Want to begin finishing attic, but have questions (pics included!)

[originalbatman]

I've been reading and searching these forums for several months now, as I am getting ready to start down the path of refinishing my attic. I live in a 1989 2 story brick house with an attic that I believe was built to be finished. It has a staircase to it, as well as skylights in the attic, that to me, indicates that the attic was meant to be finished. That's apparently what the first owners wanted to do, but never did. The second owners didnt really think about doing that, but when they put the house for sale, they did mention that you could finish it for living space. I'm the third owner.

Basic construction facts :
floor joists are 2x8 16" OC except where they look to span about 18 feet (over hallway on second floor) where there are 2 of them 1 1/2 inches apart. The hall is 3 feet wide. Other longest span is in master bedroom where it is 14 feet 2 inches but looks to be just 2x8 16" OC. Most spans are just 12 feet. The species of wood is either pine or douglas fir, but i wouldnt be able to tell you which. The attic subfloor is already down - 3/4 inch 4 x 8 plywood. Roof rafters are 2x6 16" OC. It is a hip roof (slanted on all 4 sides) with 64 inch ridge vent area (ridge vent slightly smaller)

For insulation, I plan on placing 2x4's perpendicular to roof rafters, and then on top of those 2x4's, running parallel to rafters, more 2x4's (on end) to build up enough space for R30 insulation.

My biggest concern is the ventilation of the roof, specifically the 2 ends of the roof where the rafters just dead end onto the hip rafters so even with those styrofoam spacers between insulation and roof, there would not be any circulation to ridge vent.

Any ideas, help, suggestions would be appreciated.

As an added bonus, see my earthlink homepage, with pictures! and descriptions.

home.earthlink.net/~mis4marty


thanks in advance

batman.

[markiz37]

I'm not a pro, nor have I ever done anything like this, but here's my take on this. Even now, with the wide open attic, the ventilation in those cripple rafter spaces is somewhat constricted due to the hip rafter that is in the way. The air that comes up from the soffits just does not have a straight path to the ridge vent, that's just the way it is with hip roofs. So I would't worry about it too much, unless you are already having problems with inadequate air flow. As long as you leave a gap between the roof decking and the insulation and line it up with raft-r-mates, and leave a gap under the hip rafters, some fresh air will find its way up there to exit via the ridge vent. The only othe option I see is closing off the ridge vent and putting an electric fan in to suck the air up and out, but I would finish it first and see if I had any problems and only then use it as a last resort. Good luck to you.

[Caoimhin]

I know as much about renovating attics as I do birthin' babies, but here's my two cents.

To really get the flow from the soffits to the ridge, it would seem as though you'd have to make almost a suspended ceiling -- four well-insulated roofs that look like what you currently have, but on a plane (for each) that starts at the same eave as the current, then drops a few degrees at the top. This would leave a small space at the eaves (between the current roof and your new room's ceiling), and a greater space at the top. Insulate the jebsus out of your new ceiling, and leave the current space alone.

To make it, you could hang vertical members from the current rafters, with a box at the apex of it all, parallel to the plane of the surface of the planet.

This is pretty drastic, but it's always easy to make plans with other people's time and money!

Good luck!