Is the saw blade set to 45 degrees for side-cuts on all regular valleys and hips? Some instructions seem to say this, but others seem to indicate the side-cut is a variable.
If the rafter tables from the framing-square is used it would vary according to pitch, and not always be 45 degrees. Or, it may be that 45 degrees is “close enough”. I am a little confused and any clarification would be appreciated.
Replies
I can't imagine why anyone would think it's always 45°. (Although it is 45° on 12/12 roofs)
It would be based on the pitch of roof that the valley rafters sit on.
The dead fish goes with the flow.
Thanks for the reply Boss. I probably didn't ask the question right, and I still may be confused. I am not talking about the plumb-cut but the side-cut. Since the angle in plan is always 45 on a regular hip and valley wouldn't the side-cut match this?
As mentioned, some information I've read indicates this others say it varies. Or that's the way I've interpreted it.
I think if you're not confused, you just don't uinderstand the situation...........(-:
Maybe it would help to break it down into steps. Let's take an example of cutting a valley rafter where the pitch of the main roof (Where the valley is sitting on) is 6/12, and the roof tying into it (The pitch of the valley rafters) is 9/12.
First I'd make the plumb cut on the valley rafter. I'd lay it out using a speed square (or framing square for you die-hards) and set the pitch at 9/12.
Then I'd make the flush cut - Where the valley rafter lands on the roof below. I'd lay out the cut at the inverse of the 9/12 pitch, since this is a horizontal cut.
Looking up the 6/12 pitch on the speed square, I'd see that the 6/12 pitch is about 27°. I'd lean the blade on the saw so the cut was 27° off plumb. Then I'd make the cut. (The bevel angle comes from the roof the valley rafter lands on - Not the pitch you cut the angle at)
Then I'd test fit the rafter and realize I cut it backwards. Hopefully you can eliminate that step...................(-:Periods of tranquility are seldom prolific of creative achievement. Mankind has to be stirred up.
OK, I think I am beginning to understand. I have been describing a situation that applies to an equal-pitch and equal-span. The run of the hip/valley is the diagonal distance of a square made by the run of the commons. I refer to this as a "regular" roof. I am trying to get a good understanding of this before moving on to an "irregular" roof.
So, with a regular roof, where the hip and valley will always intersect the ridge at 45 in plan, will the blade be set at 45 for the side-cut? The way I visualize it, it would. But I am still uncertain because some information I read indicates something other than 45 may be required.
I have framed a coupel of small gable roofs and have a fairly good understanding of them. I don't yet have any experience with framing hips and valleys.
Thanks for your patience.
Unless the main roof is at 12/12, nothing will be beveled at 45°.
I don't really know how else to explain it. Maybe someone else will jump in that can do better.
Visiting joefuscoe.com might work - He has a ton of stuff at his site.
Or try building a mock-up of one with some scraps of lumber and plywood. That should give you a feel for how to do it.All the money, background, prestige... none of it compares with hard work and clean living. [Ari Rapkin]
Boss,
I'm not sure I understand what you mean that nothing will be beveled 45 but a 12-12 roof. On all regular roofs, the bevel or saw tilt is 45° because the hip/valley in plan is 45°. The side cut is on the square so if you had to cut the rafter by hand you could put the right bevel that corresponds to the plumbcut.
I'm probably not understanding what you meant. I'm like that you know, just ask anyone ;-)
Boss,
After rereading your posts, I believe you are referring to a blind valley (aka scotch valley, overframed valley, california valley) Then the bevel on the jacks is the same as the angle of the roof they are landing on. Just get the number off the speed square and tilt your saw cut them. The seat cut on these jacks (assuming a regular roof ) is 90-the speed square angle. You can use a framing square, which lays out the seat cut more accurately. If the pitch was 6-12, 6 on the tongue and 12 on the blade and mark the blade.
I know you already know that, I just wrote it for the benefit of the author of this thread.
Here's a pic of a california valley. The pitch was 6-12 for both roofs. The level cut is made as described above and the saw tilt was 27° We beveled the sleeper board too to prove a point. Bygones.
View Image
Edited 4/29/2003 7:22:05 PM ET by TIMUHLER
I think that your thinking trusses and he is thinking conventional framing where you usually use a "live" valley.
When you use trusses if you are doing a valley then 99 percent of the time they will be lay-overs and unless the roof is a 12:12 then nonething will be cut 45 deg.
If you are cutting jack rafters to the valley on a regular equal pitched hip roof then the saw will be tilted to 45 deg. always.
It is when you get to off-pitch roofs that all hell breaks loose.
You're 100% right - I was thinking of an over-framed valley.
When you deal with trusses half your waking hours for several years, you tend to think that way first.........(-:You know you're getting old when you stoop to tie your shoes and wonder what else you can do while you're down there.
By the way, I was talking about Jacks, but the prinicples apply to hips/valleys.
For all regular hips/valleys, the saw tilt should be set to 45°. Because the hip/valley bisects at 45° in plan, you should set your saw tilt to that angle.
The side cut does change depending on the pitch. For example, draw a 12-12 plumb cut on a 2x6 and draw a 2-12 on a 2x6. Set your saw to 45 and make both cuts. When you measure the resulting bevel on each peice of lumber you will have cuts steeper than 45. This is because the saw is entering the lumber at different angles. A 0-12 or square cut is the only time you would have a 45° bevel on the lumber after you cut it.
Does this make sense? The angle that results from setting your saw to 45° and cutting a 45° (12-12) face or plumb cut is the same angle as the plywood will make when it is laying on the roof at a hip or valley. You can use the sidecut number on your rafter square and multiply it by 4 and that is the distance you should pull your tape across the top (or bottom if it's a hip) on the plywood. Then snap a line from that mark to 0 on the same side you measured from and that is your pattern for cutting plywood at hips/valleys and it is the angle across the top of your jacks.
One thing to be careful though, is that your speedsquare and saw both tilt from 90. So if you had a bastard hip/valley that bisected the plan 50° in plan, you would have to tilt your saw to 40° to get the right angle.
There are a lot of guys here who can explain this all better than me. Hopefully this points you in the right direction.
For more info go to http://www.josephfusco.com. Joe has some great drawings showing how all this works.
Thanks TIMUHLER, your reply was very helpful. I will also visit the site you recommended. I am starting to understand; I just need to put it to practice.
Rlb1950,
I highly recommend buying the membership to JLC's website. You'll get all of their articles going back to 1986 on CD and access to their library on their website. http://www.jlconline.com I've been buying that for the last few years and the wealth of information that is available is amazing. The articles on roof framing are very well written and will answer most of your questions.
Hope that helps. Any other questions you have, post them at Joe Fusco's forum website. There are a number of roof framers that frequent that forum. http://www.josephfusco.org/phpbb/index.php