com)






























































Into the Wood NH trivia: Douglas-fir trees grow to be very large (250 feet tall with diameters up to six feet) and are valued for their strong and stiff wood, among the hardest and heaviest softwoods in North American. The tree is named after Scottish botanist David Douglas, who introduced the conifer to Europe. Its common name is hyphenated because it is not a true fir (Abies genus), but is in its own genus: Pseudotsuga. Its scientific name, Pseudotsuga menziesii, honors Archibald Menzies, a Scottish surgeon, botanist, and naturalist who first described the tree in the 1790s. To further refine the nomenclature, there are two varieties, one costal (Washington, Oregon, into northern California as far as the Santa Cruz Mountains) and one interior (parts of Idaho, Montana, and Wyoming).
Our wood comes from Port Orford, Oregon, the costal variety, it grows taller, straighter, slower, and with tighter grains than the interior wood. It is a mighty Doug! The second tallest tree ever recorded (the tallest is a Redwood) was a Douglas-fir, felled in Whatcom, Washington, in 1897; it measured 465 feet tall and 11 feet in diameter, yielding more than 96,000 board feet or enough wood to build almost seven house frames like ours.




Saturday, March 5, 2016

Too Much of a Green Thing: Passive Solar, Triple Glaze, and SIPs Gang Up


What a difference a year makes. Last year this time.
(All photos by author.)
In our approach to designing our mountain-top home we planned on taking advantage of a southern exposure that also, fortuitously affords a gorgeous view of a large and majestic Cardigan Mountain facing our Tug Mountain. To minimize energy consumption we opted for triple-glazed Fibertech fiberglass windows (see blog Sunday, February 14, 2016, Window Shopping in Canada). We also purchased and planned for multiple wood stoves as major sources of heat. Just this week we made another important design decision that will make our house even more energy efficient. The entire construction will be out of structural insulated panels or SIPs.
A section of a SIP
Doug at right conferring with Pete
in  front of foam at Foard Panel
 
The main section of the house is a barn-like timber frame with the open floor plan of high-ceiling living room and dining area, a kitchen with 9-foot ceilings and a loft over it. This rectangle was always going to be sheathed in SIPs, a popular choice for timber frames. SIPs are ideal for timber frames because they can cover a large span without additional structural elements. Two “wings” off the timber frame accommodate entrances, sun room, laundry room other living (and sleeping) areas, and bathrooms. We weren’t sure if they would be “stick-built,” traditional two by six construction, or made of SIPs, which are super-insulated. After careful evaluation of price proposals and other considerations (such as how to integrate two stick structures with a timber frame) we’ve opted for all-SIPs.
What are SIPs? They are fabricated building panels, a sandwich of expanded polystyrene (EPS) or Styrofoam (think cheap picnic cooler) insulating foam core between two sheets of oriented strand board (OSB). OSB is considered an environmentally responsible building material made from fast-growing young trees and residual parts of larger trees that have been sized for lumber. The SIPs are manufactured (in our case by Foard Panel in West Chesterfield, NH) to fit exactly the walls and ceiling of the house. After the timber frame is up, the SIPs are trucked in and put in place with a crane, then fastened together and to the sill plane, and sealed with triple expanding spray foam.


Foard Panel's headquarters
According to the Structural Insulated Panel Association web site (sips.org): “Building with SIPs generally costs about the same as building with wood frame construction when you factor in the labor savings resulting from shorter construction time and less jobsite waste. Other savings are realized because smaller heating and cooling systems are required with SIP construction.” Fans of SIPs say that they have less impact on the environment than traditional construction methods over the life cycle.
Our roof SIPs will be 10 ¼ inches thick with an insulating value of R38. The walls will be 6 ½ inches thick, with an insulating value of R24. With such major insulation we will have what is considered a “tight” house, one that has very little air transfer. In New Hampshire, with traditionally harsh winters, that means the warmed air stays in, the cold air stay out. Mission accomplished. We’ve surpassed our green goal.
However, we have a created a new problem. The house also needs to breathe, to let out musty, humid air in exchange for fresh, oxygenated, new air. In an old-fashioned, drafty house such as the 1912-built Victorian we are renting while under construction on the mountain, there is no issue of breathing. Air is exchanged regularly with the outside through inferior construction methods, abysmally inefficient windows, and poor (or no) insulation. The combination of SIP construction and triple-glazed windows raises the concern that we could create a negative pressure condition in the new house. If we had a wood stove burning, drawing oxygen from the living room, and the oven baking, pulling in air from the kitchen, we could turn on the range hood and create a dangerous smoke situation in the house. So we will have to add another system, another layer, an air exchange system to breathe for the house.

Breathe; it’s what I tell myself when I am anxious. Too bad a mantra doesn’t work on a house.