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Here are both the builder blue prints and foundation plans. According to the plans all external walls and garage are load bearing and internal walls are not. There is no built up foundation/headers internally, only thickened on external walls.

I want to completely take down the wall running horizontal from the garage to the kitchen which includes closet, kitchen wall, half walls (lv rm) and where pantry (no longer there) are indicated. Since the trusses run perpendicular and the middle of the truss (middle of the A) is where the wall is, my S/O is arguing it is load bearing. Full disclosure: I removed a quarter of that wall (next to the closet) more than 10 years ago based on these plans—no sagging to date.

Blueprint Foundation

closed as off-topic by ThreePhaseEel, Tester101 Dec 20 '16 at 12:17

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  • Hello, and welcome to Stack Exchange. It's best to include any diagrams in your actual question, but those images are too detailed to be useful here. – Daniel Griscom Dec 19 '16 at 16:27
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    What evidence do you have that the builders followed the plans exactly, using the correct trusses where indicated, and didn't skimp and use either less sturdy trusses or shorter trusses, turning some walls into load bearing walls in order to save money, stay on schedule, etc? Without explicit confirmation that not only are the plans well engineered, but they were followed, then this question can't be safely answered by an internet Q&A site. – Adam Davis Dec 19 '16 at 20:42
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    LV RM ? Living room – spicetraders Dec 19 '16 at 21:39
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    The rule of thumb I was given was that the limit for a wooden joist was 14 feet. If I understand correctly, you want to have 18+ feet unsupported. You might have gotten away with removing a little bit but I wouldn't push it. Time to get a structural engineer. – JimmyJames Dec 19 '16 at 22:40
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    I'm voting to close this question as off-topic because this situation needs on-site professional structural engineering advice. – ThreePhaseEel Dec 19 '16 at 23:54
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You really want to hire an expert. A house is probably the most expensive thing you will ever own; don't risk it if there is any doubt.

Usually, walls which run perpendicular to floor joists are assumed to be load bearing until proven otherwise. That doesn't mean walls along floor joists are not load bearing, but it's much less likely.

In older houses, walls may be carrying structural load even when they were not originally intended to, due to subsidence or past modifications.

Note that even load bearing walls can be opened up, by putting in a beam to take up the load and columns to transfer that load to adequate supporting points. Did that in my place, opening a 10-foot-wide passageway. But that really calls for an engineer to determine what will have to replace the wall, and involves building a temporary wall alongside it to take the weight during this process.... In my case the final result needed a double Paralam beam across the opening (equivalent to a hardwood 12x4 beam?), similar manufactured-lumber columns from that down to foundation and joist, and we had to sister that joist with a steel C-beam in the basement to help transfer load to the foundation and main beam. Definitely not something to attempt without expert on-site advice.

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My own house has double Fink trusses for most of the roof and in reading about the forces in trusses it is clear that the bottom chords of the trusses (serving as ceiling joists) are supported by the webbing and not from below by perpendicular interior partitions. In fact the bottom chords should be attached to partitions with slip fittings to allow the joists to rise above the partitions when temperature and moisture differences cause the trusses to deform slightly.

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However, the perpendicular partitions may provide lateral stability and you should get a professional opinion on the effect of the removal of this partition. Maybe a perpendicular 2 x 4 or 6 on the top of the ceiling joists would supply this, but without limiting "breathing" of the trusses. But see http://seblog.strongtie.com/2015/10/accommodating-truss-movement-besides-vertical-deflection/.

There is also the question of what removing this partition would do to the ability of the trusses to resist certain live loading conditions like a windstorm or roofers piling loads of shingles or sheathing.

Editing Putting 2 x lumber above the lower cords of the trusses is probably a nutty idea. In a redo near me of a 45-year-old house with trusses similar to mine, walls were removed to make a large open space similar to what you want and engineered beams put in. These project down maybe 10" from the lower chords of the trusses and are supported by posts.

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    Or snow. Snow is a hell of a load if you live in northern climates -- and generally stays put a lot longer than a windstorm or loads of shingles! – Doktor J Dec 19 '16 at 20:59

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