I live in northern California where the summers are hot, but the winters are relatively mild — a few weeks of cold temperature (upper 20’s) but snow is rare to none.
I am building an 8×12 outbuilding with a 8/12 gable roof with an LVL ridge beam and 2×6 rafter every 16″. The rafter tails are exposed no soffit) and the intent is to have a cathedral ceiling.
The building is framed and the sheathing is on the walls but not the roof. I am going to insulate the building as a way to address heat build up inside the structure.
It is not clear to me if ventilating the roof will help keep the heat load down. The ventilation would be using a ridge vent in combination with some type of screening in the frieze blocks (yet to be installed). Will this ventilation help with the heat load or am I better off just packing the roof with as much insulation as possible?
With 2×6 rafters, there isn’t a lot of room for much more than R13. Furring on top of the rafters might give me some room for R19, but are there other ways to minimize heat gain from the roof given the 2×6 rafters?
Thanks,
JR
Replies
Probably lots of points of view on this topic. I'd vent w/ 1-2" of space above the insulation w/ the vent strategy you indicate. This may be as much to preserve roofing as it is control heat inside ... I'm not sure about this aspect.
I'd consider furring the inside of the rafters as much as possible to increase insulation thickness. It would be easy to e.g. do 2x2 furring and then an R-19 or R-21. Inexpensive, too. Furring the top side would involve details .... exterior roof, eave, end walls, etc.
I'd go 24"oc, not 16, maybe ... for such a small building, 16" is way overkill, It seems. Take the savings, by 2x2s and furr the ceiling down 1 1/2".
Just thoughts.