Building my first shed need help!

[newby]

I do have a little framing experience so i am not worried about that. But when it comes to the roof trusses i am lost. I don't know the lingo. If I could get some angles and number from you guys that would be great! I am building a 10' x 12' and i want a 7/12 pitch. What should i do? I have used the calculator on here but i dont understand the lingo once again.
How do i know what angle and where to cut the BMouth?

[woodall83]

First off, if you're using trusses you don't have to cut the birds mouth. The bottom chord of the truss sits directly on top of the top plate. Here is a site to help you determine rafter length:

http://www.wendrickstruss.com/Calculator/index.asp

[Richard A Hetzel]

Why would you need trusses to span ten or twelve feet?? That makes no sense.

[Don_P]

I think it just a terminology mix up and was assuming Newby wanted info on how to cut rafters. I'm working around the house today waiting on a call to go shoot some grades. I've about collected the toys and some scrap to lay one out and take some pics of how to hand frame it. If one of the roof pros wants to chime in please do though.

I did stop in last year at one of the neighbors where I was working, I saw things had ground to a halt on a little 12' wide shed. Rafter cutting was stumping him so I took measurements and cut him a pair of patterns that night. Took them out the next day, held them up to show how it worked and figured he was on his way again. About a week later I saw one of the local jacklegs rolling in with... tiny trusses. Shoot I would have been happy to overcharge and build him a set. Whatcha gonna do :D.

[woodall83]

Apparently not alot makes sense in your little world.

Trusses of that size are easy to build and easy to set and are comparable in price to doing rafters. You can use 2x4's in stead of 2x6/8's. You get more headroom if you use rafters, but it's all preference. There's nothing WRONG with building trusses that size.

Newby, first buy a rafter square, then google how to cut a rafter. It'll be alot easier than me explaining it here.

[Don_P]

It was not my intent to offend you Woodall. You are correct in that trusses can be used, and yes site built trusses would compare very well. Feel free to show how to build this as a truss. The jackleg I referred to ordered trusses from a truss plant, there was no comparison in price or timing. He cost them time and money because he couldn't hand frame a roof.

Anyway...

This is how to cut a rafter set as described using Rich's calculator that was asked about in the original post.

Picture 1 shows a framing square aligned on a piece of 2x6 stock. The 12" mark is highlighted on the body (right side) of the square, the 7" mark is highlighted on the tongue (left side). I've used a set of square nuts to hold the square in alignment for repeatability, handy but not necessary. Since the square is a 90 degree angle all plumb (vertical) cuts can be marked on the tongue. The complimentary angle, level or horizontal cuts, can be marked from the body of the square.

Picture 2 shows a speed square aligned on that top plumb cut. This will be the top end of the rafter against the ridge. Notice that it reads a 7/12 pitch and that is a ~30 degree angle. Remembering high school math 90-30=60. The seat cut is going to be about a 60 degree angle. So our framing square is marking 30's off the tongue and 60's off the body at this pitch.

For picture 3 I hooked my tape on the long point of the top cut and pulled it along the top edge making a mark at 68-5/8", the rafter length computed in the calc.

Picture 4 shows a plumb mark drawn along the tongue of the square on the 68-5/8" mark. I then slid the square over and used the body to mark a 3-1/2" long level seat cut. This is the birdsmouth.

For picture 5 I slid the square over till the body registered on a whole number on the body. I wanted a 6" overhanging tail and made a mark on the level 6" from the birdsmouth plumb line.

Picture 6 shows the plumb cut scribed on that mark.

[Don_P]

Whoops hit the pic limit, pic 6 is on this post.

Unless the ridge is structural you still need to use ceiling joists to keep the rafters from pushing the walls outward.

[woodall83]

Don,

You didn't, no worries. My post was in response to this.

Why would you need trusses to span ten or twelve feet?? That makes no sense.

[newby]

It was not my intent to offend you Woodall. You are correct in that trusses can be used, and yes site built trusses would compare very well. Feel free to show how to build this as a truss. The jackleg I referred to ordered trusses from a truss plant, there was no comparison in price or timing. He cost them time and money because he couldn't hand frame a roof.

Anyway...

This is how to cut a rafter set as described using Rich's calculator that was asked about in the original post.

Picture 1 shows a framing square aligned on a piece of 2x6 stock. The 12" mark is highlighted on the body (right side) of the square, the 7" mark is highlighted on the tongue (left side). I've used a set of square nuts to hold the square in alignment for repeatability, handy but not necessary. Since the square is a 90 degree angle all plumb (vertical) cuts can be marked on the tongue. The complimentary angle, level or horizontal cuts, can be marked from the body of the square.

Picture 2 shows a speed square aligned on that top plumb cut. This will be the top end of the rafter against the ridge. Notice that it reads a 7/12 pitch and that is a ~30 degree angle. Remembering high school math 90-30=60. The seat cut is going to be about a 60 degree angle. So our framing square is marking 30's off the tongue and 60's off the body at this pitch.

For picture 3 I hooked my tape on the long point of the top cut and pulled it along the top edge making a mark at 68-5/8", the rafter length computed in the calc.

Picture 4 shows a plumb mark drawn along the tongue of the square on the 68-5/8" mark. I then slid the square over and used the body to mark a 3-1/2" long level seat cut. This is the birdsmouth.

For picture 5 I slid the square over till the body registered on a whole number on the body. I wanted a 6" overhanging tail and made a mark on the level 6" from the birdsmouth plumb line.

Picture 6 shows the plumb cut scribed on that mark.


Don, Great picture instruction This is just the info that i needed. Thank you!!:D

[Richard A Hetzel]

Snide remarks aside, with a rafter span of 5 feet, 2x4 rafters are adequate, so why go to the trouble of trusses? As I said, it makes no sense, but now I'll say it makes ABSOLUTELY no sense.

[Don_P]

R802.6 and R802.7.1 would preclude the use of 2x4 rafters for most situations. worth studying before going that route.
R802.10 can give some inspectors heartburn on site built trusses. My nephew just used some on a habitat build last week though.

[Richard A Hetzel]

I don't know what code you're looking at, but mine gives a full range of values for 2x4 rafters, 30 psf ground snow load, 16, 19.2 and 24 inch spacing, and all of them are greater that 5 feet, except for 3 which are exactly 5 feet.

[Don_P]

Same as yours, same edition. Span rating is just one concern. Read the cites... why does that make it mighty hard to pull off?

[mjpliv]

As the risk of pissing off a whole bunch of people, is there a reason to cite building codes and span tables for a 10x12 shed? Unless your area requires a plan review and/or inspection for a utility shed to keep your lawnmower dry then I think common sense should prevail. If the codes or span tables do not apply to this type of structure then just about anything goes. The rafters span only 5 feet so it is inconceivable that a 2x4 would not be sufficient to carry the roof. Hell! I would be shopping for 2x3's!!!!

Installing the collar ties at 30% rafter height effectively increases the performance even more. (You are installing collar ties aren't you? The wall is 12 feet long and should be restrained against out-push. Even for a shed!)

[newby]

Listen guys, I really appreciate the help. all i needed was the how to and Don gave me all i needed to know the rest i will decide for myself(2x4, 2x6 Etc). And for those of you saying trusses aren't necessary. I am sure your right. As i stated in my first post I am not familiar with the proper terminology so yes rafters would be fine. The shed I am building doesn't have to be anything special. It will probably turn out to be one of those sheds that you guys would walk into and go what dip sh#t built this. But I am doing as much research as i can to do things the proper way and have only gotten floor completed which i feel turned out great. when the weather gets nice again i will finish the walls and then roof and I will post some pictures to get your feedback. Thanks again for the help. I probably will never confuse trusses and rafters again.

[Don_P]

Newby,
Please accept my apologies for the behavior you've had to witness. I had hoped to post a tutorial that I could refer others back to for simple rafter cutting. I tried to show methods that would work for not only a shed but that you could use confidently on a house.

I have been trying to politely offer information on construction and help foster a place where reasonable people feel they can talk about these things without running into the typical "who's stick is bigger" confrontations. As you can see we're dealing with humans and egos so its definitely a work in progress.

Don't let this drag you down or make you feel any of this was in any way your doing, it wasn't. I am going to close this thread to prevent any more foolishness but that doesn't mean I don't want to hear from you. Please start another thread for any more questions and yup, we want to see your pictures :)