Update 6_2_11 When we last visited this job, we discussed valley sets, soffit assemblies, kerfing radiuses, and I believe girder trusses. Embarking and elaborating of some of those themes, the roof sheathing is now being applied covering all of the mentioned items. Let’s visit them again before they are totally obstructed from view (and our minds because the smooth transitions from one to the other the sheathing creates makes them vanish from both). No problem there right? We know what is going on beneath and the fact we don’t hear or see them again just means they are silently performing their individual tasks and functions. That’s a good thing.
The roof sheathing can be either 7/16″ OSB (Oriented Strand Board) (think Timber Strand in looks) or 5/8″ OSB or substituded with plywood, per builder’s preference. Ultimately, the sheathing is covered in 15lb or 30lb felt prior to shingles, hip and ridge, 3 tab, and starters being applied. We will save roofing for another lesson. The importance here on the selection of material between the plywood and OSB, for me at least, is the length of exposure prior to felting. Personal opinion but I believe OSB board “weathers” better than plywood. Clips to hold the 4′-0″ x 8′-0″ pieces together are used as well, kinda a double “U” bracket if you will.
I am showing a close up of the kerfing process to demonstrate the computerized fragmentation process. This “sliting” of the 2×6 lumber is how the radius is acheived. The other picture shows the Timber Strand header above as well as a diagonal brace held in tension, transfering load off of the opening below, which will ultimately be a window or in this case a door, that need to operate smoothly and without overt pressure being applied. Uhhh, glad I am through with that run-on sentence. The mouthful states one of the most beneficial reasons to use the wall panels; the use of engineered products designed to specifically address issues which conventional lumber (and framing) is ill suited to handle. Again personal conjecture here, but I mean LOOK AT IT! Which would you rather be hidden in your walls? Wish I had a camera with a better zoom, regardless, the point is made through the illustration.
Last but not least, is the ceiling plane made by the vertical rise of 2′-0″ at the edge the dining room (?) which is called a “tray” ceiling. Depending of what school of general architecture you subscribe to, it is also spelled “trey”. I always thought that was the fancy spelling (like the word old and olde) but who knows? Better yet who cares? No matter how you spell it, this creates a great look, and is used frequently. The interesting thing about this tray is the opposite side, where it is intercepted by a girder truss. You remember from the last post, the girder is a multi-ply member that is designed to carry uniformed (in this case) loads from the tray ceiling trusses, or “point” loads usually where another girder or beam intersects. Note the tray maintains in height by membering into the girder, which also has the same height tray in it via the metal hangers. The reason for this is due to the originating plane established. That sounds like another lesson and some illustrative pictures to explain to be offered at another time though, so lets leave it at that. On one of the original posts on this page, I mentioned the “broken” pitch overhangs. Now that the sheathing is applied, you can see what I was referencing. The overhangs when referenced from the peak or ridge of the truss go down on a sharp pitch, then break off on another shallower pitch. Another classy look, typical of the houses’s style.
Update 5_24_11 In visiting the site today, we begin to see the processes of continuing planes and adding detail to rough framing. In areas where roof planes run perpendicular to intersecting planes a valley is used. A component valley set consists of pre-manufactured valley members diminishing in lenght as they climb the intersecting roof. Shown here is a raftered valley set, which starts with a ridge board at the peak of one roof and continues to the apex of the intersecting roof. Rafters then are placed 16″ on center onto “sleeper” boards which form the same diminshing effect by continuing to be cut shorter on each side as they climb the intersecting roof plane. In the picture showing the valley configuration, you can see rafters placed perpendicular to “girder” trusses. This is called “ladder” framing and is used at stairway locations when as the stair rises, it goes through the ceiling plane. In this example, it is the stairs leading from the house into the bonus room above the garage. Girder trusses are designed with special loading conditions so they may be placed further apart than the standard spacing and have uniformed loads applied from the ladder framing. This is usually accomplished by making the girders “multi-ply”, which is just another way of saying there is more than a single truss. They require special nailing to develop the necessary reactions, sometimes special lumber or greater sized connector plates to accomplish this feat. Depending on the load they are required to carry, or the space they are apart, they can possibly be three plies but never greater than four. At four plies, it becomes increasingly more difficult to connect the plies, and even wood screws versus nails do not work. In some of the other pictures, the 2×6 subfascia is being nailed to the overhangs. Once this is returned to the house, it will form the soffit and will allow ventilation between the spacing of the trusses to the lower part of the attic space and create the eave assembly. The other photos demonstrate the arched interior wall panels, created by “kerfing” lumber into a radius shape. This gives the home the Tutor feel of Olde Worldliness..
5_18_11 Update: Progress is continuing at the jobsite as evidenced by these new photos. All walls are standing and the roof truss are on, for the most part. There is a tremendous amount of permanent bracing required on a roof system of this size. The tallest trusses are shipped as two pieces, the base truss is approximately 12′-0″ tall and a “cap” truss has to be installed to complete the triangular configuration. This “cap” truss is referred to as a “piggyback” truss. The piggyback trusses have a 1 1/2″ space to allow for purlins (2×4′s laying flat) at 24″ o/c between them and the base truss. This forms the connection between the base and piggyback trusses, which is completed with 6′-0″ “scab” lumber at the outside ends. As you can see from the photo on the left, the purlins were being installed when I arrived. Once completed, the piggy back will form the main ridge of the house. I met with the general contractor, framer, and homeowners, discussing various questions, reviewing details, and examining work. Next step is sheathing the walls and roof trusses to get things dried in. One of the best parts of using wall panels is the rough openings for the windows and doors are already in place. This will cut down on the time required to install them. The front of the house has alternating plate heights, 12′-0″ on each side, jumping to 14′-0″ at the entry. There is a flat area in the front above the walls that adds definition to the dormers. This is accomplished by the height of the truss “heel”.
5_6_11 Update: Finally got back to this site in the early afternoon. Some rainshowers kicking up after I took these photos and the erection crew had left. My real intent was to get here and show a truss delivery on the roll bed trailer but my timing, as usual, is slightly off. The 1st shipment of trusses is coming in today with the balance coming in Monday. The walls are looking even better standing. As I had figured, this is a very impressive house. Different structural engineers have different specifications. As component manufacturers, we need to realize what each one expects typically because we don’t always have all the construction documents at once in beginning the design process. Designing walls adds a new element of complexiety in anticipation of what expectations we are working towards. We use the roof design first in the process. Starting from the top of the structure shows where walls require load path studs installed and ultimately where the foundations need to be thickened to accept these loads. At window and door openings, headers are installed to transfer loading to both sides of the opening through stud clusters. This is, in my mind, where wall panels differentiate themselves from conventional framing techniques. In planning ahead of the construction process, wall panels utilize products like Timberstrand, LVL’s or composite beams according to the load transferred. Panels use the correct product to match the situation. I am not insinuating conventional framing methods are incorrect, just not as exacting to the individual circumstance. Interior non-load bearing wall headers, for example, may be conventionally framed with 2×10′s which is not necessary. It is great to have software to analize the situation and use innovative products to solve load equations.
I am really excited to track the progress of this house. It is an English Tudor European style home that occupies one of the nicest lot I have seen in recent memory. To the right is Shaftsbury Glen clubhouse. The front view is a breathtaking view of the golf course and the main road leading into the development. In typical Tudor style, this house will have steep pitches, prominent cross gables, tall narrow windows (which I have been calling tower windows for lack of a better word), and half timbering. This creates the illusion of structural framework. The garage will have “attic” framed trusses with a room inside. The roof will be the crowning touch, with several different pitches and “broken” pitch overhangs that start at one slope, then break into another. Look at the quality of the Framers Series lumber, which is southern pine selected density. It has a mold inhibitor on it, is grade stamped and has the crown clearly marked on each piece. There is a two year warranty on sheet rock pops, which constitutes two cold and warm seasons in which the structure will settle. In addition, it is guaranteed not to warp, twist or bow. This is truly a value compared to the alternative, conventional spruce pine fur which is commonly sold in lumber yards. This is a “green” product, yields very little waste, and is unparalleled in quality and aesthetic appeal. I will try to update this house in different phases to give a perspective of the start to finish. Keep checking for updates…