Insulation in bonus room

[dhumac]

Picture First!

This is a picture of my office above my garage. I'm currently insulating it and as you can see from the picture, I have an attic vent running along the underside of the roof on both sides from the soffit to just below the ridge vent.

Where the room's roof is sloped I have filled the area with insulation, 2x6 truss + I've sistered a 2x4 on to that so I'd have greater insulation at that point. The vertical wall will have a styrofoam backer and then fiberglass, and the horizontal roof is R40+. The soffit is blocked with styrofoam insulation and I've cut a small opening for the attic baffles and then spray foamed all around it so I'd get no further air (or in reality snow) coming through the soffit. In my area, I'm on a hill and get heavy wind off the water. I would get snow coming through the vented soffit.

My question is, as per the picture, do I need additional venting in that triangle non conditioned air space. It will be somewhat air tight, but the air baffles are joined by overlapping so there will be some small amount of air leakage. I don't want humidity problems / over heating / under cooling there, so I'm not sure if I should open maybe 3 of the 21 rafter bays so air can flow upwards to the ridge vent.

I don't have that concern on the opposite side, since it feeds into a workshop with no bonus room, and it can also vent that way.

If I'm not making sense - let me know, and I'll try to make it clearer.

Thanks for any guidance.

 

[Falcon67]

I would if the roof is pulling air from the eve to the ridge. That heat needs to go somewhere. I'd insulate the side walls and remove the insulation under the deck in that cavity. Or at least cut enough out at the top of the wall to let the heat into the rafter area to head for the ridge.

 

[thammel]

It appears that it should work. I have a similar situation but I insulated the kneewall and not the roof line in the triangular section on the right side of your picture. Are you intending to store anything in the right side? Why is it fully insulated>

Tom

 

[DC73]

The way you have it drawn, the triangular area is fully insulated. If you vent it, you have effectively created a room that can approach outdoor temperatures so you would then need to insulate the wall of the office.

Falcon67 has thrown out another option. Just insulate the office and leave the triangular area as a vented attic space.

Here's an article that might be of good use to you: http://www.greenbuildingadvisor.com/blogs/dept/musings/how-build-insulated-cathedral-ceiling

Personally, I would leave the triangular area insulated as you have shown, I would not ventilate that area but I would install doorways so as to be able to use it for insulated storage. If you go this route, pay close attention to the article I linked as you must get the details of a cathedral ceiling correct to avoid moisture problems.

Good luck,

DC