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Posted by on August 30, 2006, 9:20 pm
wrote:
>4ax.com:
>
>> I am making a homemade truss for an addition to an existing barn. I
>> have never been any good at math. The barn roof was built to be a
>> 4/12 pitch. The barn walls are 107 1/2 inches outside front to
>> outside rear. I measured the existing rafters, and they are 113 3/8
>> inches long from the highest part of the rafter (at the peak). I used
>> an angle tool (tool to set to the same angle and transfer it to a
>> board), and I cut the boards at the same angle. OK, I transferred the
>> angles to the boards and cut them the same. Then I loosely nailed a
>> piece of plywood across these 2 planks where the angles meet (at the
>> ridge). I left the lower ends (overhang) a little long to adjust the
>> height, so it's right. That's where I get puzzled. I want to be sure
>> the height is the same. How do I figure this out mathematically, or
>> am I better off just stretching a string across the existing roof at
>> the top of the walls, then measuring from the peak to the string, and
>> moving the string to the homemade truss, and make sure the height from
>> string to peak is the same, before I nail the horizontal board across
>> the truss.
>>
>> If this was an outside wall, it would be fairly simple to make a 2x4
>> from the top of the wall to the peak, and be sure its the same as the
>> existing roof. However, this truss is being placed from pole to pole,
>> in the middle of the barn.
>>
>> If I am not exactly clear, here is what I am doing.
>> I bought and moved an existing pole barn. To move it, I cut it in
>> half because it was too large to pull down the road in one piece. I
>> now have both halves. One half is in the ground, the other half is
>> still on the wagon frame that I used to move it. I am adding on to
>> the barn as I put it back together. But I am adding in the middle.
>> I dont plan to put the half still on the wagon into the ground until
>> the new portion in the middle is built. The reason for that is so I
>> can shift around the other half in their (oversized) post holes until
>> the steel roofing and siding sheets fit together properly.
>>
>> The reason I am telling all of this, is because I can not just run a
>> string from the roof of one half to the roof of the other. I wish it
>> was that easy......
>>
>> Yes, this has been a complicated ordeal, but it will work out in the
>> end......
>>
>> Thanks
>>
>> Mark
>>
>>
>
>
>I'm not trying to be a wise guy. If you cannot figure this out
>mathematically, how did you design the truss based on the xyz loads and
>streses which requires significantly more complex math? Aren't permits
>for such work required in your area. To get one issued, you would have
>had to submit a truss design with specs signed off my a PE, Certified
>Professional Engineer.
>
>The discussion on making your own trusses has been hashed over before
>here. Bottom line is it's not a good idea. The impact of truss failure.
>long or short term, can be fatal.
Permits, Engineers ??????? NOT
This is very rural farm country, not New York City. A permit is
needed for a new home, and all that amounts to is to fork over some
money and give a brief description of the house and the size.
Barns and sheds dont need any permits, you just notify the county so
they can raise our property taxes.
These are not the kind of trusses you buy at Home Depot. This is
actually stick built. Two 2x6 rafters with a 16 foot horizontal 2x6
nailed near the bottom and several small 2x4 uprights. These are
also TRUE 2x6's made at a nearby Amish sawmill. I'm just matching the
existing home made trusses, but I still got to get the angle right.
There wont be any truss failure the way I brace stuff.
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