Commercial Attic Space Over Ducts

They live in a townhome with no attic or basement or crawlspace of any kind.
Commercial attic space over ducts. Additionally some of the attic space is over an outside deck while other sections are over the house s interior space. Obviously this means a lot of ripping and tearing etc. Why put the ducts there. Part of the unit is inside and part is on the roof.
They have been told that they need to replace all the ducts. I lowered soffits around room perimeters. Shown below is an example of what not to do a grille cut into pull down attic ladder and an example of the right way to add a vent a register in the ceiling of garage that connects directly to a roof vent via a metal duct viewed from the attic. When determining how to insulate this attic space various assemblies were taken into consideration and a hybrid combination of vented and unvented attic space was planned.
Combustion air also called make up air can also be provided by a vent through the wall. Ii lowered ceilings in hallways. All the ducts are in the attic. Your attic will probably be over 100 hotter than the crawlspace.
Furnaces ducts and air conditioning ac equipment run throughout the attic spaces on all levels except the dormers and the space over the outside deck. Looking at the cooling side only the additional load would be. R 8 duct insulation 5 227 btu hour. The duct insulation should include a vapor barrier cover.
My parents own a home about 40 years old and there is black mold coming from the a c ducts. The 1 800 square foot brick ranch in climate zone 4 dates from the 1960s but the previous owner installed both a furnace and ductwork in the attic just four years ago. Duct sealing duct and pipe insulation and location lighting fixture schedule with wattage and control narrative location of daylight zones air sealing details scope construction documents section c103 the building thermal envelope shall be represented on the construction drawings. Iv conditioned attic and more.
You can get the air handler and ducts into conditioned space in several ways without needing a basement or crawl space. Use metal flex or fiber board ducts that are insulated to code. For homes with ducted heating and cooling systems the best place to locate the duct system from an hvac performance standpoint is within the conditioned space of the home either in dropped ceilings or between floors or in a sealed and insulated basement crawlspace or attic. Ted has more than a few cobwebs in his attic.
There can be moisture issues in the crawlspace but i would deal with that before choosing to put the ducting in the attic. According to rightsuite the software we use the supply ducts have about 560 square feet of surface area and the return ducts 101 square feet. If the ducts must be located within a vented attic one option for protecting the ducts and helping to minimize heat transfer between ducts and the unconditioned attic is to lay the ducts on the attic floor and. Iii special trusses that create space below the unconditioned attic.
If the ducting is not sealed well and insulated you will have plenty of problems because of the high attic temperatures.