Posts Tagged ‘Mechanical Chase’

The Duct Chase

June 16th, 2011


Part 5 of The Duct Chase 6_29_11 The showcase of this house, the radius ceiling, was shipped yesterday by First Flight Stairs and when I went by this evening it had been installed. It runs the entire length of the second story of the house from the entry to the rear wall, aligning with the radius windows in both, yielding a stupendous view of the golf course behind. The homeowners were onsite and commented how it was just as they had envisioned, a gentle curvature that was not overstated. In the close up photograph of the ceiling you can see the silver reflected coating of the 5/8″ Tech Shield sheating above the top chord bearing trusses forming the roof of the two story section. As mentioned in previous posts on this website, this is an effective and economical method of saving energy costs which requires no additional labor for the installation over standard sheathing. The radius ceiling was shop built from 3/4″ plywood for the ease of onsite installation. In addition, it had been routered, milled and planed for consistency. As talented as Wayne the framer is, he admitted to me it would have been very difficult and time consuming to acheive the finished appearance and accuracy this ceiling had. He had been sheathing the right side of the house first and was able to slide the ceiling in place from the left side while he had room prior to construction of the conventionally frame open section. As planned, this ceiling spaced 16″ o/c can be attached to the top chord bearing trusses above for ridigidty while only carrying ceiling load. The top chord bearing truss carries the live load and construction weight, such as the sheathing, 30 lb.felt and shingles above.



Part 4 of The Duct Chase 6_24_11 Shape and form are taking place as sheathing is being applied to both the floors and roof. The second level is now navigational and you can walk from area to area. The right bedroom shown is floored as the piggybacks on top were being set in place late Friday evening. Both “kneewalls” have HVAC areas built into them that will be one step down from the bedroom floor. The large framed window was positioned close to the rear than expected, as not to have an obstructed view from the roof towards the front. There will be a bathroom towards the front on the extreme right side that will benefit from the attic area floor being open webbing to allow plumbing pipes to travel through. Wayne’s crew will move from right to left completing as many tasks as possible before moving on. Next week the radius ceiling will be attached to the top chord bearing trusses in the center section, as Wayne plans to attach them by sliding them from the left to the right. From the right side elevation picture, you can see a very long (42′-0″) LVL (Laminated Veneer Lumber) ridge beam towering over the entire structure which hangs from the right side trusses to the left wall. Wayne will used this to conventionally frame the left side bedroom roof which is perpendicular to the garage attic frames. Our design has allowed for intermidiate bearing for the rafters (over 22′-0″ long) which will be fingerjointed SPF (see the Energize and Accessorize post) so as to prevent the clear span floor trusses underneath from roof loads being applied. On the rear will be the 7′-0″ deep girder with the doorway built in and the front has a floor girder which transfers the load through to foundation where two thickened footers are in the slab below. The image of the garage bonus room is now completely sheathed where once there were large gaps between the floor trusses, now occupied by attic frames. The one remaining space is for a large 8′-8″ dormer, which will be framed in between two three ply girder trusses on either side. Wayne and I conversed about the felt paper being applied. He uses 30lb felt versus 15lb felt mainly because of the 15lb felt ripping and tearing simply in the process of walking on it, much less if a strong wind whips up. I hope to get over next week to add to the resume of radius ceilings as I am sure this will be the most striking of any we have supplied up to this point. They are completed in our shop awaiting shipment to the job.


There is a new page added for Ford Fuel + Propane a commercial offering here at Timberology, which we don’t get to say very often, like not till now at least. Very tall walls for the second story warehouse section which will be interesting to see and follow. Also, I am working on what I hope to be a great blog on a piece of history. It is a good story because history wins, and the present has to be satisfied with blending in with it rather than taking over. How’s that for a teaser?



Part 3 of The Duct Chase 6_20_11: Nothing is quite like the setting of roof trusses to gain a perspective of the framework or “bones” of the structure. Today in the sweltering heat of 103 degree temperatures, Wayne and his crew braced off the attic frames as they were flown into place by a local crane service. Temporary and permanent bracing are essential to the safety and welfare of the crew and the surrounding area. If left improperly or unbraced, one slight of wind can cause these massive structural pieces to domino causing damage and injury to everything surrounding it. The most effective form of permanent bracing is actually the sheathing itself, in this case 5/8″ Tech Shield (see Thistle page for more information on this product). One of the first places I photographed was the same area at the balcony floor trusses, where the duct now winds itself from the left side to the right side. The attic frames have a built up 2×10 bottom chord to match the depth of the floor trusses at 18″. More importantly, the 24″ HVAC duct runs through the 3 1/2″ wide floor trusses and into the 1 1/2″ wide attic frame bottom chord, creating a consistent chase run. When looking at the attic frames keep in mind the “peaks” are not yet piggybacked (see Shaftsbury Glen page for more details) so they are currently flat on top. Over the right side there is a room size of over 21′-0″ wide and a ceiling height of 10′-0. Look closely at the photo showing the area to house the HVAC unit itself. You can see an angled piece behind the kneewall allowing for access and servicing of the unit once the floor is sheathed. Then comes the same shot over the garage from Part 2 now with the open areas filled in with attic frames. Again the bottom chord has a 24″ duct to align from the front to the rear, through the floor trusses initially set there from Friday. Now you can see why the sheating was not completed as the roof trusses had to be set in place before the sheathing was continued. The garage bonus room is over 17 feet wide with a ceiling height of 8′-0″. What you can now see is a plan starting to come together. What is not visible is the bidding process, the shop drawings sent for approval after the designers review plans and generate them, the sealed drawings reviewed by a structural engineer, the guys in the plant that cut and build the trusses, the delivery guys who put these trusses loaded on 48′ roll trailers on the road and to the jobsite. Nope, when you drive by and look you can’t see those processes. Just like what happens backstage at a major Broadway production, if the audience applauds, it is because all the processes worked seamlessly behind the scenes to make it happen. The production company is what puts the people in the seats though, just as our production staff works silent and tirelessly behind what you see at this site to make it happen. The finished product is the cultimation of a plan coming together, the pieces of the puzzle in place, and hopefully a satisfied customer who is rewarded for putting their confidence in this system and our people to do what they wanted.




Part 2 of the Duct Chase (the next day) 6_17_11: Man, Wayne and his crew are keeping me busy trying to document this house for you. The picture of the trusses on the ground are top chord bearing trusses designed for the center 2 story section of the house. They have 2×8 top chords and function as advertised, on the top chord. This allows the “collar tie” or the flat section where the truss is webbed to be 36″ above the plate line. Above the balcony, through the entire ceiling running from the front entry to the rear Parallam Column supported wall illustrated yesterday, will be a radius ceiling attached to each truss spaced 16″ o/c. Yes folks, we will have another prime display for the First Flight radius ceiling page. Our shop is currently working on producing the arched 16′-4 1/2″ total span masterpiece to be installed against the trusses shown here. Another point of interest we are witnessing at this stage of construction includes the 3 ply girder which is built with a doorway leading into the HVAC storage area. You can see this door opening just to the left of the ladder in the girder photo. The girder is built 7′-0″ deep and forms the wall where conventional rafters Wayne’s boys will bearing running perpendicular to the garage. This girder is essential in order to disperse the rafter load to the exterior walls and keep exteraneous roof load off of the floor trusses, which are designed to clear span the distance from wall to wall carrying floor weight only. It is in the position to be the “kneewall” of the bedroom at the same time. Dual roles are so intriguing from a planning standpoint, don’t you think? Anyway, in the other picture of the garage floor trusses, observe the large gaps left between the floors and the fact the sheathing is not yet completed. This will be important when the crane arrives on Monday to set the remainder of the roof trusses. I took a photo of the balcony floor trusses in which you can see a 24″ space has been left between the center trusses. This too will be an important point when the crane sets the trusses on bedroom number 4 on the far right at the end of the balcony. The trail of the duct chase will be increasingly more obvious when the story and 1/2 roof truss attic frames are paired against the floor trusses shown here. Remember to tune in early next week as the mystery unfolds right before your eyes, exclusively here at Timberology, where mysteries don’t just happen; they happen because we withhold information purposely to make them happen. Would you have it any other way? Well…. would you?



Part 1 of the Duct Chase 6_16_11: An interesting story and 1/2 house being built in North Myrtle Beach, SC, will serve as an excellent illustration and lesson in how mechanical ducts can be intregrated into a component floor and roof truss system. I am going to have several posts added to this one to show how planning is essential to creating a successful mechanical flow. To explain what my expression “story and 1/2″ means, when you see a roof on a structure that is steep, chances are that upper roof area is housing habital attic space. Normally, two story houses have a 1st story wall clearly separated by a floor with an additional wall on top of the floor constituting the 2nd story (or level) with the roof on top of that 2nd level. The story and 1/2 has a second level, but the level is built into the roof which sits on top of the 1st story. This style of building, although very aesthetically pleasing, creates challenges in getting HVAC (short for heating, ventilation, and air conditioning) ductwork throughout the house. Here we are using 18″ deep floor trusses, spaced 19.2″ o/c*** (on center) with open web design to aid in wiring and plumbing fitting through the webs as well. They have a duct chase in the center which is 24″ wide. This means the HVAC duct has an opening to travel unimpeded from point A to B within the floor system. As this house progresses, you will be able to see how roof trusses can be constructed to constitute both the floor and roof system simultaneously, while having a chase in the center to match the floor system’s chase. All that and a bag of chips as you might hear in popular culture lingo. Where there are true two story walls, the center section of the house has 10′-0″ 1st story walls and 8′-0″ 2nd story walls with arched segmented windows in it. These massive walls are supported by parallam columns, which are the “big fat yeast rolls” of construction. These columns are designed to carry loads from the LVL headers to the foundation with ease. All I can say is awesome. Watch this post for the future (not too distant, like 1 more week) to see how the attic frames are designed with the duct chase in mind. As in meditation, it is all about the flow of energy…{***Ok kids pull out your tape measure and look for the diamonds. They are specifically located on th 19.2″ o/c mark. If you multiple 19.2″ X 5 you get 96″. Why is this important? Because a piece of tongue and groove plywood is 4′-0 x 8′-0″ (or 96″). So when you get to the 5th floor truss at 19.2″ o/c you have a 3 1/2″ surface to nail the plywood. Structurally more sound than 24″ o/c (4), less costly than 16″ o/c (6), both of which equal 96″. And you thought you didn’t get anything out of reading my posts.}


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