I am framing a second floor room that has sloped ceilings. I’ve done this a hundred times, building knee walls and installing collar ties is all pretty simple. This time I’ve run into something I’ve never had to do before. The roof is a 9/12 pitch. The knee walls were easy, I put about a 38 degree bevel on a 2×6 for the top plate and a 38 degree miter on the studs. The end wall is easy too, blocking between the rafters for the top plate to nail to and bevel the studs as they get longer and longer going up the roof. By end wall I don’t mean gable wall, this is an interior wall of the house.
The hard part is this, the knee wall and the end wall do not meet at a 90 degree angle. The corner of the room has about a five foot section of wall that is at a 45 degree angle. So, the knee wall runs strait, turns 45 degrees for 5 feet and then meets the end wall. The wall is finished on both sides so the top plate must be beveled on both sides and each stud must have a compound miter as it climbs up the roof to the end wall.
How do I calculate the angles and if the studs are spaced sixteen inches on center how much longer will one stud be from the next? Like I said it’s a 9/12 pitch roof. I hope you understand my discription.
Thanks!
Replies
This ain't a piano you're building.
But if you want it that way, Joe Carola, or Dieselpig can probably help you better. All I can say is how I do those.
chaulk the layout on the floor.
nail the bottom plate down there.
use the laser level or the plumb bob to mark same edges at the rafter plane on a couple rafters.
use a straightedge or chalk line to mark the rafter bottoms.
if you want to rip the top plate on a true bevel then run the straightedge verticle and tale off the angle with a bevel square. Transfer that to a scrap and measure with the speed square to find the setting on the rip t5hat will also play into your bevel on the studs.
Then do the 16" oc layout on the bottom plate.
use the laser or the plumb bob to locate same on the top plate for each stud. Measure length in place, cut on chop box and nail in.
sounds slow, but done almost as fast as scratching your head to figure out what I just said.
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Good old school answer Pif, except for the laser level thing.
Wood Eye!
We just use the Hairy Eyeball, still works for Us!
Yeah, another easieer way for such a short wall is to just platform frame itshort and whack off a couple of shims for nailing the top in place.
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I forget where my plumb bobs are, it's been so long since I've used them!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I forget where my plumb bobs are, it's been so long since I've used them!
At least you remember you have some.
CRS is creeping in tho, LOL. But I can still remember sex! It was something we talked about in high school, wasn't it?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
But I can still remember sex! It was something we talked about in high school, wasn't it?
Yea, back when they called you Pimpin. I believe your next transitional name will be Puffin, as in huffin and puffin.
If you are like me, I am ready for that transitional name now......too much office work and chocolate chip cookies.
huffno fair, you must have heard me breathing hard yesterday.
Clearing a lot for new addition with one helper. That chainsaw got heavy by end of day. I'm out of shape from being sick so much this past year.
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My advise is to use my system: I start off slow and taper off as the day goes on.
Thanks piffin, I'll use my bevel gauge.
This ain't a piano you're building.
Great line. LOL
common line heard around here. I can't take credit for that one.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Yes, around here we also talk about "not building a church". No disrespect intended.
Also if 45 degrees, hip and valley framing angles should work.
Common quality compromising phrase around here...."You can't see it from the road." or "You can't see it from my house." I would think these lines are about as common as the universal term "fart fan".
Already posted this over at the JLC Forums, but what the heck, it won't hurt to post here as well. This example is a “prow peak” with an irregular Plan angle, dimensions in decimal inches. It doesn’t matter if we look at this as a wall, half of a Hip-Valley rafter or prow peak; the solutions are all the same. And don’t be intimidated by all the cyphering. The calculations need not be this involved. I’ve gone into this in detail and people can pick and choose which method they like the best.Initial Values:Main Slope = 10/12Common Rafter Run = 186.625Ridge Length = 48Proportion and the Pythagorean Theorem return:Common Rafter Rise = Prow Peak Rise = 186.625 × 10/12 = 155.52083Common Rafter Length = Square Root ( 186.625 ² + 155.52083 ² ) = 242.93131Prow Peak Run = Square Root ( 48 ² + 186.625 ² ) = 192.69896Prow Peak Length = Square Root ( 192.69896 ² + 155.52083 ² ) = 247.62799The angles may be solved using trigonometric formulas or the dimensions substituted in the equations given in the diagrams in this Prow Peak link.Common Rafter Pitch Angle = arctan (10/12) = 39.80557°Plan Angle (measured between the Ridge and Prow Run) = arctan (186.625/48) = 75.57614°Prow Pitch Angle = Valley Rafter Pitch Angle = arctan (10 × sin 75.57614°/12)= arctan (155.52083/192.69896) = 38.90583°Backing Angle = arctan (sin 38.90583°/tan 75.57614°)= arctan ((155.52083 × 48)/(247.62799 × 186.625)) = 9.17588°Jack Rafter Side Cut Angle = arctan (cos 39.80557°/tan 75.57614°)= arctan (48/242.93131) = 11.17692°Sheathing Angle = arctan (tan 75.57614°/cos 39.80557°)= arctan (242.93131/48) = 90° – 11.17692° = 78.82308°Framing a wall the difference in stud length would change by:Spacing O.C. × tan 38.90583° = Spacing O.C. × 155.52083/192.69896 = Spacing O.C. × .80707Backing Bevel = 9.17588°For the prow peak roof I needed the miter and bevel angles to cut the purlins in order that the fascia would follow a plumb plane:Angle on the Stick = Sheathing Angle = 78.82308°Saw Blade Bevel = Backing Angle = 9.17588°Difference in Length between Purlins on 48 centers = 48 × tan 11.17692° = 9.48416
Joe Bartok
Edited 10/17/2006 12:07 pm ET by JoeBartok
Moncia, yes, theres value in figuring out how to do this from the technical point of view, but if you just want to get done fast, you're going to have to learn how to eyeball things.
For starters, I grab a one foot chunk of material and make my first attempt at cutting the top plate connection perfectly by eye. I'm usually wrong...sometimes close, sometimes very close and sometimes ridiculously wrong. By my third attempt, the cut will fit...guaranteed. I then use this one foot piece as an idiot stick. I can quickly pull the numbers off it for both bevel and angle, if I feel the need to mark things exact before I cut, but in most cases I'm probably gonna just continue eyeballing every cut because once I get the "feel" it's gonna be fine for a rough frame.
Once you have the top plate fastened, the studs are easy and I do them the same.
A five foot section involves about four studs....about four minutes worth.
Like I said, sometimes it's important to technically sit down and figure this stuff out but I haven't had the hankering since I was in my early thirties.
blue
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if it is a 45 degree angle, i start with hip angles 9 hip on speed square or 9/17 on framing square. you may need to adjust a degree + or - for crowns in floors or roof. and still measure each stud for same reason.