I have a renovation project on an old row house ( circa 1925). The front part of the house is 14’9″ wide by about 26′ deep, with two common solid brick walls. The rear room ( kitchen) narrows to 12′ wide by 14’deep, and has only one common wall. We have removed the plaster and lathe, and the wall partitions running the width of the house. The floor joists and rafters run across the house , are on 16″ centres and are rough sawn with dimensions of 2 3/4″ by 7 3/4 ” ( i.e. 2×8).
Tables in both a carpentry manual, as well as an architectural manual state that a 2×8 on 16″ centres can span 14′ with a 40 pound live load. The second floor joists in the kitchen are therefore sufficient.
A narrow staircase runs up on one side, starting about 14′ from the front door. There is a wall partition about 11′ feet long, making an entrance hallway about 2’6′ wide, and it of course runs front to back, with the second floor joists crossing it perpendicularly.
There are double joists running across the house where the house narrows at the start of the kitchen, as well as where the opening for the stairwell is on the second floor, and double joists running front to back between the two double joits running across the house.
We want to open up as much of the house as possible on the main floor to have one large living / dining/ eating area. I do not know if the 11′ feet of wall running from the front door down the hall is load bearing or not.
The question ( after the long winded description ) is can this wall be removed if we double up on the 2×8 second floor joists without having the doubled up joists tie into the walls? That is, can we simply ‘pony’ an extra board to each of the floor joists to provide it with additional support in the centre of the span, even though the ‘ponied board is not supported by the walls?
It seems to me that this would provide floor rigidity, considering that with a 30 lb live load, the span could be 17′.
Any advice would be greatly appreciated.
David.
Replies
can you post a drawing of all that?
or a photo or two?
I got lost in the detail
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Hi Piffin,
I will take some pictures tomorrow and post them. I agree that the detail is a bit much.
David.
A quick simple would help too. Attached is an example of what it might look like.
Seems like you could get at least one end of the new, sistered, joists to sit on the load bearing wall... Unless the joist end bays have been bricked in or something.
Regarding the 11' wall that you are not sure if it is load bearing or not, what is under it - ie, in the basement? Assuming a basement (or crawl space).
Edited 7/11/2008 6:19 pm ET by Matt
Thanks Matt,
There is a basement, and it does not have a wall down the side so the main floor joists must be spanning the distance.
David.
I'm surprised no one has said this yet, so I'll be the first: you need an engineer to look at this. Where I live, our LVL beam supplier has an engineer on staff who takes about 10 minutes to figure these kind of simple, straightforward problems out.
I seriously doubt you could do this with sawn 2x8's. (By the way, what species are they? SYP?) They sound like they are already close to their max. Headering off a bunch of joists and then hanging the header from a couple of 2x8's which are already stretched to their limit...I doubt it.
It sounded to me like you want to sister the joists at the point where the wall used to be? Like making a joist sandwich? Don't do that. Marson is right. Call a lumber yard and get the LVL dealers engineer. This would be a piece of cake for him/her to figure out while actually looking at it.