Are there any good books or other sources on cutting valley rafters when the pitches are equal, the runs are not equal and the ridge height is not equal. The runs are 10’11.125″ (22 wide with 1.75 LVL ridge) and 11′ 11.125″ (24′ wide with 1.75 LVL ridge) with a 9/12 pitch on both sections that intersects. The overhang is 12″. The Architect calls out for 1.75″ by 9.25″ LVLs for ridge and valleys.
I understand that I am dealing with “crossing a rectangle” not a square. And there will be unequal cuts at the ridge and plate.
I have never done two different widths.
I appreciate any advice. Thanks
Replies
Check out Roof Framer's Bible by Barry D. Mussell. It's about $20 and I think addresses your question. Another book I've seen recommend, but don't own myself is called "A roof Cutters Secrets"
To tell you the truth though, The roof does not sound that complex, but I'm no framer. I'm sure Joe C. can answer your question without you having to go buy a book.
Thanks and who is Joe C.?
He is one of the regulars here. Didn't know how to spell his last name. I think he goes by the login name of "framer". If I remember correctly he knows a *lot* about roof framing. Like I said though - your situation, if I understand it correctly, shouldn't be that difficult. Matt
Roof framer's bible will give you tables upon tables of complicated rafter cuts. But Will Holliday's (sp?) "Roof Cutter's Secrets" will talk you through it step by step. It also has the an index in the back that will take you through the corresponding keystrokes on a Construction Master calculator for several complicated roof examples. Both are great books and both should be onhand should you be seeing more of these roofs in the future. Money well spent. Both of them sit in the door pockets of my truck.
a lotta good them books do ya sittin in the truck!...lol
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
Sorry BHACKFORD but I drew this using 1-1/2" ridge and valleys but hopefully you'll get the idea.
I don't know what way you figure rafters but with a 9/12 pitch and your 24' span with deducting 1/2 the thickness of the ridge your run would be 11'11-1/4" giving you a Supporting Valley Length of 19'1-5/16".
Now your Supported Valley the easiest way to figure it is to go with the 22' span/2 = 11' Run with no 1/2 thickness of ridge deduction and deduct 1/2 the thickness of the Supporting Valley rafter.
That would give you a Valley length of 17'7-5/16". That would be the center point as if there was no Supporting Valley but if you look at the drawing in plan view you will see that you would have to deduct 1/2 the thickness of the Supporting Valley which would be 3/4" in plan view.
So if you would mark your 17'7-5/16" Valley Length and then mark a 9/17 plumbcut just measure back 3/4" plumb and that will give you your correct Valley Length of 17'6-7/16".
If you look at the drawing you will see that the valley creates a Triangle with a 11' run and 11' rise giving you a Hypotenuse of 15'6-11/16" deducting 3/4" for 1/2 the thickness of the Supporting Valley giving you a valley run of 15'5-15/16" for a 9/12 pitch the valley with that run would be 17'6-7/16"
Supported Valley length is:
22/2 = 11' run
Valley Length 17'7-5'16"
17'7-5/16" - 3/4" (Plumb) = 17'6-7/16"
Joe Carola
Thank you...thank you...thank you.
I understand the process where you remove the ridge to calculate the center point. What are your thoughts about the method shown in FHB # 130 page 67? What about a "California valley"? Where I could frame on top the roof, like I have done many remodels?
How do I come up with the angles at the ridge. I just bought a Construction Master Pro. Hopefully, this will help. This is for a possible up coming job.
To make it worse, there is a dormer in the front too...so two more valley rafters. That on is 16' wide 12/12 intersecting the 24' wide 9/12.
I am sure I will figure it out once I get up to speed with the CMP. The easier way to go is truss the roof, but I figure I better break down and learn the right way.
Edited 10/4/2004 10:04 pm ET by BHACKFORD