Converting Roof Rafters Into Trusses

Hi All,
I want to remove a load-bearing wall that separates my living room from my kitchen. The attic is constructed of regular roof rafters and the span is roughly 25 feet. I'm exploring different methods of accomplishing this. The obvious method is to install a beam, but I also want to look into the prospect of converting the existing roof rafters into trusses. I've been unable to find much useful information online so far.
Can anybody recommend any resources (preferably online) that detail the pros, cons, risks, and methods for a do-it-yourselfer to do such a conversion? I don't know if I will do it this way or not, but I would like some reputable websites that would at least tell me whether or not I can.
Thanks to everyone for any information you can provide!
Ken
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I am no engineer, however, while it may be theoretically possible to convert rafters and ceiling joists into a truss, most roofs are not constructed in a way that would allow a conversion to a truss, most notable the connection between the rafter and the joist at the outside support walls plus any splices or joints in the ceiling joists that may not align or not have any torsional strength. Trusses are normally built unloaded, installed and the load added. It would be difficult to conceive how to build it in place while under load.
If you are just supporting a ceiling and not a second floor, it should be possible to add a modest size gluelam beam to support the ceiling joists. Getting it up and in the attic is the biggest challenge, but you may have the same problem getting wood up and installed to create trusses.

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snipped-for-privacy@iowatelecom.net wrote:

...
No "reputable site" will do such -- there are too many variables and unknowns given the potential problems to do such. That's why there are engineers and requirements for licensing of same...
As an example, there was an article in FHB a couple of issues ago where a contractor made some modifications -- I didn't read it terribly closely at the time as it wasn't of particular interest, but wondered about the soundness of a couple of things he did. The next issue contained a very detailed letter from an engineer who _did_ read it and pointed out many issues that were either inadequately addressed or totally overlooked in the modifications.
One of the interesting points was that the load calculations indicated the "by feel" new ridge beam was undersized such that the load is roughly 4X design values for the size chosen...
--
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snipped-for-privacy@iowatelecom.net wrote:

I have done this on several occasions where the original construction of the roof had failed, or was inadequate to begin with. I did this under the supervision of an engineer. He designed and inspected the installation of plate gussets and braces to create what became a truss. I have over 30 years of experience in construction and I would never do this without an engineer. This is just one of those times where you really need one.
You could however, install a beam in the attic to carry whatever needs to be carried by the removal of the bearing wall. Even this would be a good reason to contact an engineer for sizing, but if the situation is simple enough, you may be able to size and install a beam.
Good luck.
--
Robert Allison
Rimshot, Inc.
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snipped-for-privacy@iowatelecom.net wrote:

Trusses were built with plywood gussets before the metal plate method of construction was developed. Room permitting you could probably build trusses in place the old way with plywood.
Needless to say, getting drawings approved by an engineer and your local authorities will not be easy or cheap. Getting your butt into the available space to do the construction won't be much easier.
I helped a friend make his own trusses for a shed years ago. I later built a shed myself with trusses the same size. I bought my trusses. It just wasn't worth the time to build when I could buy them for almost the same cost as the material. The homemade trusses we made were in my opinion just as good as the ones I bought.
In reality you are still going to have a kitchen and a living room. A beam across the ceiling between the two rooms will not look out of place. With a beam between the two areas you won't have a battle trying to match the existing ceilings.
Keep it simple. The more you think about unconventional construction the more likely you are to outsmart yourself.
LdB
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