building rafters

since a truss cannot be built , what are the dimensions used to lay out/build a rafter? I'm trying to save a friend a little money.
I've done them before, but it's been several years.
Thank you.

 

Well, a truss can be built and they are everyday.

The "dimensions" on a rafter are gonna depend on the size of your building, the pitch of the roof and so on....there is no "magical" one size fits all formula. And also with rafters, if the width of the building is enough that you can't span the ceiling joist with one pc of lumber, you'll have to have a support beam and posts down the center.....which is often a distinct DISadvantage in a garage.

 

raiseframe,

Building a truss can be done but why would you?

One, if a building permit was pulled...hand frame will have to be done to meet code.

Second, building one by hand will require some hefty stock as those that are pre-engineered already have a structural approval stamp. The inspector will want to see something that assures it meets code...engineered drawings.

Third, by the time you acquire the means to do all this, the cost will not be cheap and you will eat up alot of time.

In summary, do you and your friend a favor....purchase pre-built trusses...cheap, approved and easy to put up...great time saver!

Good Luck!

 

Doug & TN Andy: For your information, here is the defination of a wooden truss: This comes from the Building Code Construction Book which is known as the builders bible.
"A truss consists of short, straight, ridgid menbers commercially assembled under very strict engineering conditions into a triangular pattern. This strict triangulation is what makes a truss a rigid structural unit. While a truss as a whole is subject to bending, the individual members are subject only to cpmpression and tension."

Raise Frame: Now if you will let me know what the span of the rafters will be, and the pitch of the roof, 4/12, 5/12/etc., I will be glad to give you the dimensions so you can build your rafters for your friend.

 

Jack the Contractor,

I said hand frame can be done as long as it meets code. Ridge, rafters, collar ties,etc.

 

Jack, et al,

I sorta came in late on this discussion of trusses and rafters having not read the first post on down the line where yall told him not to build his own trusses but to buy commercially made ones, thus I didn't quite "get" what the guy was saying when he started off with "since a truss cannot be built".......

When I said trusses Can be built and they are everyday, I DID mean commercially......because that's the way most of 'em are.....

That said, I HAVE built a lot of them on the job and they do just fine. One of the distinct advantages we have in my area is we don't have building inspectors in most counties in Tennessee....of course, that also works to a disadvantage sometimes when people do stupid or shoddy work, BUT it does allow you to do certain things without having to seek the permission of a government weenie that often doesn't know their backside from a hole in the ground.

The trusses on my own personal shop are an interesting gambrel type ( Dutch barn for those reading this that don't know roof styles) that has an "open" leg on the 45 degee down slope side with a conventional king post top on the upper shallow slope....it spans 35' and is made out of white pine 2x6s I sawed off my mill and property. I have NO doubt I could have never done this in a place that a weenie inspector would have to sign off on it, but it is stout, strong and does me quite well......

But also this week, I've been working on a house down the road that was built about 25 years ago and they obviously built the trusses on site using store bought SprucePineFir grade lumber and some undersized plywood plates for their gussets. The choice of lumber was poor.....commercial trusses in this part of the world use Southern Yellow Pine because it is MUCH stronger than SFP grade framing ......and the undersized gussets plate were hand nailed and they used way too few nails......the end result being the trusses sagged in places where there was open span from one outside wall to another......we had to go back in an built a header in the living-dining area to jack the roof back up.

When I build a truss, I generally oversize the lumber, use large plywood plates, glue them, and fill 'em full of 6p nails from an air nailer. The designs I use come from some old government pubs where they used to show ya how to do it since there were no commercial places around to call for a set.

Building anything requires a good knowledge of what you're attemping. I recognize that a forum like this is NOT gonna give the average Joe that education and as such, the best advice is to go with commercial trusses.....if nothing else, they are probably cheaper since they buy their lumber by the railcar load, and especially if you consider your time worth ANYTHING...but do recognize there are a whole lot of homemade trusses out there doing a fine job of what they were intended to do.......and also some crappy ones ...............of course, I've seen a lot of old crappy 2x4 rafters systems too

OK...soapbox mode off.....

andy

 

Not a problem guys. My point was to make sure this man does not try to make one for his friend. Buy commercial. I have made some also. I even have a gang nailer (somewhere). I appreciate your answers. Andy, if we come to Tenn so see my wifes inlaws or outlaws this winter maybe we can look you up and have a nice visit. Have a good day.

 

Yep, I think based on the questions submitted, this fellow ought not be building anything to do with a roof, since that is one of the more complicated and crucial parts of a building.

Jack, I'm near Jonesborough in East Tennessee , if you get out this way, drop by.

 

Andy: My wifes roots are in the Lebanon Tenn area. Sounds like we could make a plan to visit.