6/12 roof pitch

[jmwhite]

I am trying to get an easy way to determine the run (length) of roof rafters for a 6/12 roof pitch.
I have standard 8' wall height. room deminsions are as follows: 16' x 14'
The roof will be a gable roof with the center beam running ascross the 16' width (8' from each end).
If I am correct, the rise on a 6/12 pitch with a 8' wall wuld be 4'. Does this sound correct?
How would I determine the length of the roof rafters?
Any information is greatly appreciated.

[jmwhite]

I am attaching a drawing for bettter understanding of what I am trying to do.
I need to know
1) Run of roof rafters
2) Would I need to use collar ties
3) The rise if I am using a 6/12 pitch
4) What recommended size ridge board/ beam to use and attachment method to house wall
5) What recommended size rafters to use
6) Any problems that are apparent with the drawing.
Please respond.
Thank You in advance

[Rich]

First off the rise/run and length of the rafters have nothing to do with the wall height. It has everything to do with span length and roof pitch.
the rise on a 6/12 pitch with a 8' wall wuld be 4' That statement is very incorrect.
Is what you would say is the rise on a 6/12 pitch with an 8' span would be 4'.
You can get exact measurements by using my Roof Calculator (http://www.construction-resource.com/roof-frame.php). Enter in the PLAN distance from outside edge of wall to centerline of ridge beam. Enter the pitch as a single number 6 - not 6/12. It'll do the rest.

[jmwhite]

Thanks For the Info. Very Helpful!
Do you have any recommendaions as to size rafters, size ridge board and weather I should use collar ties?

[grumpydasmurf]

Have an engineer draw you up something.

[doyle]

I can't make out the dimensions on your attachment, but assuming the ridge board is 16' long and the rafters will eash be in the 14' direction, then your rise will be 42" based on a 6/12 pitch (7x6=42).

If it were me (bullheaded) and it was an addition to my own house, I would use a 2x8 ridge board (7-1/4" wide) sitting on top of a 34-3/4" tall ridge beam support piece, which is sitting perfectly vertical on top of the top cap. There would also be a stud directly underneath for support. The rafters would be 2x6.

[mjpliv]

Are the exterior walls the only load bearing walls (those located above footings) or is there another under your propose ridge location?

[jmwhite]

The only load bearing walls are on the outside. No inside supporting walls on the 14X16 foot room.

[mjpliv]

Unless you use a full span, structural beam to carry roof loads at the ridge you will have to use ceiling joists or collar ties to restrain the walls from pushing out from roof loads. By using a center ridge BEAM all of the loads are then vertical.

[Joe Carola]

To get an exact Ridge Height you can do it two ways.

Get your exact run after deducting 1/2 the thickness of your ridge.

Run (To The Outside of the wall) x Pitch + H.A.P. cut (Height Above Plate) = Ridge Height

Run (To the inside of the wall) x Pitch = Plumbcut = Ridge Height.

This drawing I did was with a 5/12 Pitch and a 7" Run to the center of an 1-3/4" LVL Ridge. In this drawing I showed how to figure the Ridge Height from the inside of the wall deducting 7/8" which is 1/2 the thicknes of the 1-3/4" LVL ridge using a CMP Calculator.

Joe Carola