I have an old wood frame house we plan to move back into to retire, and will rebuild the upstairs due to a fire damaging half of the upstairs (renter's carelessness). The house is a straight story and half with a gable on both ends with louvers in each end at the peak for ventilation. The upstairs has knee walls for the side of the two rooms and bath, the entire length of the house except for the stairs. There is a horizontal ceiling about 4 feet below the apex.

I built half of the upstairs myself, making a room about half the length of the house. The other half is what burned. I'm not sure I did my part right, and now when I rebuild I want to do both right. In insulating the rafter part of the ceiling (from the knee wall to the horizontal ceiling) I packed batt insulation into it, and used T1-11 for the entire ceiling (an old farmhouse and we liked the look). But, the only ventilation is in the gables and I am concerned that if I insulate well for the entire length of the house that way there will be no ventilation for the attic beside the rooms. AlsoI am wondering if that section of rafters being insulated like that may be bad for the roof sheathing (Metal roof over felt over solid board decking).

I wondered about putting pvc pipe in each rafter section to give a flow of air from side attic to upper attic ventilated area. I really don't want to use end wall ventilation on the side/lower attic (beside the rooms). The room I built upstairs was really tight and I'm sure the tightly packed insulation kept the fire from bothering that end of the house, and the metal roofing kept it from going through the roof so the fire did not spread. I just wonder if I might have been headed for problems caused by incorrect insulating. I am using batts with vapor barrier stapled to inside structure on walls and ceiling behind gypsum (side) and T1-11 upper.

Thanks for the advice.

 

With gable louvers it's one in, one out, so you'd want to free up some space under the roof deck so the air could travel freely from end to end.

Insted of pvc, why don't you try rafter-mate panels? Just place it between the roof decking and the fiberglass batts. Do it for the entire run of the room's ceiling so the air has a straight shot over it.

 

Good thought. From what I see online of the Raft-R-Mate panels from Owens corning, it looks like they would allow air along the decking, which solves 2 problems. I'll have to measure to see if my rafter wall/ceiling is longer than 3 ft, and if not that looks like the way to go.

 

Home Depot and lowes have the foam rafter vents that you need up there before the insulation. So it dont touch the roof boards.

ED