NEW ROOF FRAME OVER OLD ROOF

[Eric S]

I HAVE AN OLD HOUSE THAT HAS A POST AND BEAM FRAME. THE ROOF RAFTERS ARE 3ft OC, RADOM SIZED AVERAGING 4x4 AT TOP, 5x5 AT BOTTOM. THERE IS NO EAVE OVERHANG(UGLY) AND ICE DAMMING IS A PROBLEM SINCE THERE IS NO VENTILATION. MY IDEA IS TO REMOVE OLD ROOFING (WOOD,METAL,ASPHALT) AND ADD NEW 2x6 RAFTERS 2ftOC ON TOP OF OLD DECKING WITH COLLER TIES THROUGH ATTIC SPACE, THEN ADD PLYWOOD AND NEW ROOFING.
THIS WILL GIVE GOOD VENTILATION AND IMPROVE LOOKS WITH OVERHUNG EAVES WITHOUT DISTURBING THE INSIDE WALLS/CEILINGS OF THE HOUSE.

ANY ADVICE/COMMENTS WOULD BE APRECIATED.

[mjpliv]

If you are attaching the new "rafters" to the existing roof and the existing roof is sound then I see no reason for the collar ties. The new 2x6 "rafter" are basically just spacers unless I am missing something.

[Rich]

The only thing I can see (and it might not be an issue) is possibly framing between the existing rafters to bear the new rafters. The only reason I mention it is that many times they'll only run the plywood up... just make sure there is something that the new rafters are bearing on.

[Eric S]

SINCE THE OLD ROOF HAS SMALLER SIZE RAFTERS AND ARE ONLY
3ft OC, I THOUGHT IT WOULD BE BETTER NOT TO USE THE OLD ROOF TO SUPPORT THE NEW ROOF. USING COLLER TIES WOULD KEEP THE NEW ROOF INDEPENDANT OF THE OLD ROOF. ALSO THE OLD ROOF SAGS A BIT ALONG THE RIDGE, SO I COULD ALSO STRAIGHTEN THINGS OUT RATHER THAN FOLLOWING THE SHAPE OF THE OLD ROOF.

THANKS,
ERIC.

[grumpydasmurf]

I just put in a bid for framing somethign similiar. The roof is cirrently a 3/12 with no ventilation. We are going to frame it to be 5/12.

We are going to leave the existing 2"x4" rafters in place only removing the sheating. We will then frame up the roof sistering our new rafters against the sides of the existing rafters.

The architect wanted us to place the rafters ontop of the existing but I had to show to him that the new rafters needed to rest on the wall for support.