The two biggest positives of using floor trusses are the greater spans and open spaces for running HVAC and plumbing through them. You may not have had to remove the floor mounts, but if you have, it is best to go through and mount them to the sub-floor before you start hanging the duct work. Through-Penetration Firestop System. But let’s say there is a change on the job site and the truss company was not informed (Which never happens right?) But since the trusses are wider that other (more traditional) options, it did cause changes in the specs on the floor plan. I would like to run wiring parallel to the 2x4s (perpendicular to the trusses). The second photo shows running HRV ducting and even residential sprinkler piping on the warm side of the ceiling. The resulting chase is variously called a raised HVAC coffer and an inverted soffit. While ducts easily run between floor joists, it can be very difficult and sometimes impossible to run ducts across joists. Hoping that a ducted mini split will get the job down … Less energy will be lost through ductwork if the ducts are … Like a roof truss, floor trusses are created through joining standard lumber, typically 2x3 or 2x4, with metal connectors. The resulting, engineered product is a long-spanning floor joist - about a half to two times taller than a typical 2x10 - that is able to house HVAC ducts, plumbing and other service lines within the floor assembly. At the roof itself, use high quality vents made from a durable material with a flange that creates a watertight seal. It’s possible to order special roof trusses, called plenum trusses, designed to accommodate a duct chase near the attic floor. Ah, so many choices. Be sure to avoid floor joists, and move the vent location slightly if joists are found within the marked areas. Penetrations by ducts and air transfer openings of a floor, floor/ceiling assembly or the ceiling membrane of a roof/ceiling assembly shall be protected by a shaft enclosure that complies with Section 708 or shall comply with Sections 716.6.1 through … The ductwork runs in-between the sup-porting timber trusses or joists, depending upon the floor system, until the ductwork reaches its The hole cannot be larger than one-third the depth of the joist, so the maximum hole size for a 2×12 joist (actual size 1-1/2 x 11-1/4 in.) I am building a 2 story house with a central hall plan. The most common size duct used is 14-in. When possible, avoid running wires in the ceiling against the joists (red wire above). Where this insulated duct work runs through the 2nd floor … If you want to design and install a duct system to create problems, the possibilities are endless. I've been taping the seams and joints of all ductwork with foil tape and then planning to insulate the ducts. A 2-inch hole may be large enough to accommodate wiring but for HVAC ductwork? “It’s more efficient. Still commonly used is the panned floor joist. 3 years ago ... day when a homeowner called me about wet spots on the ceilings. This would require a 3 1/2" x 10" right angle at the back of the range hood (the hood exhausts to the back), a 3 1/2 x 10 straight duct down through the stud wall, another right angle in the crawlspace, a transition to round ductwork (7 or 8) and then out to crawlspace wall. Top Chord BearingA floor truss support condition in which the truss load is transferred to the bearing or support through the top chord and 4x4 block end detail. Always insulate the duct to prevent condensation problems as the warm air will be potentially running through cold ductwork. It will give you an extra support. The basic rules of … Using floor joists as return ducts by panning can cause leakage because negative pressure in the cavity will draw air from the outside into the cavity through the construction joints of the rim area at the end of the joist cavity. With the ability to design chase openings for ductwork through them, this is a big advantage. not have the benefit of a floor system to run ductwork in conditioned space. Our floor plans account for this change. Nearly impossible. forming the top of the floor truss. All wood trusses are assembled with metal plates and provide openings for electrical and plumbing systems as well as running ductwork. On top of the 2x4s is metal roofing. Rehkemper & Son also provides the highest quality of wood floor systems available. Plenum trusses create a reverse bulkhead in the center of the attic space where ducting can be housed in an insulated area; “The plenum truss bulkhead adds only the amount of “inside conditioned space” required to house the ductwork by modifying the roof framing to create a boxed-in area in the otherwise unconditioned attic.” This can be done anywhere in the building. We offer manufactured truss "to specs" with the ability to vary heights and span needs. In sweltering cities where temperatures often blow past 110 degrees, installing ductwork on roofs and piping cool air through the oven-like atmosphere doesn’t make sense in terms of energy efficiency. Maximum Floor Joist Span - No. Pensacola PI. What you are describing is a running board. ft. area through this access hole. We hope the floor trusses will make the process easier down the line – running plumbing and ductwork and electricity through the spacing. Floor trusses are engineered complex webs of wood structure (similar to roof trusses) and should not be modified in any way without approval by the truss designer/manufacturer. in this particular house the ducts lay on the attic floor...running in the ceiling joist bays and insulators blew insulation over the ducts. I think a compact duct system is very do-able, because I have a walk-in closet nearby to place the air handler and the ducts won't have very far to go to serve all the rooms. Tips on Installing Floor Trusses. I want to put this bath on it's own 20 amp dedicated circuit. Click to see full answer. Today, though, let's focus on one particularly bad place to put a duct. diameter—plenty big enough for running cable!You can drill the holes anywhere along the length of the joist (first photo). Additional support for the floor joists is achieved by nailing the ends of the joists into headers. In a compact duct design, ductwork runs are reduced in length to yield a smaller and more compact duct system. Dryer Vent Through Floor Joist Plate Hole In Kitchen Sparkgift . With a two-story structure, you can create a central mechanical room with ducts to be installed in open-web floor trusses. Each joist must have a separate notch or hole … x 24-in. Cut all the holes in the trunk line where they will exit and run to the floor mounts. Description: In two-story homes, the space between floors is already used to some extent to run ducts, pipes and wires. Running Ductwork Through Floor Joists Framing Around Ductwork When Finishing Your Basement . HVAC contractors are faced with an improvised solution of under oraround but never through the beam. Case Closed Get Those Air Conditioning Ducts Out Of The Attic . Ductwork INSIDE AC space - Open Web Trusses. This gives us access to every room on that floor through side walls, giving the same results as running this stuff through the attic while leaving it all on the warm inside of the house with no penetrations at all into the attic. 2 Grade of Douglas fir and maximum span floor joists - imperial units; Rectangular Ducts - Commonly used Dimensions - Metric dimensions of commonly used rectangular air ducts in ventilation systems; Spiral Ducts - Dimensions - Standard dimensions of spiral ducts - Imperial units Instead, try to get right under the outlet from the basement and then run it straight up (green wire above). The floor joists will need to be a minimum 16” deep to accommodate for the ductwork. I have a master bath we are getting around to finishing on a 3rd floor. Locate, measure and mark all interior floor vent locations throughout the house using a vent template to outline the vents on the sub floor. It is a heated basement and plan to finish it into a living space. The relevant article is in 320.23.In Accessible Attics (A) Cables Run Across the Top of Floor Joists. ADVANTAGE: Floor Trusses. “You put the ducts in the envelope of the house, and it helps it keep cool,” Costello says. In a house that has an 8-ft. ceiling, these special roof trusses make more sense than site-built soffits. This helps prevent the floor squeaks mentioned above. Floor trusses have a distinct advantage for being mechanical equipment friendly. Floor trusses weigh less than floor joists, and some builders prefer them because the open truss design makes it simple to install wiring, plumbing and ductwork. is 3-3/4 in. Hi all, I am trying to study my lesson before talking with some HVAC pros about ductwork. Hi all. On top of the trusses are 2x4s (laid flat) running perpendicular to the trusses - 24 inches on center. Running drainpipes through floor joists is more complicated than running them parallel to the joists. In order to exhaust outside, ductwork must penetrate through the ceiling membrane of the fire-resistance-rated floor assembly, turn 90 degrees, and route horizontally within the rated assembly. In fact, I think it's the third worst place to put one. There is an insulated square duct that runs from the basement to the space now. Besides, how big of a hole can you put in a floor joist? Another great thing about floor trusses is the wide flange to nail through. When running wires from the basement to outlets on the first or second floor, be sure to avoid the flue and any HVAC ducts. Cut an access hole in the ceiling of the first floor in a central area to gain access to the ducts. 1 and No. ALL of the heating ducts run under the main floor between the floor joists. The roof has trusses 48 inches on center ( The trusses are pre-manufactures and made of 2x4s). This makes floor trusses a great option for home plans that are wide open. A specific field erected construction of an assemblage of materials designed to prevent the spread of fire through openings which are made in floors and walls to accommodate through-penetrating items such as electrical conduit, cable, cable trays, and metal and plastic pipes, etc. Wood Web Floor Trusses. Another option is to design in a chase, or continuous enclosure, to conceal ductwork. I've certainly written about a lot of them (as well as how to do it properly). Using floor trusses allows you to utilize eight-foot basement walls, as the ductwork is installed within the openings of the floor truss. Put at least one vent in each room, and more if the room is larger than 10 by 12 feet. It currently has an unfinished basement but I am in the beginning process of retrofitting this. I Joist Fire Assemblies Apa The Engineered Wood Association . Most installers report they can get to a 100 sq. Additionally, having the mechanicals and ductwork hidden within the web openings of the floor truss allows for the easy installation of drywall to the bottom chord of the floor truss to finish off a ceiling. This size fits just between most floor joists. Open Web Floor Trusses Application: This approach works only with two-story home designs. Get Price Installing ductwork for heating and air conditioning is a bit like putting together a huge three-dimensional jigsaw puzzle. When the 4x4 block length is extended, this is referred to as Mid-Chord Bearing.