OT: Roof framing, alteration Options

[thomasotten]

I have an existing roof on my house that is pitched and creates a cathedral type ceiling underneath. I am considering increasing the pitch of this roof, for ascthetic reasons mostly, but also to add insulation to the roof, which I don't thick is adequetly insulated. There is no attic space right now, so I cant' be sure of the insulation, although it gets hot in summer time. I want the final roof to be 12/12, and to do this, I would need to raise the ridge by about 2'. From the ridge, I would then run rafters down to the bottom of the roof fascia. Instead of raising each rafter up and causing a mess, I am considering building a structure over the exsiting roof, and then sheathing over. That way I don't disturb the ceiling. I was thinking of also doing this in phases, keeping the existing shingles on as a I go. What do you think?

[rhodyguy]

existing roof (3 tab, etc) tear off is an equal weight trade when replaced with a like product. look into poly-iso panels. light weight, high r value. they fasten w/long screws then resheath. spread out over the entire roof, the sheathing shouldn't add a high load. prob less than a reshingle over an exsiting roof. see if continous ridge venting will provide the air flow you need. you have to make an ajustment at the facia boards due to the added thickness.