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Convert trusses to cathedral ceiling

Hans_Delius's picture

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I have a twenty year old ranch with job-built W trusses installed with a continuous 2x8 ridge. Top chords are 2x6, the remainder 2x4. I want open a section up and somehow rework the existing trusses to allow for a cathedral ceiling. The open space above the bearing walls is approximately 15 inches, so-called energy trusses in this area. Any suggestions other than tearing everything out and starting from scratch?

(post #167525, reply #2 of 11)

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Thanks, Tom.
My next step is to contact a truss engineer.

(post #167525, reply #6 of 11)

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Blue,
Thanks for the reply. To clarify the situation, the area in which I want to convert to a cathedral ceiling is under one end of the main roof, over the living room/dining room. The width of the house is 28’8” but the total span of the truss is 32’8” to the facias. The trusses are 2’ on center and the length of the 2x6 (Michigan Truss)top chords are 18’. Height at the center is 7’3”. The length of the section I wish to open is about 20’. There are no supporting interior walls in this portion of the house, and in the remainder of the house a hallway runs down the center. The supporting steel beam in the basement is off-center at one side of the hallway. This makes it difficult to support a heavy ridge on the interior end. The other thing that makes this interesting is that the only portion of the truss resting on the exterior walls is the bottom chord, which is what I want to cut out. One thought I had was to support the top chord over the exterior walls with cripples and then use 2x8 or 2x10 to form an X brace from the exterior walls to the opposite top chord and bolting that to the original truss members where they intersect. This would take over the horizontal stress of the bottom chord. I am not sure, however, how much lower the X-brace would have to be at the center to take the snowloads of northern WI. An engineer may still be my best bet.
Hans

(post #167525, reply #8 of 11)

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Thanks for all the help. I'm contacting an engineer next week. Hans

(post #167525, reply #10 of 11)

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I have a twenty year old ranch with job-built W trusses installed with a continuous 2x8 ridge. Top chords are 2x6, the remainder 2x4. I want open a section up and somehow rework the existing trusses to allow for a cathedral ceiling. The open space above the bearing walls is approximately 15 inches, so-called energy trusses in this area. Any suggestions other than tearing everything out and starting from scratch?

(post #167525, reply #1 of 11)

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Hans,

I think you will have a fairly easy and rewarding project here with at least two options that I can think of. I speak with direct experience in this subject because I did just this last year.

While framing a new house last year we realized after the roof was dried in that the homeowner envision a vaulted ceiling in an area that we had installed standard trusses. The prints were vague in this area. Several ideas were kicked around but this is what I came up with. I had the truss manufacturer design scissor trusses at the appropriate pitch in two pieces. This served two puposes. We were able to get them into the room this way and install them under the existing roof. We lifted the halves into place on top of the wall and sistered them to the existing trusses. The truss engineer spec'd a gusset design and nailing schedule for fastening the two halves together. Then we simply cut out the unwanted portion of the regular trusses. It took a three man crew about 8 hrs. to accomplish for a 24x32 room. Of course the design was reviewed and approved by an engineer.

Of course your situation will vary in that there are finished surfaces, mechanical, insulation and the like but the process would be the same if you can move these items cost effectively.

Other options are a load bearing ridge which doesn't seem practical or stick framing a traditional rafter and collar tie system. This could be accomplished in much the same manner, by sistering rafters and collars to the existing trusses. Again I would check with and engineer on this.

Good luck,

Tom

(post #167525, reply #3 of 11)

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Hans, how long is the span for those 2x6 roof members?

If it's not too long, it probably won't be too much trouble convertng them. The truss is designed to make that 2x4 work as a ceiling joist, but the 2x6 rafter is probably sufficient with just a few collar ties added. After all, isn't that what a "conventional" consists of?

I'd probably (depending on span) just whack the existing ceiling out, and install an interior 2x6 (possibly 2x4) interior, conventional ceiling. Care must be taken to maintain the outward forces applied by the new conventional system. That might require a few ties (these can be exposed) or a heavier ridgebeam, depending on the length.

Some consideration must be given, to the ceiling in the remainder of the house, if the truss that you cut, is spanning more than one room.

What the total size of the room that you want to open?

Blue




(post #167525, reply #4 of 11)

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Hans go with the engineer and get an opinion!

Regardless of your options, you still have to respect your local building codes. They were designed, (for the most part) to ensure a safe dwelling for you and your family.

(post #167525, reply #5 of 11)

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All alterations do not need engineering specs!

Here in MI, I would not encounter any resistance from the bldg inspectors, as long as the finished roof was similar, and spec'd the same as a conventionally framed system (ie: 2x6 rafters, 16"oc or 2x 10's 24" oc, etc.

If the roof in question is a 16'family room, projected out from the main roof, the answer would be as simple as removing the ceiling joist, and installing a dropped ridge beam.

The cost of the engineer would exceed the entire material list for the "fix"!

If the built on-site truss was elaborate (I doubt it, or it would have fallen down long ago) the engineer is a necessary evil.

Been there, done that in MI,

Blue




"Hard work has a future payoff. Laziness pays off NOW."

(post #167525, reply #7 of 11)

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If you were me, you'd be whacking and stacking already.

If I was you, I'd get a qualified opinion. The 32' span is not too big of an issue, but the lack of foundation needs to be dealt with. We add cripples all the time to or heels here. There are horizontal stresses that need to be considered, usually solid or x blocking will do the trick.

You probably won't need a bearing ridge. The Cathedral syle ceiling will actually strengthen the roof system, providing that a solid foundation can be obtained. If the midspan wall is not landing over the steel, you might have to think about reinforcing down below. If the steel beam is positoned under the wall (the one that seprates the living and dining), you are home free.

What is the dimension of the room that is going to have a cathedral dceiling in it? Or are you considering a cathedral that will span both rooms (the living and the dining?)

Blue



(post #167525, reply #9 of 11)

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Dear DSOB,

The point is not wether the visiting engineer liked your solution, the point is would he attach his seal to your solution.

I assume you had a building permit to do this structural change to the roof of the commercial building in question and that it was inspected and approved. Otherwise, you may still be liable for any damages that may occur in the future, if you violated codes.

Just a word to the wise,

Gabe

(post #167525, reply #11 of 11)

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Gabe

Point taken