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ChaosTheory
Joist repair options

Hi folks,
I recently purchased a 1890's 4-square to gut and rework. Currently, having replaced foundation and gutted, I am working on dealing with old framing issues and the local inspector.

To give a little understanding with the latter, the inspector is dealing primarily with new conventional construction in the 200-300k arena. He is not well versed in older framing systems especially not so much in terms of dealing with repairs of older framing systems.

The issues on the former are as follows:
The second floor joists (2x10) span 24ft fwd to aft being supported roughly in the middle, some of these joists do make the complete span and are spliced in a section which does not have any support wall.

Additionally, there are some odd mid-span "headers" as shown in the following 2 pictures.

What I need is some type of official documentation that would cover the repairs of older framing systems. I would rather no have to run a lot of additional sisters or doubler joists.

Thanks in advance.

A. Spruce
Re: Joist repair options

If you think your inspector is unqualified to be advising on your home, call the building department and request that someone with historical structure experience be the one to do your inspections.

Since you've stripped the place to bare studs, you can expect to bring most of the structure and it's appurtenances up to current code. That may or may not mean sistering or replacing joists that have not been spliced or supported correctly, as shown in pic 2.

ChaosTheory
Re: Joist repair options

One thing that I should have mentioned is that this is in small town America, so the entire area is covered by a single inspector. I do not think of him as unqualified, however, His view, I think, is that if you have something unconventional than you are expected to show that the design or application is sufficient and the burden of proof is on you (which I agree with).

I am not really concerned about the structural capacity as there is no bounce in the floor and that is before sticking in cross bracing (there is none existing) and fireblocking. Being a mechanical engineering student (the 20 year education tract), I went though each connection and span and found them exceeding the required capacity.

In Aviation we have manuals which cover just about everything including splices etc. My concern is that I have not found anything, like on old manual, which covers unconventional design/repairs. Surely there is some type of official publication that covers these type of things, right?

jkirk
Re: Joist repair options

i would build temporary walls to support the good sections of floor joists, then cut out the bad ones then install new joists. its tricky getting them up in place with the floor boards in place but it can be done as long as their is a interior bearing wall in place that you can slide the new joists through the cavity to work them back over to the exterior wall.

as for the header on the flat, thats no good unless its just an old rough opening which had some cripple studs installed and there is a proper header up above

ChaosTheory
Re: Joist repair options

I had thought of the R&R method, but would prefer to avoid if poss. I think that if I were forced into replacing it would be a better choice to simply run a joist adjacent to the existing. There is nothing supporting the joists other than the standard mid-span load wall which I need to rebuild anyhow. Further, as there is no cross bracing it really would be simple to install in that respect.
I would simple like to avoid buying a bunch of wood if its not required, that along with extra junk needed to get the first floor ceiling shimmed out.

jkirk
Re: Joist repair options

sistering along side joists that are spliced will actually use more lumber than simply replacing the bad sections. as you need to fill in where the splice doesnt continue then put your new full length joist in. along with this you will need a combination of construction adhesive screws and nails. not to mention the you wont get a perfectly flush joint between teh old and new do to filling in with newer lumber which isnt hte same thickiness

Sombreuil_mongrel
Re: Joist repair options

At minimum the joists that bear the headers must be doubled. There's no clever substitute. Unless you want a post under the header ends. As I said on another board where you posted, this framing would be failed by any inspector were it new construction.
Casey

ChaosTheory
Re: Joist repair options

Sorry about that, I sort of just dropped off the face of the earth for a bit.
I appreciate all the thoughts, especially enjoyed looking a little bit on "the devil queen" blog (although a little too close to home).
After spending some time looking into the suggestions and armed with an old engineering book from the 70's which specifically talks about this type of joist scenario I went down to visit the Inspector. Of course I had a rough sketch with me as well. Basically what it has boiled down to is the following pcs.
(a) its an old house with old wood which is well over-sized joists for the spans.
(b) there is no deflection with 1400 sf of 3/4" wood flooring sitting directly above the splices.
(c) there is not any real vibration when a 200lb beast jumps heavily above them.
(d) the nailing schedule on the splices is good-although I am adding a couple bolts on each for extra safety margin.
(e) I will be adding solid cross bracing in such a way as to ensure the splices can not twist or separate.
(f) these joists only support a bedroom floor
(g) I am not making any substantive changes to the location and loading of the bearing walls.
Given these considerations he was comfortable giving the green light for the specific installation.

For those of you who might be interested in finding more information about this type of joist solution try looking in:
'75 copy of "wood frame house construction" USDA, Forest Service, Ag Handbook #73 under the "in-line joist system"
Additionally you might be interested in researching the condition called "beam overhanging support"

What it functionally ends up being is a uniformly loaded cantilevered beam with a small point load at the end, with the exception of the size of point load it is not at all unlike a cantilever with a load-bearing wall which is commonly accepted today.

Thanks again for the input. It really does help to talk with your inspector without seemingly like a know-it-all or looking like an unprepared moron.

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