Thank you for your response! I'll try to answer your question below define poorly installed batts. We have gaps between bats AND some sections where batts don't lie flat on the attic floor. Builder's insulation subcontractor originally tried taking the 9inch thick batts and slicing them in thirds (like slicing bread) to make three 3 inch batts that he thought I would accepts as the correct insulation! These were laid between joists. When I caught onto the subterfuge, he claimed that he hadn't been aware of the cheating but would make sure the insulation was done over properly. Instead, he allowed them to just drape 9 inch batts perpendicularly across the joists over the top of the 3 inch thick slices. Because it was very difficult for me to get up into the attic (attic ladder hadn't yet been installed), I trusted builder to make sure it was done over correctly. It wasn't and it is a MAJOR mess. To the extent that we are able to reach the batts, we intend to pick them up and reposition them correctly or just take them out. But there are areas behind the heaters that the only way to reach is by crawling over the heaters so we were hoping we could just blow insulation into those areas without first repositioning (or taking out) the batts. Guess not. do you have service platforms around the units? there should be a 3' walkway to and around units for service. The units both lay beside a platform so it is easy enough to get to one side but there is no walkway "around" them. check & see if batts were installed under unit platforms and walkways...water heaters too if they are in the attic. there are batts between the joists that the units sit on. Whether the batts extend the entire distance under the units were only put in place at the very edges to make it look like underneath the units was insulated, I honestly don't know. Will have to pull a couple out to check. Thanks for suggestion. understand that under heating system you'll only have R-30, which is code here in La. how about in Tx? at max we put R-38. We're outside of a code restricted area but under our contract the builder was supposed to have built to meet code requirements of the nearest major metro area which, at that time was R-30 in the attic. New recommendations for this area are R-50. I'm not sure what the nearest metro code now requires. I don't know what value you plan to insulate to... what is your goal? and what is the purpose of the added insulation? We would like to get as close to R-50 as possible even if some parts of the roof are only insulated to R-30 or lower. Seems like it is good to insulate as much of the attic as possible to R-50 to reduce heat transfer between attic and living areas. I find it is usually air leakage into the house that people try to solve by adding insulation. it never works unless the new insulation both insulates and air seals. (foam ins) with propane you'd have to add combustion air if you foamed the roofline. many insulation companies don't understand how to do this...nor to hvac companies. air sealing is easier with batts than with any other insulation. move the batt...do the air sealing... put the batt back. Not sure I totally understand you here. Our attic is not sealed. We have ridgeline vents and soffit vents. So far I haven't seen any signs of inadequate ventilation in the attic and I know that we need to leave space for air to circulate between soffit vents and ridge vent. We intend to be sure to leave the baffles in place and not block either end. As for air infiltration into the house, the house is pretty tightly sealed. We fired the builder before the interior walls were insulated or sheetrocked and I personally went around with cans of spray foam filling in every crack where I could see light coming thru the exterior shell. All the gaps around exterior electrical plugs, etc. Then we hired a different insulation sub to install the wall batts and I checked every piece of it before sheetrocking started. So, the house is tight. do you have recessed lights? IC or ICAT? the IC lights are a big leakage to living space. We do have recessed lights. They are ICAT. (I've checked). were ducts mastic sealed? or just duct/foil tape? returns in attic mastic sealed? I don't know. What should I look for to find out? And if just duct/foil tape sealed, what is the proper way to fix it and is this a job a homeowner can do or will we need to hire pros? I'm assuming this should probably be done before blowing in additional insulation so one is not having to tromp over and thru the blown in insulation to reach the ducts to work on them.

Thanks for the replies. First, I will rule out the building the floor up - the bedroom floor has 1.5" subfloor+linoleum tile + 6 year old laminate planks. We would like to keep the laminate floor at this time, plus furring the rafters down will already eat up some valuable headroom, good thought, though. I don't know too much about GDO rails. I will need to look at that a bit. As far as the insulation, I am thinking about this - 1). 1 to 1.5" vent channel, probably constructed with 1/2" or 3/4" styrene with spacer blocks to form the channel (about R-4 for the vent chute) 2). 2-R15 High Density fiberglass batts (7" total thickness, R-30 total) This will require about 2.5"-3" of furring strips, laid on top of the rafters & plywood gusset plates to attach on the sides 3).Either 1" or 2" Extruded polystyrene sheets (R5 to R10) over top of the furring strips, with taped seams. Total = R-39 to R-44. About Number 3, I am undecided. If I use 1", I think I could use about a 2.5-3" drywall screw. With 2", I may have to use 1x2 or 1x3 straps laid transverse to the rafters to attach drywall. Maybe I will need the straps with the 1" foam as well, I don't know. Thoughts on this?

No roof can be "flat"; it must slope at least 1/4" per foot and sometimes more to avoid ponding in later years. A standing seam metal roof that can slope 1" per foot needs to be machine crimped as recommended by the manufacturer. You should already be in contact with a manufacturer's rep to get advice for their system for this design. For a conventionally fastened seam design the min slope is usually 4 in 12. I would use full coverage Ice & Water Shield (Grace only) under any metal roofing system Metal will look better if you can actually see the roofing from any place important. The advantage of EPDM single ply roofing is the seams might be 20 or 30 ft apart instead of 18" and it's cheaper and easier to repair. On top of rigid insulation metal would be supported on spaced strapping or continuous sheathing and fully-adhered EPDM would be supported on a wood fiber board. It generally helps to see the house design since so many aspects of exterior design are determined by appearance. I would be concerned with the roof edges and where the roof drains. It is unwise to design one aspect of a house at a time. I can't believe your architect and builder aren't doing this for you.

A very sensible comment mtvhike - you are right of course. According to your big picture view, I have three choices, replace and reframe the roof, which I would only do, if I were going to add a third floor addition, or use the foam, save the money and live with it, or use a reduced amount of insulation and pay higher energy prices. Every person might make a different choice. I am still considering using some rigid foam board in a 3-4ft section along the lower part of the dormer roof where it's impossible to get much else in that small space and using rock wool everywhere else. I'd also have the option of lowering the ceiling, but I don't believe I'd have enough headroom. I also prefer wet plaster to drywall. All our first floor walls are that and it is a quite noticeable difference in quality and longevity. A previous owner used drywall on the second floor. We have some added plastic pipe in a couple of places and I hate it. I'm not familiar with the difference between Romex and BX. In some cases it may be that the difference in using one product over the other, is for reasons of quality, but in others, it becomes known after something has begun to be commonly used, that the newer cheaper material has health consequences. In those instances, it's more than just 'taking a principled stand' to me. Some people feel the health risk is a reasonable one and doubt there is enough exposure to be concerned. To me, when it gets to the level that homeowners are bringing a class action suit for health problems caused by using the product, that's enough evidence for me to feel the risk is not reasonable. You do see my dilemma and I appreciate your comment.