Hi everyone. For those who thought this was a how-to, my apologies.
I want to remove most of a load bearing wall diving my kitchen and dining room. I'd like to drop the wall to a half wall (about 40" high) and install a bar counter top on it. This will open things up in the house quite a bit. Here's the wall I want to chop:
Figure 1: From the dining room side
(I want to remove from the doorway over to the right to the back side of the fire place where the brick is)
The section I want to take out is about 9ft long. This wall is indeed load bearing. Here's what it looks like from the attic (all pics are taken from the dining room side):
Figure 2: General shot showing the joists and supports
Figure 3: The wall runs right where the joists overlap and join together
Now, I have searched to see if it's possible to do a beam across resting on the tops of the joists like the two beams already up there (Figure 2) but I found very little info and the info I did find pointed to a flush beam instead, requiring I cut the joists (big suck). Since I did not find any info on a beam above the joists, I'm assuming there's a reason why. But there are already two beams like that up there and I won't be taking the entire wall out.
What is a good way to proceed?
Side question: when the wall is dropped to 40" high, how can I prevent the end of the half-wall (where the doorway is) from wobbling and being pretty unstable? My idea was to have the end of the wall make a right turn into the kitchen and stick into the kitchen about 12-14" as a brace for that end of the wall. There will be cabinets on the kitchen side of the half-wall so it shouldn't look too funny.
Obviously, you will need to install a header that supports the weight. The dimension for that header depends on the span .... 9 feet. The traditional rule of thumb used to size headers is the "inch per foot" rule which will provide adequate strength in most cases with spans up to eight feet. For your situation, it looks like a doubled 2x10 with a 1/2" plywood center piece would carry your load ... AND I would expect to see verticals supporting the ends on both sides. You also want to nail off the celing joists to the new header to tie everything together. Overkill might involves metal Simpson Ties.
I will defer to anyone who wants 2x12's ... more is always better ... but you do not have a 2nd story sitting on this opening so the load is not massive.
You must erect a temporary wall to hold the ceiling while you remove the existing wall and install the new header. You could go with a glue-lam but I am not sure about the sizing.
This decision is an engineering choice based on loads and span. Any good lumber yard (not HD) can help you make this call. This is not a difficult job, just one that requires good pre-thinking and some help (a doubled, 9 foot, 2x10 is heavy to lift into place)
I agree with most of what Villa has said. The two 2x6s in the attic are coller ties to hold the sides of the house from speading. Two 2x10 will do the job. The plywood between can cause more touble than it worth when the 2x stock shrinks. Like villa pointed out you will want 2 temp walls and leave the top plate in place and install two jack studs at each end. You can put the 2x10s up one at a time and nail them in and together 4 nails every 16". Down stairs you need solid blocking between the floor sheeting and wall below and 2 studs directly below the jack studs above. Add a 2x4 below the beam between the jack studs for drywall.