im making a green house and have a base that is 144 inches across and i want to make a simple truss to span across.im using two 2x4x8 and want to simply cut two ends at an angle to make a a pitch roof. just wondering if there is a formula to figure out the degrees to cut each end so they meet up flush and i can set it down on the base i have built. thanks.
2007-02-16 10:41:28 · 9 answers · asked by purplethrob 2 in Science & Mathematics ➔ Engineering
The formula is arcsin(base / truss length).
In this case, the base is actually half of your 144" baseboard (with the other half being the base of the other side of the truss). So dividing 72 / 96 = .75, and taking arcsin(.75) = 48.6 degrees. That's half the angle of the ridgeline, with the other 8-footer making the other half.
The angle at the base of the 8-footer will be the complement, 90 - 48.6 = 41.4 degrees.
2007-02-16 11:07:15 · answer #1 · answered by Keith P 7 · 0⤊ 0⤋
You didn't provide enough information but here's how its done.
First the boards you are cutting are called rafters. You need a framing square. And you need to decide what pitch to make the roof a 4:12 pitch is fairly common. 4 being the height and 12 being the run. Place the square on the 2x4 and adjust its position so that one edge of the 2 x 4 intersects the square at the 4" mark on one side and the 12" mark on the other side.
The side of the square parallel with the 4" mark is the angle of the cut in the center of your building. The side parrallel with the 12" mark is the angle which will match up with your horizontal base. Since the span is 12 ft you need 6 runs to the center. So if you step off the square, repeat the above, you can determine the length of the piece and the location and angle of the cut at the peak and at the base.
2007-02-16 14:52:19 · answer #2 · answered by Roadkill 6 · 0⤊ 0⤋
This Site Might Help You.
RE:
how to calculate the angle to cut two 2x4x8 boards to meet flush at the top and span over144 inches .?
im making a green house and have a base that is 144 inches across and i want to make a simple truss to span across.im using two 2x4x8 and want to simply cut two ends at an angle to make a a pitch roof. just wondering if there is a formula to figure out the degrees to cut each end so they meet up...
2015-08-06 23:01:59 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Draw a right traingle, where the base is 1/2 the total span, or 72". You also know the length of the hypoteneuse (the angled truss piece), which is 8' (96"). Now, we know that cos(angle) = adjacent/hypoteneuse, then we take our calculator and punch in cos^-1(72/96) and get the answer of 41.4 degrees. On your drawing this is the angle between the horizontal span line and the angled truss length. We also know that the all angles in this triangle add up to 180 degrees. Thus, we subtract the two angles we know: 180-90-41.4 and we get 48.6 degrees, which is the angle the truss makes with the vertical in your triangle, and the angle you should cut the boards where they meet at the peak of the truss. Peace.
2007-02-16 11:00:01 · answer #4 · answered by aaron p 2 · 1⤊ 0⤋
Truss Angle Calculator
2016-11-11 04:30:57 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Yeah, pretty much the same place that most guys would take an extra three inches. But then again, I am pretty short. I might get more action if I added three inches to my overall height. Unless I take the three inches downstairs, but then walk around without pants or underwear. Of course if I do that, I'll probably end up in prison, and I really don't want that kind of action. So, I'll just be three inches taller, please.
2016-03-16 22:31:31 · answer #6 · answered by Anonymous · 0⤊ 0⤋
A construction man named Jeff could tell you the angle. His 360 is jeffhconstruction.
2007-02-16 10:45:18 · answer #7 · answered by Anonymous · 0⤊ 0⤋
it will be about 48.6 degrees on top and about 41.4 degrees at the base
2007-02-16 10:48:14 · answer #8 · answered by bluedude65 2 · 0⤊ 0⤋
draw it on paper
simple geometry
2007-02-16 10:44:48 · answer #9 · answered by agropelter 3 · 0⤊ 0⤋