I've been helping a friend fix up an old Sears kit house. She needs a new roof and is scheduled to have one installed in the spring. At the present time, the attic is unfinished, but she has long term plans to convert it to living space. The rafters don't come down to the floor, the wall comes up 3'-4' from the floor and them meets the rafters. There are no soffit vents or ridge vents. Two of the windows have vent panels. There was some kind of loose fill insulation on the floor which the former owner started replacing with fiberglass with a paper backing. In some places the paper faces the down, in others it's up. As I understand it, the paper should face down in an unfinished attic. The roofer is planning on installing a ridge vent. Is this wise if the attic will be finished? Also, will it function without soffit vents? Even if she does not finish the attic soon, I think she should lay OSB or plywood down to have a workspace, (her basement is damp, so a workbench down there is not a good idea). Would this adversely effect the proper functioning of the attic in terms of insulating/venting, etc? BTW, how do you get paragraph returns to show up in your posts? I've tried the "return" key and the "enter" key and both disappear when I hit submit.

vented attics don't work, period. Case in point is: go in the attic in the summer - most likely it will be 120F-140F, so, not venting enough. Any air that moves through the attic carries a certain percentage of humidity with it. This humidity ladden air gets trapped in the fiberglass (bad, bad)! Fiberglass compresses with time and looses its R factor - bad. And the attic is still hot in the summer and cold in the winter.

My suggestion would be to build out the knee walls to 5 1/2 inches (the knee walls are build with 2x4?) Rafters are 7 1/2" in depth, right? Don't install a ridge vent. Use sprayfoam (polyurethane or incenene or soybean) the fill the rafters and the knee walls. Make sure you provide vents/returns for the future. Now you have a finished un-finshed attic. I would put the air-handler up there if it is not already up there. Since your air is now conditioned less load for your air handler and duct work.

It will be a long time before the attic is finished– my friend has a very limited budget. Right now the roof needs to be shingled and it's scheduled for the spring. After that she'll probably need a new oil burner. Then there's the basement which has water problems.

There is no air handler. The house was built in the 1920's. The heat is hot water run through cast iron radiators– and she likes radiators.

I can't see turning the attic into conditioned space till she is going to finish it, since doing so would near double the space she needs to heat.

Double check that the attic floor joist can handle the live and dead loads of a living space.

Good idea. I'm pretty sure they are. The house is an old Sears house, sold as a kit through the catalog. I think they were designed with this sort of expansion in mind.

This may be a moment of opportunity:  2" of EPS or XPS foam insulation over the entire roof (including overhangs) with a nailing layer of OSB + roofing felt under standard roofing materials, then stopping all venting will fix a WORLD of ills (ice dams will be next to impossible) while adding ~R10 to the roof structure.  Shingle manufactureres will grouse about it voiding the warranty blah-blah, but at worst it takes 10% off the life of the shingles (indeed, orientation/angle & color of the roof or the climate region make a bigger difference than vented/unvented.) Staggering the seams of the OSB and XPS will make it air-tight by design, but mastic-sealing the seams of the EPS makes it virutally leak-proof too. (If the shingles leak into the OSB it may take awhile to detect, but repairing it isn't nearly as expensive as if it messes up structural stuff.) 

If she gets at least that done on this pass it'll be possible to  turn it into a truly high-performance structure by insulating from the inside with other materials later.  NOT doing it at the time of re-shingling makes it more expensive later.

There's a huge amount of verified & tested info on the subject of vented/unvented attics on the Building Science Corporation (BSC) website, as well as some recommended climate-zone specific stackups & recmmondations.  Start here:

http://www.buildingscience.com/documents/digests/bsd-102-understanding-attic-ventilation

DO download the BSD document before proceeding- it may change the design or the order in which you proceed.

The stack-effect of multi-story structures increases with height. The most important places to impede air infiltration losses (40% of the heat loss in MANY older houses), is to seal the attic, and the basement (particularly the sill & rim-joist, but also plumbing & electrical penetrations into the first-floor.)  Even if she NEVER builds out the attic into living space, the EPS/XPS + OSB nailer and converting to an un-ventilated design will be worth it.  Fulling air-sealing between the living space and attic is nearly impossible, but unventilated attic designs pretty much stops the infiltration loss in it's tracks. And even in a basment with water issues, insulating & sealing the sill & rim joist and insulating to at least below the frost line to R10 or better with plastic insulation will be worth it as well. (Avoid batts or cellulose in basements, particularly wet ones.  BSC has a lot of onling material on insulating basements & foundations as well.)

that BSD link is very informative, thanks for posting it.