I have my first Energy Star home that has sprinkler piping installed in the attic. The pipes run about 6 inches above the drywall. The sprinkler company says there must be an insulation void between the ceiling top and the piping to avoid freezing, so the insulator placed fiberglass batts over the piping to keep the blown fiberglass away from the pipes, which will leave (roughly) a 6-inch by 24-inch air gap directly above the drywall at each pipe run. This, of course, violates the Energy Star insulation-to-air barrier alignment guideline. I don't have a good solution to offer, but I'm wondering if removing the batts and blowing the insulation (R-38) directly around the piping, which would leave roughly R-18 over them, would suffice. Has anyone else dealt with this issue yet? This will be the norm for all new homes in PA.
I believe the Sprinkler Company has a problem not stated. NFPA does not allow any thing to rest on a sprinkler pipe. Blowing insulation around the pipe would not allow the required periodic visual inspections. Resting batts on the pipes also prohibits visual inspection and additionally cause the potential for the pipes to deflect. Deflection changes the water flow - think flex duct bends etc.
With a wet sprinkler system install in the attic, you are pretty much stuck with installing the insulation on the roof deck. The sprinkler has to be able to spray water on the roof deck as well as below. Prior to my certification as a HERS Rater, I was administrator of a medical facility that was sprinkled. The batt insulation was installed on the roof deck. It sags, looses contact with the deck, drops out, lands on sprinkler pipe and other places you don't want it.
How high is the attic space? I am slightly surprised there are not sprinkler heads along the roof deck also.
Since there is little choice except to include the entire attic within the thermal envelope - I believe the long term solution is to foam the roof deck
Your install is subject to local fire inspection. I would keep all of the above in mind, and visit with them. Start at the Fire Dept. They like tight houses. Explain how you do tight shell, and see what they say. Then approach the actual building inspector.
We run into this problem a lot in North Carolina. An alternative to foaming the roof deck & gable ends is creating a horizontal boxed chase for the sprinkler lines. Typically, our builders keep the top of boxed chase lower than the ceiling insulation so there isn't a need for a 6-sided wall assembly. The box (built with drywall, plywood, Thermax or equivalent) is air sealed with an appropriate material (mastic, caulk, foam). I also recently found this Literature Review from the NFPA to acknowledge that there is a conflict in sprinkler freeze protection and ENERGY STAR. The article also offers a variety of solutions. http://www.nfpa.org/assets/files//pdf/research/rfsprinklerinsulatio...