Iím framing 17x10 room addition to the side of the house I want to do cathedral ceiling. So far I got plans for triple 2x12 ridge beam supported on house end by three 2x4 in the existing outside wall and three 2x6 on the other end, where wall is 6 inch. Rafters to be 2x10 that should give just enough room for R30 insulation and little space for ventilation. The plans I have are not for exactly the same size addition so Iím wondering is I could go with less lumber for the posts and the ridge beam think double not triple. And second question because existing house use trusses for roof they are made out of 2x4 to match the roof pitch and height in the addition with 2x10s is that mean that I have to have the double plate lower than the existing house so that the birth mouth does not eat half on that 2x10
That would depend on the 'heel height' of the truss you are matching up to.
If it is tall enough off the plate, you will be fine.
No idea what our code would say about the double/triple ridge beam. Your location isn't shown.
What is your snow/wind load?
Also, r30 insulation is 9 1/2" thick, so your rafters will be full of insulation. There will be no room for an air space, which is critical to the roof being ventilated properly. You might want to consider a closed cell spray insulation.
Originally Posted by Bud Cline
Go ahead and apply for a variance, those guys at City Hall can use a good laugh.