Second Floor Trusses and an Oops!

From August 27 - 29

Long ago, Vince decided that he wanted to have a chase between the first and second floors to hold the services for the house, like the ducting, wiring, and plumbing. In this case, a chase is a rectangular housing for mechanical things and not the same thing as running in hot pursuit after something else that is running away. The important thing about the chase is that it is a convenient and available passage that prevents awkward placements for ducting and pipes and gives back a tremendous amount of flexibility when designing the floor plan. The concept of a chase between floors works only if there has been a careful assessment of how large or small the systems of the house really need to be. There are two types of calculations to be done: One is called a Manual J Calculation, which analyzes the heating and cooling loads for residential use. The second calculation is called a Manual D, and it determines how much and how big the ductwork for the house needs to be to accommodate the Manual J assessment. Vince sent the details of the windows, the insulation, the roof, etc. to Steve Jenkins, a mechanical engineer who did both sets of calculations, spoke with Johnny Ghee about the truss design and also will work with Jesse Owens, our HVAC project manager at Norris Mechanical, to plan the installation. A lot of people consider the calculations to be an extra and unnecessary step, but these numbers work together as an important and valuable tool for saving time and money and also for providing a comfortable home. We are trying to be energy conscious, both because it is good, green thing to do for the planet and also because we want to have a sustainable lifestyle as we get older.

For this house, the chase was designed into the second floor trusses, which have a rectangle in the center and angled webbing on the sides. The rectangle is 20” high and about 22” wide. The most important aspect of the installation was to be sure that the trusses are perfectly aligned, so that the hard ducting can be fed into place. The second floor trusses, like those on the first floor, lay east to west and span the width of the house. They sit on girders that run north to south across the length on the house. The second floor trusses are taller than those on the first floor, and they include a series of 11 four foot trusses that run the length of the space over the hall. Jesse warned us to be sure to check the truss alignment, a suggestion that we took seriously. Vince and I headed up to the house to eyeball the trusses on Saturday afternoon. We weren’t able to climb up into the house to look closely, but it was obvious that, sure enough, there was a big “Oops!” in the truss alignment. Vince said a lot more than “Oops!” but thankfully the problem is solvable in the field. Vince and Karl went back up to the house and examined and measured everything, and it turned out that only one big truss was flipped, but all 11 of the short trusses had the interior rectangle nearly five inches off. The error was in the manufacturing, not in the installation, but the surprising thing was that no one noticed it. Since there is no elbow room in the chase, those trusses will have to be altered in the field according to Johnny Ghee’s plans for the repair, and they will be given an engineering stamp of approval for supporting the necessary loads. The flipped truss on the end can’t be moved, but because it is on the end it is acceptable to remove the webbing, put the ducting into place, and replace the webbing. Problem solved, thankfully, but it was good to find it before too many other things were put into place. As Karl would say, we are all flawed humans and mistakes will happen, but I am learning that finding them early stops one mistake from becoming a series of multiple problems and compensations instead of just one problem.

My son, Zach, and grandson, Ayden, were here at the beach last week. I took them up to see Grandma’s new beach house on Wednesday morning, and Ayden was thrilled to watch Stuart lifting the trusses up to the second floor with the forklift. Ayden is three years old and loves all things related to heavy equipment. He has watched all of the raw footage of any video that I have taken, and he knows the names of each guy who work with the trucks. I told him that the big truck with the crane and the augur belonged to Duncan, but that Steve was the man who worked the truck, and Ayden knows that Stuart drives the forklift. On Wednesday night, when it was time for a bedtime story, Ayden and I made up our own story, and he made sure to include the guys whose names he knows as the folks who save the day. His little story is fun and quite wonderful, so I am including it here. Like Ayden, I am hoping that the men with the trucks will make my dreams come true and save the day! I think they will, don’t you?

Here's the little video showing the trusses going up. Ayden's story is in the next post.