[quote=vince2][quote=Mark P]... I basically built the rafters standing in the attic and tore everything apart as i moved through the room. When all said and done the only waste was the sheetrock that had been there. Well..... the structual engineer stamp cost $600 which was funny because I drew the prints and he just stamped them, I guess he did model all the stresses on a computer which probably took him 30 minutes....
I'm a little surprised as the structure seems more complicated than simply adding collar ties and cutting the existing joists. Can you explain the ceiling construction a little more for those of us contemplating similar modifications?
What I did consisted of not wanting to waste an inch of materials if necessary so heres how I did it step by step.
I had exsisting 2x8 rafters and 2x10 joists which supported the original sheetrock ceiling , there was 5/8 plywood on top of the joists making a floor in the attic.
first thing I did was roto-zip all the sheetrock around the outside of the room then I pulled all the plywood up leaving several peices up there as a working platform that I could easily slide around.
Then I kicked down the sheetrock from above and it would come down in huge peices so this went fast ( as in less than an hour and it was out the windows in a dump trailer with the help of the wife.
I also threw down all the plywood but 4 peices as working platform
I counted my rafters which was 26 so I bought fifty two 16' 2x4s ( these turn the 2x8 rafters into 2x12 rafters when added to the bottom of rafter and nailing the plywood to the side splicing them together
( I used the plywood I removed from the flooring and cut it 12"s wide but since it was only 8' long I had to have a splice half way up the rafter, when this happens you must add a 4' long piece to the other side of the splice centered on where the plywood meets for reinforcement)
The top of the 2x4 is cut on a 45 degree angle and fits tight against the ridge and the bottom of the 2x4 is cut with what I call a " birds-mouth" which fits neatly on the top of the "wall"
When nailing I used a nail gun and 8d nails and loaded the plywood with nails on 6" centers being careful on the 2x4s as to not split them since they as so skinny.
My collar ties were the Old joists I would remove after every 3 rafters I built , I initially bought two 12' long 2x10s to get started, knowing where to cut joist was achieved by measuring out 18" from the wall at the front and back of room and snapping a chalk line, this works good with locating collar tie placement as well
Considering the amount of roof systems I have built I knew this would be a stout remodel of the roof, I still needed a structual engineers stamped approval after he was done doing all the wind/snow load modeling just to be all legal and so on.
Im sure I probably forgot something, just ask if I did!
I almost forgot, dont forget the Hurricane straps , Simpson Strong-Ties cant recall actual model number but they are long rectangular steel that tie the rafter to the top of the wall , you may want to buy or rent a palm nailer when puting these on since these alot of nails