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Old 10-10-2013, 07:26 PM   #1
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how much bearing ?


i am going to sister some 2x8's floor joists under my new kitchen. for cabinet, counter top, and people weight, that is going to be in there soon.
11'3" span, block foundation with rim joists on both ends. no blocking yet.
i wouldn't be able to get full length boards in there. but i am thinking that if i could get 2" on each end, i would be good. watcha think ?

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Old 10-10-2013, 08:44 PM   #2
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but i am thinking that if i could get 2" on each end, i would be good.
not sure I'm following ....

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Old 10-10-2013, 08:58 PM   #3
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how much bearing ?


2" of bearing is fine. Minimum is 1 1/2" for a joist, where I live.
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Old 10-10-2013, 09:16 PM   #4
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2" of bearing is fine. Minimum is 1 1/2" for a joist, where I live.
that is exactly what i was thinking. after all, to do what i want, i don't think i need to be on the blocks at all. but it would be better and make me feel better.
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Old 10-10-2013, 09:22 PM   #5
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not sure I'm following ....
2 blocks walls/foundation. 12' outside of block. rim joist on each, floor joists connecting. 11'3" inside span of block walls. i could not get 12' boards up in there. so if i cut the new joists to 11'7", i think i could get them in. then sister them.
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Old 10-11-2013, 12:59 AM   #6
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Really you don't need any bearing. I would just cut the sisters about 6" short to each end (about 10' 6" - 11') and nail 16 d s in a staggered pattern 8" O.C.
That will stiffen the existing joists up nicely I think.

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Old 10-11-2013, 02:22 AM   #7
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Originally Posted by Fix'n it View Post
i am going to sister some 2x8's floor joists under my new kitchen. for cabinet, counter top, and people weight, that is going to be in there soon.
11'3" span, block foundation with rim joists on both ends. no blocking yet.
i wouldn't be able to get full length boards in there. but i am thinking that if i could get 2" on each end, i would be good. watcha think ?
I am not following you on this. Your span is no different than how my house is set up. Do you plan on doing a lot of entertaining after the Kitchen remodel, that you will have a lot of people, with one person per every two square feet?

Really if your current structure is sound, I really see no need in beefing up the floor joists, unless you are finding a lot of rotted out members, or members that are sacrificed, due to cuts into them, that have caused them to no longer be able to support much load; then yes you should look into sistering another member next to each one, and fix any damaged sill plates, along with supporting member across the middle of the house in the basement.
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Old 10-11-2013, 09:09 AM   #8
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how much bearing ?


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Originally Posted by AndyGump View Post
Really you don't need any bearing. I would just cut the sisters about 6" short to each end (about 10' 6" - 11') and nail 16 d s in a staggered pattern 8" O.C.
That will stiffen the existing joists up nicely I think.

Andy.
Indeed. Full-length sistering does two things: it increases the floor's strength and its stiffness. Short-length sistering increases only stiffness. This is an important distinction. So, if your floor's joist span supports standard room loads (40 psf live load, 10psf dead load), and you're not exceeding that by, say, hosting parties with people packed in like sardines, or putting extraordinarily heavy furniture in the room, then there is no need to increase the floor's strength. In that case, you need not worry about bearing the sister joists. If you can, great. If you can't, no problem. I'd simply recommend increasing the nailing schedule a bit near the joist ends in the latter case.
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Old 10-11-2013, 09:10 AM   #9
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I am not following you on this. Your span is no different than how my house is set up. Do you plan on doing a lot of entertaining after the Kitchen remodel, that you will have a lot of people, with one person per every two square feet?
When I received the final blueprints for my log house, I noticed that the floor joists were doubled in several places (and they are 2x10s). Also, in the kitchen area, they were spaced at 12" oc. When I called the company to ask why, the answer was "we don't like squeaky floors so we overengineer them in the high traffic areas." Believe me, they overengineered everything. My rafters are 2x12s. It was quite a treat for me and the wife to put those things up.
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Old 10-11-2013, 01:33 PM   #10
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When I received the final blueprints for my log house, I noticed that the floor joists were doubled in several places (and they are 2x10s). Also, in the kitchen area, they were spaced at 12" oc. When I called the company to ask why, the answer was "we don't like squeaky floors so we overengineer them in the high traffic areas." Believe me, they overengineered everything. My rafters are 2x12s. It was quite a treat for me and the wife to put those things up.
Usually over Load bearing walls, they will double the joists at those points. I have that in my house. One set of joists under where the entrance to our bedroom is, and one where the wall is between the dining & kitchen.

And yes, no one wants squeaky floors, especially if you are placing tile down. 16" o/c is fine at the min., and really should be no less than 2x10 joists, 2x12 would be better. Especially if you are tiling.

2x8" could be what the code min. was at that time where the OP lives. A lot of Sears & Roebucks built up in Chicago Land. Even my town, there are a lot of Vrendeburgh Lumber co. homes, along with Sears, and one other company that built nothing but Tract developments, but they built them to last back then.

I do not think that the OP has anything to worry, with their current setup, unless they plan on placing 150 or so people on the floor at any given time. The cabinets and flooring material is not going to change much, from how much weight has been on those joists up to now.
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Old 10-12-2013, 07:28 AM   #11
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there could be a lot of people in that room at one time. the floor is a bit bouncy. if i really tried, i could make it move much more than i am comfortable with. it needs reinforcement.

i could put posts, but i want to leave the space open.
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Old 10-12-2013, 10:27 AM   #12
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there could be a lot of people in that room at one time. the floor is a bit bouncy. if i really tried, i could make it move much more than i am comfortable with. it needs reinforcement.

i could put posts, but i want to leave the space open.
Have you posted before a picture of what the flooring structure looks like from below? Also what are the spans between Lolly columns or Brick Support columns. What is supporting the load through the middle of the structure, that the Floor Joists are resting on?

If they are 16" o/c, placing another 2x8 on each joist, would bring it to around 14" o/c. The biggest problem is that you will have to pull all plumbing, electrical that goes through the existing beams that are down there already.

Your span is around the same as mine, but when they built our Bungalow, they used 2x10's. Some of the Catalog homes, 2x8 was the bare min., depending on the year that they were being sold.

Our home was built in 1937, and the finished flooring is only 1/2" thick. That is about the only thing that I do not like about this place. Other then that it is solid.
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Old 10-12-2013, 09:21 PM   #13
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how much bearing ?


conventional lumber joists only require 1 1/2" bearing, if your using engineered joists you need 1 3/4
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Old 10-13-2013, 08:56 AM   #14
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Have you posted before a picture of what the flooring structure looks like from below? Also what are the spans between Lolly columns or Brick Support columns. What is supporting the load through the middle of the structure, that the Floor Joists are resting on?

If they are 16" o/c, placing another 2x8 on each joist, would bring it to around 14" o/c. The biggest problem is that you will have to pull all plumbing, electrical that goes through the existing beams that are down there already.
no pic. like i said. its 2x8's spanning 11'3" (inside. 12' rim joists). block foundation. thats it.

plumbing is not much in the way. i may have to pull 3 romex, idk yet.
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Old 10-13-2013, 09:58 AM   #15
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Fix'n It,

I would follow OCD's and Andy advise and sister another 2x8. This is YOUR house. I tore out a kitchen and added sister joist to every joist in the floor. I then laid 3/4 + 1/2 grade A exterior ply down. The tile contractor was thrilled the floor was so solid. Over engineered, YES. Do I care, NO!

After 3 years NO grout cracks or broken tile. Many parties with many people in the kitchen.

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