Best way to insulate a rowhouse flatroof one room at a time
Hi Martin and all, thank you for all of the great information everyone has made available as I have found much f it to be quite informative, and possibly saved my roof from the idiot mistake of almost dense packing cellulose in the 14" cavity between my plaster and lathe ceiling and my roof.
My question is, as a new first time homeowner, I am trying to rehab each room in the house, room by room in the interest of being able to live here while doing so, which in turn means as I near the end of the room I am currently working on (the first one) I will only have sprayed CCSF on the underside of the roof sheathing in a 9'x 13' area of a roof that is 18'x40'. The room I am finishing, is right next to the bathroom that has no exhaust vent (yet), and is at the low point of the roof. Further complicating matters, there is a chimney remaining from an old wood burning stove (true for all three bedrooms on the 2nd floor) that needs to be, and will be removed when I can afford to re-roof the house (the current roof is in moderate, at best condition and almost 30 years old).
I have framed the closet to surround the chimney on the two exposed sides in the room, the 3rd side is to the exterior wall, and the 4the side will be accessible by removing the plaster from outside of the room in the hallway in order to remove the remainder of the chimney and turn that void into another closet. It is clear that at some point there was rainwater entry here from a failed seal around the chimney.
The cavity between plaster and lathe and the roof sheathing in the rest of the house will remain untouched for the next few months, and the only other thing I will do shortly is install the bathroom exhaust, as there is no exhaust system in the house, and the cavity b/w the ceiling and roof is un-vented. The balance of the ceiling is FAR from air tight as it consists of collapsed plaster (from what appears to be a leak about 15-20 yrs ago) covered by drop tiles (first timer lessons, thank my inspector.)
Currently it is a hot roof (likely multiple ones layered) onto what appears to be galvanized sheets (I can only observe what is visible between the planks) onto planking secured to joists on 26" centers.
I intend to apply 2" of CCSF to the sheathing in this room only (for now), apply drywall, and then dense pack with about 12" of cellulose, with the exception of the void surrounding the chimney which is surrounded with 1.5" rigid board, sealed with OCSF, with a plastic sheeting vapor barrier on the inside of the studwall (b/w the wall and the chimney), and dry wall between the studwall and the rooms "conditioned space"
I'm sure many are cringing already, but the house was built in 1890 and is my problem to solve for likely the next 30 years so I'm going to do the best I can with it.
I do intend to put on a new roof in the next year or so when I get back on my feet, and will likely do an additional 2" of rigid foam in between the roof sheathing and a rubber membrane. I hope to address the ceilings/ underside of roof sheathing with the exception of chimney voids to be dealt with post roof) about one room every 2-3 months ( so should be able to complete the ceiling/ inside insulation by June 2014.
I wanted to confirm with those of you significantly more experienced and knowledgeable then I that I am on the right track, and not about to do something that is going to cause a structural failure in the roof 5 years down the road. I wish I could hire a pro, but honestly my resources are in a manner that I can either do nothing and continue to heat and cool (or be incredibly uncomfortable) the city of Philadelphia, or roll up my sleeves and do the work myself. While I have experience as a carpenter, I certainly am in foreign territory when it comes to energy efficiency, dew points and the like.
Hope to add a plan view dwg and center section dwg along with some pictures to this post, but just cant do so right now.
Hope everyone has a good holiday.
Posted Thu, 12/19/2013 - 15:26
Other Questions in Energy efficiency and durability