I have been scratching my head over this one for the last two days. Any help would be greatly appreciated. I am building an addition to my house. The house and the addition will have a 5 in 12 pitch gable roof. The two ridge boards run perpendicular to each other. Since this is an add-on to the original house I do not have a true valley rafter but instead plan on nailing a 16″ wide strip of 5/8 ply directly on top of the shingles where the valley will be after the new addition is completed. The purpose of the 5/8 plwood is to reinforce the existing roof where I will be nailing the valley ends of my valley jacks for my new roof. I am desperate for a logical and simple way to calculate the compound angle for the valley jacks! My current method of “eyeballing” that cut leaves alot to be desired in the efficiency department. Thanks in advance for any help that might be forthcoming.
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The level cut is the compliment of the pitch of the addition roof
In your case 5/12= 22-1/2deg =>67-1/2 degrees
the bevel would be the slope of the existing roof
Flop the saw over to 22-1/2 deg
(Aside... How come there isn't a degree key on a key board???)
I would reccomend cutting back your existing shingles and nailing down a 2x something valley board.
put some ice & water shield in the valley and do a single cut valley w/ your shingles.
Run the addition shingles onto the house and cut the one you replace on the house.
Mr T
Do not try this at home!
I am a trained professional!
"How come there isn't a degree key on a key board?"
You can find charachters like that in the "character map" program. Try hitting your start button, then programs, accessories, and system tools. You should find "character map" under that. It has all sorts of wierd characters you can stick in text:
Degrees º
Registered trademark ¯
Copyright ©
And other things known only to God: ÅÍÔÚåù
I worked myself up from nothing to a state of extreme poverty.
That's assuming Mr. T is running Windows, statistically a pretty good bet, but not always true.
Hey now - Don't go tryin' to confuse me with facts again.
Us conservatives don't like that, ya know................(-:
Look, if you don't like my parties, you can leave in a huff. If that's too soon, leave in a minute and a huff. If you can't find that, you can leave in a taxi.
(Aside... How come there isn't a degree key on a key board???)
º Unlike old fashioned typewriters, computer keyboards don't have enough keys for such luxuries as degreeº symbols. However, they do have an"Alt" key which should be handy at typing words like "Alter-ego" but it doesn't work that way. But if you hold down the Alt key and then press - on the numeric keypad - the magig numbers 167 you will get a degree symbol º.
Hope this helps. -Peter
Thanks for the response Mr. T. If I am using 2x6 rafters, I assume you mean that the level cut is the one that I would draw out on the 5.5 " side of the 2x6 and that I would set my circular saw to 22.5 degree and saw that line. If the above assumption is correct, I have two further questions. First, from which edge and which direction is the 67.5 degree measured from for the level cut and second, how do you determine what degree goes with what pitch. Also are you using the term slope and pitch interchangeably? Sorry to be so dense but I don't quite get it yet. Thanks again
67.5º from square. Put your speed square on the 5-1/2" side of the rafter.
Rotate it onthe pivot point until 67.5º lines up with the edge of the rafter.
Draw a line along the square.
set bevel on circular saw to 22.5º
saw so the line you drew will be the long point (down hill side) of the rafter.
See attachment
Keep your fingers away from spinning blade!
Good luck and don't forget the pine bough when your done!
Mr T
Do not try this at home!
I am a trained professional!
Mr. T., thanks a million for your second reply with the diagram. A picture is worth a thousand words.