Old House Insulation

I have a 100 year old house; no insulation; no soffit ventilation; the attic has blow in insulation and the roof as 4 vents; 3 in the warmer south side and 1 on the north side. The house is 1 1/4 storey; part of the wall in the 2nd floor is the ceiling. That part is about 5' with a 12/12 pitch until it meets the ceiling.

After having a bathroom renovated; the contractor used pink 2x4 insulation in the 2x4 walls and part ceiling/wall. I do not believe he used baffles for venting as he never deepened the 2x4 wall to allow for the baffle/insulation

I have recently demo'd and insulated a small hobby room with that approach for the ceiling (no baffle)

I have started to demo my bedroom and it was pointed out that I should install a baffle; I am in the process of doing that. In hobby room case I deepened the wall to 2x6 to allow for 2x6 insulation. In this case I'll have to deepen the ceiling to allow for the baffle and 2x4 insulation.

My question is; do I have to revisit my old project and install baffles in the hobby room? In an old house with little to no soffit ventilation. Are there any options I can look at before I tear again into my hobby room wall/ceiling to install baffles? If I don't do this am I kicking the crap out of my roof since the roxul is touching the roof?

Is there something about ventilation and old houses that I am not clear on?

 

Baffles are only used in roofs. Baffles are only used when there is air movement between soffit vents and the attic vents. So, if you have a roof area that's not ventilated or if you don't have soffit vents then you don't need baffles.

 

But you also don't want the fiberglass insulation in contact with a cold roof. Sorry, just jumping in.

Bud