Framing and Sub-Flooring - need to change the rafters, need span info.
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mjjstang
08-20-09, 01:26 AM
I have seen a chart or two which may be giving me the right info, but some charts show different snow loads etc, basically we have a one sided roof that butts up to an exterior wall, upon inspection it looks like the house had been changed a bit so they just cut the rafters and raised the roof. I have a pic
http://i5.photobucket.com/albums/y186/mjjstang/shepwalls.jpg
So the red line shows the verticle wall that I believe any way was not original and owners wanted more space. The blue is showing what I believe to be how the old roof went, because like I said, if you go into the attic space there beyond that exterior vertical wall, you can see that were the OSB and rafters come to the wall, they were sawzalled off. The roof is bowing, shingles very bad, its original where all the other roofing is new and shingles are good.
We already know we have to replace the roof down to the beams. So if we are that far, we were thinking with the right size framing, we could make a single span and remove the truss configuration. This would allow us to open up the bedrooms below or better yet we might want to expand the upstairs bedroom and just put in a kneewall towards the edge.
Basically I am wondering what we kind of framing members we need. Of course this is all based on the pitch, and spacing, as well as size of members used. And even then apparently you have to figure for snow loads based on geographics? Mid Michigan. I was thinking 2x8 This would allow for regular sized can lights among other benefits. It would however take away some space from the upstairs bedroom if we decided to give the space to it. but I assume there has got to be a good chart that would say what size we have to use. Thanks for the help!
http://i5.photobucket.com/albums/y186/mjjstang/shepwalls.jpg
So the red line shows the verticle wall that I believe any way was not original and owners wanted more space. The blue is showing what I believe to be how the old roof went, because like I said, if you go into the attic space there beyond that exterior vertical wall, you can see that were the OSB and rafters come to the wall, they were sawzalled off. The roof is bowing, shingles very bad, its original where all the other roofing is new and shingles are good.
We already know we have to replace the roof down to the beams. So if we are that far, we were thinking with the right size framing, we could make a single span and remove the truss configuration. This would allow us to open up the bedrooms below or better yet we might want to expand the upstairs bedroom and just put in a kneewall towards the edge.
Basically I am wondering what we kind of framing members we need. Of course this is all based on the pitch, and spacing, as well as size of members used. And even then apparently you have to figure for snow loads based on geographics? Mid Michigan. I was thinking 2x8 This would allow for regular sized can lights among other benefits. It would however take away some space from the upstairs bedroom if we decided to give the space to it. but I assume there has got to be a good chart that would say what size we have to use. Thanks for the help!
GBR in WA
08-20-09, 02:31 PM
There is no simple solution to your problems. The roof is sagging due to the previous remuddle. I would hire a Structural Engineer to evaluate the house.
The rafter size would depend on the span, species of wood used, required depth of insulation from your local Building Department. The wall between roof elevations needs is own attention. Roof shear flow, loads, wind shear, and structural integrity of the building are all at play here.
Be safe, G
The rafter size would depend on the span, species of wood used, required depth of insulation from your local Building Department. The wall between roof elevations needs is own attention. Roof shear flow, loads, wind shear, and structural integrity of the building are all at play here.
Be safe, G